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ZOOLOGY LIBRARY
UNIVERSITY OF TORONTO

-

LIFE IN PONDS AND STREAMS

OUT-DOOR WORLD LIBRARY. —

THE OUT-DOOR WORLD; or, The Young

Collector’s Handbook. By W. FURNEAUX, F.R.G.S. With
18 Plates, 16 of which are coloured, and 549 Illustrations
in the Text. Crown 8vo. 7s. 6d.

BUTTERFLIES AND MOTHS (Bririsn).

By W. FURNEAUX, F.R.G.S. With 12 coloured Plates and
241 Illustrations in the Text. Crown 8vo. 12s. 6d.

BRITISH BIRDS. By W.H.Hupson,C.M.Z.8.

With a Chapter on Structure and Olassification by FRANK
EK. BEDDARD, F.R.S. With 16 Plates, 8 of which are
coloured, and over 100 Illustrations in the Text. Crown
8vo. 12s. 6d.

LONGMANS, GREEN, & CO.

London, New York, and Bombay.

" Digitized by the Internet Archive
in 2010 with funding from
University of Toronto

http://www.archive.org/details/lifeinpondsstreOOfurn

'YILJOULOLYD 39 "JON "po “jap ‘UopuoT “0D GB uosszaUvT

LALVTd

“WN

ee et Et

IN

PONDS AND STREAMS

S BY

\W. ee F.R.G.S.
AUTHOR OF

‘THE OUT-DOOR WORLD’ ‘BRITISH BUTTERFLIES AND MOTHS’ ETC.

WITH EIGHT COLOURED PLATES

AND NUMEROUS ILLUSTRATIONS IN THE TEXT

906192
6.4.40

‘LONGMANS, GREEN, AND CO.
LONDON, NEW YORK, AND BOMBAY

1896

All rights reserved

PREFACE

To a lover of Nature, all forms of life are interesting. But
so numerous and varied are those forms that few students are
able to give much time to the pursuit of more than one or two
branches of Natural History. It is not to be wondered at,
therefore, that most young naturalists devote their energies
to the study of the more conspicuous and attractive creatures
of Earth. Thus it comes to pass that a certain few of the
orders of Insects have quite an army of entliusiastic students,
that the beautifully marked and exquisitely formed shells of
our marine Molluscs are eagerly sought after, and that our
feathered friends and their eggs are well known and prized by
many lovers of wild country life ; while the study of the varied
living forms inhabiting ponds and streams, most of which are
not to be obtained without more or less careful searching for
them in their haunts, has but comparatively few devotees.

But there is no reason whatever why the study of fresh-
water life should not be quite as fascinating and instructive
to even the youngest naturalist as that of the more popular
branches we have specified above, and the chief reason why
the weedy pond and the winding stream are so generally
neglected is probably that our young naturalists have not
had their attention sufticiently directed to the world of
interest that awaits them if they will pursue their investiga-
tions of aquatic life with the same ardour that the collecting
of butterflies or birds’ eggs generally excites.

Let my readers, net in hand, ramble to the neighbouring

vi PREFACE

ponds and streams, fo:lowing the simple instructions given in
these pages, and they will find that everywhere the water
teems with life, and yields such a charming variety of forms
as can hardly be found elsewhere within such a small space.

It is with the object of directing young observers of
nature to these productive fields of labour that so much
space has been devoted to the practical side of the work; and
if those who are led to take up this interesting branch of
natural history will carefully follow the instructions given
for work in the field, for the management and rearing of
creatures in the aquarium at home, and for the preservation
of interesting specimens to be examined at times when out-
door study cannot be pursued, they will find themselves
amply rewarded.

The abundance of illustrations will, it is believed, greatly
assist the pleasant labours of the worker in this department
of animal life; and, to add to the interest of the subject,
much space has been devoted to an account of the habits
and life-histories of the creatures described.

But simply to read about the denizens of the water is not
to know them, and therefore the young student has been
encouraged throughout to make his own independent obser-
vations.

It must be admitted that the study of pond life is very
comprehensive, since nearly all the great divisions of the
animal world have freshwater representatives, and the number
of species is so great that it would be quite impossible to
include more than a small proportion in a volume of the
present dimensions; but a very careful selection of typical
species has been made, and every member of certain small
groups (e.g. the Amphibians) has been described as their
importance or commonness seemed to justify such a course.

Witel:

LIST OF ILLUSTRATIONS xi

FIG. PAGE

10. THe LrEEcu ' ; : : , ‘ ‘ ; 7

11. Nervous System or AN Rarienticons (BEETLE), SHOWING THE
CuHaIn oF GANGLIA, THE DOUBLE NERVE CorD, AND THE

SMALLER NERVES : ; ‘ : : , : ear 8
12. Cyciops, wirH irs Eco Sacs—MAaGNIFIED z : F ; 8
13. CHEESE MirE—MAGNIFIED . ‘ oe aes F ; —-. )
14 CentTiIreDE (Lithobius) . : : : : , : ; 2
15. THE THREE STaGeEs OF AN InsEcT (THE Buack Water BEETLE,
Hydrophilus piceus) : < : : P ; he
16. A Water Bue (Corixa Geoffroyt)—Twick NATURAL SIZE ay a 2!
17. Scorpton Fry : : ; ; : ; : , oe We
18. Cappis Fry (Phryganea minor)—TwIicE NATURAL SIZE. ae
19. THe Drone Fry (Eristalis tenax), onE oF THE Diptera—
SLIGHTLY ENLARGED . ; s 3 F ; TLS
20. A Mory wiry aquatic Larva aad aabia stagnalis) . me
21. AN aquatic BrrrLte (Agabus biguttatus)—THREE TIMES
NATURAL SIZE . he ‘ ; : : : aie 13
22. A HymMENopTEROUS INsEcT (Saw Fry) ~ENLanGep . ‘ ees
23. Net ror INSECTS ON THE WING . ; ; : ; SU: ae
24. Poxp Net ; : : : : . : ; » a7
25. THe Scoop or ScRAPER ; : : : : . es
26. THe Triancutar DREDGE ° ; F : , ‘ ee |
27. THe Ostonc DREDGE 2 ; : : , ; Or See
28. Tur Drepeinc Hook : - , ; ; : ~.
29. Wire Support FOR THE AQUARIUM ie : e ; Se en
30. METHOD OF USING THE DippING TUBE . ‘ ; d . 28
31. Dipprnc BorrLe anp Curie . ; : é SE
32. Tue ‘CoppineTon’ LENs : ; é 3 ; . os eae
33. THE STRAINER . : - : . ‘ ; : eee
34. A SrmpLe Microscope ; é ? ; : . . 36
35. A CHEAP FORM OF COMPOUND Sanendcons ‘ : ; w ., Joe
36. THe Srupent’s Microscope. ; ; j ; : . 88
37. SEcTION oF THE Spot LENS : . : : Jeng) (Oe
38. CeLL on Guass SLIP ; : : ; : . Soe
39. SHOWING HOW TO SOFTEN GLASS Tur BING : - ; Pag Cen
40. SHOWING WHERE TO CUT THE TUBE IN ORDER TO GET TWO
Dierinc TUBES WITH DIFFERENT APERTURES : ; . 41
41. Lamp witH SHADE 3 : ; : : , : iP re 44
42. A wipE SpeEcIMEN JAR : ; ; : . y ov 8
43. A Narrow SpecIMEN Jan. “ ; . ; . of ag Tae
44. THe Cyantpe Borrie . ; : : ; : , . 64

45. Tue Lauret Box ; : : : F : aS 55

xil LIST OF ILLUSTRATIONS

FIG PAGE
46. Secrion or a Serrrnac Boarp z : . : : ieee
47. SECTIONS OF THREE SETTING Boarps. : . F yin oo
48. A BurrerFLy on THE Serrinc Boarp . : F : > Se
49. A Dragon Fry on THE Setrinc Boarp . ; : oe
50. A BrETLE PINNED AND SET WITH WINGS CLOSED . : . #2
51. A smMaLL BEETLE MOUNTED oN CaRD—ENLARGED * ie
52. SprinG CLIP FOR HOLDING SMALL Brvatve SHELLS . f . 3ee
53. A SpECIMEN TUBE MOUNTED ON A Carp. Z , oo See
54. A Srore Box ror Dry Specimens. : : ‘ : . 69
55. THe Recrancuuar TANK . ; , : 2 ‘ vse Ceuee
56. Frnuine THE AQUARIUM BY MEANS OF A SIPHON. : ae
57. Heatinc WaTER IN A TEST TUBE. f ; : fo ee
58. ARRANGEMENT FOR A Founratn IN THE AQUARIUM . # . 80
59. ANOTHER ARRANGEMENT OF THE FountTAIN PIPE : es eek
60. ANorHER Metuop or AERATING THE WATER oF AN AQuaRIuM 82
61. Lemna trisulca : , . : ; ‘ | em
62. THe AMERICAN PoNnpWEED eaaedre avemts wm) . 5 | aio
63. THe Hornworr (Ceratophyllum demersum) . : ; . 88
64. Vallisneria spiralis . : ‘ ‘ : ‘ ee,
65. Ranunculus aquatilis . ‘ : , : : : ». 78
66. Potamogeton natans . : : : ; : : : ec ee
67. Potamogeton densus : : 4 : ‘ i ae
68. Potamogeton perfoliatus . : , E ; ‘ sat >
69. Potamogeton crispus : : : . 3230
70. Tue Lone-LEAVED PonpwEED GPuaengciani euites iis. 10
71. THe Varrep-LEAvep PonpweeEp (Potamogeton heterophyllus). 91
72. Tue Surntinc PonpweEp (Potamogeton lucens) . : > oY pee
73. THe Frar-srarkep PonpweEp (Potamogeton compressus) teh

74. THe FEnNNeL-LeaveD Ponpweep (Potamogeton pectinatus). . 91
75. Tne Spear-LEAveD Ponpweep.(Potamogeton lanceolatus) . 91

76. THe Grassy PonpweEp (Potamogeton gramineus) . >,
77. Tue Water Srarworr (Callitriche verna) . : ‘ :., ae
78. Toe Yernow Warer Liry (Nuphar lutea) sie OB
79. Toe Wutre Warer Linry (Nymphea alba) . i ‘ ee 2
80. THe Sweer Frac (Acorus calamus) . ; ; . - . 92
81. THe FLlowrrine Rusu (Butomus wmbellatus) ; ‘ Re
52. THe Greater Warer Pranrarn (Alisma plantago) . <5.)
83. Tue Lesser Warer Pranvarn (Alisma ranunculoides) . ws
84. THe Ama@ba—Hicuiy MaGniriep ; : : < to. OD
85. THe Ame@ba FEEDING, THREE STAGES ILLUSTRATED : * Od
86. Amaba pIvIDING ; F ; ; : ; 5:4) ee

87. Tue Super AnimatcuLe (Paramecium)—Hicuuy macniriep ~ 103

CONTENTS

PART I
THE COLLECTOR'S WORK
CHAP, PAGE
I. INTRODUCTION . ‘ ; ¢ , : . 1
Il. ON COLLECTING IN PONDS AND STREAMS : : bee

Ill. THE COLLECTING OF MINUTE FORMS OF LIFE. THE USE OF

THE MICROSCOPE : : : : : . od

IV. THE POND-HUNTER’S MUSEUM— PRESERVATION OF NATURAL
OBJECTS . : ; : . ; 48
Vv. AQUARIA AND THEIR MANAGEMENT : P : : 71

PART II
LIFE IN PONDS AND STREAMS

VI. LOWER FORMS OF POND LIFE : : : Si 99
VII. WORMS, LEECHES, AND THEIR ALLIES . : ae oe
VI. FRESHWATER MOLLUSCS : é ‘ ; ; 124
IX. FRESHWATER CRUSTACEANS AND SPIDERS : ‘ . LT
X. AQUATIC INSECTS : : ‘ ; > a
XI. FISHES FOR THE AQUARIUM , : ; . 846

XI]. AMPHIBIANS . : : : é , . . B60

LIST OF ILLUSTRATIONS

COLOURED PLATES
PLATE

I. THE AQUARIUM : : : : . Frontispiece

Il. FRESHWATER SHELLS . ; é - - Lo face p. 151

1. Spherium rivicola.

2. Unio tumidus.

3. Unio pictorum.

4. Anodonta anatina.

5. Dreissena polymorpha.
6. Paludina vivipara.

7. Planorbis corneus.

8. Limnea stagnalis.

Il. AQUATIC INSECTS . , i . : » 228

1. Notonecta glauca.

14. Notonecta glauca swimming on its back.
2. Nepa cinerea.

2. Nepa cinerea viewed from the side.

3. Dyticus marginalis. Male.

3A. Dyticus marginalis. Female.

3B. Dyticus marginalis. Male. Under side.
3c. Dyticus marginalis. Larva.

4. Acilius sulcatus. Male.

PCeaGOW FEIES . - . =< 2s 249

1. Platetrum depressum. Female.
2. Cordulegaster annulatus.

3. Enallagma cyathigerwm.

4. Pyrrhosoma minium.

x

LIST OF ILLUSTRATIONS

PLATE

V. DRAGON FLIES AND AQUATIC LEPI-

DOPTERA .

1. Cordulia enea.

2. Calopteryx virgo. Female.
3. Lestes sponsa.

4. Agrion puella. Female.
5. Hydrocampa nympheata.
6. Hydrocampan stagata.

VI. FISHES

1. Tue GupeEon (Gobio fluviatilis).

. Tue Mrynow (Leuciscus phoxinus).

Tue Dace (Leuciscus vulgaris).

. Tue Percu (Perca fluviatilis).

. Tue Sricxiepack (Gastrosteus aculeatus).

oF wb

Vil. FROGS AND TOAD

1. Tur Common Froe (Rana temporaria).
2. Tur Epix Froe (Rana esculenta).
3. Tue Common Toap (Bufo vulgaris).

Vill. NEWTS

1. Toe Great Warry Newt (Molge cristata).
2. Molge cristata. Female.
3
4

3. Toe Smoortn Newt (Molge vulgaris). Male.

. Molge vulgaris. Female.

ILLUSTRATIONS IN TEXT

CALCAREOUS SHELL— MAGNIFIED

. A compound Prorozoon (Magosphera planula)—Maante IED .
. Tourer cm1arepd Provrozoa (Infusorians) — MAGNIFIED
. Smicious SHELL or A Radiolarian

. JELLY-FISHES— EXAMPLES oF Coalenterates

. Toe Hypra— ENLARGED

Tue FEATHER STAR: AN Hichinestees

9. Tue Common Rortrer (Rotifer vulgaris) — Sawin D

To face p. 273

» 353

» 364

389

Male.

. THE SIMPLEST OF THE Protozoa (Ameba)—MAGNIFIED . : 3
. A Prorozoon (Globigerina bulloides) witH A PERFORATED

No anf, *»& &» WwW

FIG.
88.
89.
90.
91.
92.
93.
94.
95.
96.
97.
98.
99.

100.

101.

102.

103.

104.

105.

106.

107.

108.

109.

110.

111.

112.

113.

114.

115.

116.
117.

118.
119.

120.
121.

122.

LIST OF ILLUSTRATIONS

A Group or Vorticelle—MaGniFfiep , é
A Srncte Vorticella, ss SEEN UNDER A HIGHER POWER

Vorticella DIVIDING LONGITUDINALLY
Euglena P
Actinophrys sol— Hes MAGNIFIED
Stentor

SPICULES FROM VARIOUS SPONGES

THe Hypra—MaGniriep

THe HyprRa WITH DEVELOPING Bup

Hypra witH Ovary : F

THREAD CELLS OF THE Hypra — ieeieas MAGNIFIED

A Nematoid

Rotifer vulgaris

Floscularia cornuta

Stephanoceros .

Melicerta .

Brachionus urceolaris

Dinocharis pocillum

Tue Common Horse LEECH

DicestivE Tuse or LEECH : :

SecTion oF LEECH, SHOWING DIGESTIVE AND ne ous eae:

THe Mepicrnat LEECH ,

Plumatella repens—Portion oF A Goactes i ae

Tue FREsHWATER Musser (Anodonta cygnea) AS SEEN IN THE
AQUARIUM : : ; ‘ : : - :

Posterior ENp oF SHELL OF Anodonta, SHOWING THE Iy-
HALENT SIPHON WITH ITs TENTACLES, AND THE EXHALENT
SIPHON : : , 2 : na

SHELL OF inedontal cygnea, SHOWING THE ra AND
THE wumbones ; :

INTERIOR SURFACE OF THE LEFT v ALVE OF eiodoindi cygnea

Anodonta, LYING IN ONE VALVE, WiItH Upper Lope or THE
MANTLE REMOVED : ‘ : .

Section oF Anodonta, SHOWING THE DIGESTIVE Ter BE

THe Nervous System or Anodonta .

TRANSVERSE SECTION OF Anodonta ; : : 4

A Warer Swart (Planorbis corneus) AS SEEN WHEN CRAWLING
ON THE GLASS OF AN AQUARIUM

Tre Common Swat (Helix aspersa) ; ; ;

SECTION OF THE SHELL OF A SNAIL med: poritia); SHOWING
THE HOLLOW CoLUMELLA . ;

Sueiyt or Helix aspersa, SHOWING Mov TH AND ‘Pamsroun

xiii
PAGE
104
104
105
105
106
107
108
110
111
112
112
115
118
119
119
120
120
120
121
122
122
123
125

125

129

130
131

133
134
135
135

138
139

140
140

xiv LIST OF ILLUSTRATIONS

FIG. ; PAGE
123. Portion or THE Linevat Ripson or THE SNatL—Maeniriep 141
124. Section oF THE Heap or a Snatu (Helix aspersa) . ee
125. ANATOMY OF THE SNAIL . : : : 3 5 ‘ . 146
126. Spherium corneum. : : : : ; ; = Lael MEER
127. Spheriwm ovale. : ‘ : : : : : . ee
128. Spherium lacustre . ; : , : ; 3 a
129. Pisidiwm amnicum 2 : : : : ; : . 153
130. Pisidiwm fontinale—ENLaRGED . 3 : ; : Joe as
131. Pisidiwm pusillum—ENLARGED ; : : : . 154
132. Pisidiwm nitidum—ENLARGED . “ : , : es
133. Pisidium roseum—EnuaRGED. .. . «. «—. .. 154
134. Vatve or Unio Margaritifer, sHowINGc THE TEETH AND THE
MuscuLaR IMPRESSIONS . : : , : : sees
135. SuHett or Unio pictorwm, SHOWING THE TEETH. : <= 159
136. Anodonta cygnea , : : ; R : ; ot Lee
137. Dreissena polymorpha. : : : : ; = at:
138. Neritina fluviatilis . s : ; : ; , 2. s ) 68
139. Paludina vivipara . : ; : , ; ; -. 164;
140. Paludina contecta . : . : 2 , : . 64
141. Bithynia tentaculata . : : ; ‘ ; ; . 165
142. Bithynia Leachti—ENuarced . : : t. 166
143. Valvata piscinalis—ENLARGED é ; ; : =) 166
144. Valvata cristata—ENLARGED ° : : : = SG
145. Pianorbis lineatus—EN LARGED : : 2 " - wG9
146. Planorbis nitidus—ENuLaRGED . ; ; : ie
147. Planorbis nautileus—ENLARGED . : : : : « SFO
148, Planorbis albus—ENuaRGED. BRISTLES REMOVED . +). EO
149. Planorbis parvus . : ; : : : : ; me Ff.)
150. Planorbis spirorbis . d : ; = : , oo ot a
151. Planorbis vortex. : ; : : ; : : ; 70
152. Planorbis carinatus . ; ; : : ; " . ae
153. Planorbis complanatus . ; ; ; : 171
154. Planorbis corneus. (Sree auso Prater II, rie. 7) ; » Secs TERE
155. Planorbis contortus—ENLARGED . : ; ‘ ; o Ls
156. Planorbis dilatatus . , : : ‘ ; : ee toes," |
157. Physa hypnorum . ; ; : : ; ; ae et
158. Physa fontinalis : ; . : : ; ; a! need ee
159. Limnea glutinosa . : : : : ; : 7 . 174
160. Limnea peregra ; ; : ; ; : : cy eae
161. Limnea auricularia . : : ‘ : ‘ ; Pe
162. Limnea palustris : ; ; : ‘ : ; ie Ee

163. Limnea truncatula ‘ : P : ; , : + RTD

FIG.

164.
165.
166.
167.
168.

169.

170.
171.
172.

173.
174.
175.
176.
LT7.
178.

179.
180.
181.
182.
183.
184.
~185.
186.
187.
188.

189. }

190.
191.
192.

193.
194.
195.
196.

197.
198.
199.
200.

LIST OF ILLUSTRATIONS

Limnea glabra . : ; : ; :

Ancylus lacustris—NATURAL SIZE AND ENLARGED

Ancylus fluviatilis

Succinea putris

Succinea elegans : :

THe CrayrisH (Astacus Wuutina)

THe CrayrisH—Uprrer SIpE

Tue CrayrisH—UNDER SIDE. , : : : : -

THE FOURTH SEGMENT OF THE ABDOMEN OF THE CRAYFISH,
WITH APPENDAGE ON ONE SIDE . ‘ : : vars

Watkinc APPENDAGE OF CRAYFISH WITH Gr. ATTACHED -

LONGITUDINAL SECTION OF THE CRAYFISH . , : aad 2

THe FRESHWATER SHRIMP :

Asellus aquaticus :

Warer Fiera (Daphnia pay 2 a ate IED : ;

Cyclops quadricornis, FEMALE CARRYING THE EaG@ Sacs.
Auso THE LarvA—MAGNIFIED

A Cyclops VIEWED FROM THE SIDE

LEG or A SPIDER ;

Argyroneta aquatica AND ITs Nae ST ; .

A Water Mire (Hydrachna)—Macniriep

Bopy or an Insect—UNDER SIDE .

THe SraGes or AN INSECT. : :

SECTION OF THE Eye oF AN INSECT | eaeeces,

LrG or AN INSECT ; : ; P :

WrnG or AN INSECT, SHOWING THE Rays orn NERVURES .

TRACHEA OF INSECT, SHOWING THE SprraL THREAD

Nervous System oF AN Insect (BEETLE), SHOWING THE
CHAIN OF GANGLIA AND THE DOUBLE CENTRAL NERVE Corp.

Moura or Aa Bue

Hydrometra stagnorum :

Wire Rine anp Corron THREAD TO DEMONSTRATE THE ELas-
TICITY OF THE WatTeR Fim ‘ :

Tur THREAD PULLED BY THE ELASTICITY OF THE Fin.

Gerris gibbifera— ENLARGED

Gerris argentata— ENLARGED

Tue Heap or Gerris argentata, sHowInc THE BEAK AND
ANTENNA— ENLARGED : ;

Larva or A Ponp SKATER—ENLARGED

ForELEG or Gerris argentata—-EXNLARGED .

THe Water Boatman (Notonecta glauca)

Notonecta glauca witn WINGS EXTENDED .

xvi

FIG.

201.
202.
203.
204.

205.
206.
207.
208.
209.
210.
211.
212.
213.
214.

215.

216.
217.
218.

219.
220.
221.
222.

223.
224.
225.
226.
227.
228.
229.
230.
231.
232.
233.

234. °
235.
236.
237.

LIST OF ILLUSTRATIONS

Corixa Geoffroyi—ENLaRGED .

Corixa Geoffroyt, UNDER GR rae :

Nepa cinerea witH FORELEGS FOLDED :

ForELEG or Nepa—ENLARGED ; SHOWING THE DEEP GROOVE
WHICH RECEIVES THE TARSUS

Nepa cinerea with WINGS EXTENDED

Larva oF Nepa cinerea

Ranatra linearis

Naucoris cimicoides 3

Naucoris with WINGS EXTENDED ;

Heap or Naucoris, SHOWING THE Dic “Wetasens :

Podura ee ee :

Aquatic INsEcTS ; :

Larva oF Dracon Fuy, wirH ‘Mase’ EXTENDED

Mask or THE Dragon Fry Larva (Libellula) ss sEEN FROM
THE SIDE WHEN ONLY PARTIALLY EXTENDED—ENLARGED

THE SAME VIEWED FROM ABOVE

Pupa or Dracon Fiy.

DraGoN FLY EMERGING FROM THE Pur ee ; ;

Heap or Platetrwm depresswm—ENULARGED ; SHOWING THE
LARGE ComMpouND EyEs, THE OCELLI, AND ANTENNE

Heap oF Cordulegaster annulatus—ENLARGED

Heap or Calopteryx virgo— ENLARGED

Hinp Wixe or Cordulegaster innate Borate

Bopy or Cordulia @nea—ENLARGED ; SHOWING THE SEGMENTS
OF THE ABDOMEN :

THe ABDOMINAL eee OF ete Salen ‘2hes, See

Libellula quadrimaculata

Sympetrum vulgatum

Sympetrum scoticum

AE schna cyanea .

May Fry (Ephemera waligaiae

Larva or Hphemera—ENuaRGED

Popa or Ephemera—ENiLarGEeD

Stone Fry (Perla marginata)

An ALDER FLY AT REST. ;

THe Auper Fry with WINGS EXTENDED— Teen NATURAL
SIZE . ; ; ;
Tue Cappis Fry Phen ganea hemes: ENLARGED .

Cappis Cases

A Cappis Lays — Eee j ; : ,

Cappis Fry (Limnophilus bicolor)—ENuarGeEp .

PAGE
231
231
234

234
235
236
237
239
240
240
242
245
252

254
254
257
258

259
260
260
260

261
262
265
266
266
271
276
278
279
282
285

286
287
289
293
296

LIST OF ILLUSTRATIONS Xvll

FIG. PAGE
238. Cappis Fry (Leptoceros ochraceus)—SuiGHTLY ENLARGED . 297
239. THe Gwat—Larva, Pupa, Perrect INSECT EMERGING, AND

THE MALE AND FEMALE FLYING . E ; ‘ d - 3800
240. ScaALE OF THE GNAT . : ; . 301
241. OrGANS OF THE MOUTH OF THE iipeeats Sask Siathbeales . 301
242. Tue Eaa Rarr or THE GNatT—ENLARGED ‘ . 3803
243. Chironomus—ENLARGED . : : : ; Sits
244. A ‘BLoopworM,’ VIEWED FROM ABOVE Me eee ; ; . 307
245. Larva or Corethra . : ; ; ; Aon Lee
246. Tue Perrect Corethra . : : ; : : . 310
247. Stratiomys chameleon : ; : ; 2 : xe See
248. Larva or Stratiomys . P ; : < : ; . 312
249. Stratiomys furcata . : ‘ : : J : fa; eee
250. Fristalis tenax—SiiGHTLY ENLARGED . ae : . 313
251. Larva or Eristalis tenaz . : : - ; ou eee
252. ScaALES FROM THE WINGS OF Beans“ Macengeen - 317
253. PorTIoN oF THE WING oF A BUTTERFLY FROM WHICH SOME

OF THE SCALES HAVE BEEN REMOVED—-MAGNIFIED . aes SEE
254. Wine or A BUTTERFLY, THE SCALES HAVING BEEN REMOVED. 318
255. Cataclysta Lemnata . , : f F : : ee
256. Paraponysx stratiotata . - : , : . 320
257. ANTENNA OF Dyticus PRES eg Ores , ; cy ot eee
258. ANTENNA OF Gyrinus natator—ENLARGED . é ; . 323
259. AnTENNA OF Hydrophilus piceus (MALE)—ENLARGED - . 323
260. UnpER Sme or THE Bopy or Dyticus marginalis—

ENLARGED . ; p ‘ ‘ ; - . 3826
261. ForELEG or THE MALE Dimes aeneale Vasuak sem OO
262. Tarsus or Mate Dyticus—MaGniriep . = ; : . 328
263. Larva or Dyticus marginalis . : : ; : . . 3830
264. Unper Smpe or THE Heap or D. marginalis Larva—

ENLARGED. : ; , ‘ . 331
265. Hydroporus 12 pe ae ees F . ; - « 332
266. Agabus biguttatus—ENLARGED - . : . 832
267. Pelobius Hermanni—ENiLARGED : ; : ‘ - - 8338
268. Cnemidotus impressus—ENLARGED . : ; 3 . 833
260. Haliplus variegatus-—ENLARGED ; . . 333
270. Gyrinus natator—ENLaARGceD . . ; . 334
271. Larva or Gyrinus—ENuARGED . : ‘ . . 336
272. Hydrophilus piceus, Maun. f ; . . 337
273. Hydrophilus piceus, Mauw—Unper Sipe . - . 337
274. Foretea or FHydrophilus piceus, Femate : : . 338

275. Hydrophilus piceus, w1rH WINGS EXTENDED . » 889

XVili LIST OF ILLUSTRATIONS

FIG.

276. Larva or Hydrophilus piceus : : ; : . ;

277. Pura or Hydrophilus piceus . t ; . : :

278. Elmis eneus—ENLARGED : , : ‘ i ,

279. Polynema natans—ENULARGED . cre ’ ; fen

280. SKELETON oF A Fisu (PERCH) : ; : : : ;

281. Tue CrrecunaTIon oF Bnoop IN A FisH_ .. ; : +s

282. Tue River Lamprey (Petromyzum fluviatilis) : d

283. INTERNAL ORGANS OF ONE oF THE Physostomi (HERRING).

284. Ture Bieax (Alburnus lucidus) : : :

285. Tue Carp (Cyprinus carpio). é A ‘ s :

286. Tue Roacu (Leuciscus rutilus)

287. Tue Loacu (Nemachilus barbatulus) , :

288. Tue BuniHEap (Cottus gobio) : é : ;

289. Tue Youna TappoLE oF THE CoMMON Frog (Rana tempo-
raria)—ENLARGED ; SHOWING THE EXTERNAL GILLS Me

290. THREE-CHAMBERED Heart oF THE ApuLT FRoG—ENLARGED .

291. Toe Unper Srpe oF THE TADPOLE OF THE FROG, SHOWING
THE COILED DIGESTIVE TUBE, THE SUCKERS, THE INTERNAL
Ginus, AND THE Resprratory APERTURE—ENLARGED .

292. Eacs oF THE FROG, JUST LAID

993. Eacs or THE FRoG, A FEW HOURS AFTER LAYING ,

294. Vartous STAGES OF THE PRocESS OF THE SEGMENTATION OF
THE YOLK—MAGNIFIED . ; ; : : bu

295. Section THROUGH A FRoG’s oe. SHOWING THE INTERNAL
ARRANGEMENT OF THE CELLS—MAGNIFIED . :

296. A SEcTION THROUGH THE EMBRYO AT A LATER STAGE, SHOW-
ING THE THREE LAYERS oF CELLS—MAGNIFIED : bate

297. Tue DEVELOPMENT OF THE FROG EMBRYO AS OBSERVED WITH
THE UNAIDED EYE—NATURAL SIZE : : : ; ‘

298. Tue Youna TADPOLE SHORTLY BEFORE HatcHInc—MAGNIFIED

299. A Group OF VERY YOUNG TADPOLES . ; é . Nees

300. TADPOLES IN VARIOUS STAGES—-NATURAL SIZE : : :

301. Tue TappoLe wire irs Lives In Progress or DEVELOP-
MENT—THE FRONT PAIR BEING STILL CONCEALED UNDER THE
GILL COVERS

302. Youna Froas . ; ; : : : , ; : :

303. THe SKELETON OF THE FroG . ; ‘ A ‘ Lets

304. Heap or Rana temporaria—UPrER SURFACE

305. Toncvur or A FRoG

306. BLoop-cELLS OF THE FRoG . : : : P ;

307. CIRCULATION OF BLoop IN THE WEB oF A FRoG’s muh ye

PAGE
341
342
343
345
347
348
351
352
353
354
355
356
359

362
362

363
365
365

366

366

367

367
368
368
369

370
371
373
376
379
380
380

LIST OF ILLUSTRATIONS

FIG.

308. THe Urrer Sipe or THE Heap or THE Mate Rana escu-
lenta, SHOWING THE VocaL SAcs INFLATED : ;

309. Youna Newt (Molge vulgaris), JUST BEFORE THE FINAL DIs-
APPEARANCE OF THE EXTERNAL GILLS

310. Mane anp Femate Cristata—REDUCED IN SIZE : ?

311. THe Common Newt (Molge vulgaris), MaLE anp FEMALE—
NATURAL SIZE .

Xix

PAGE

381

392
395

397

we = on wel, Ue ee
set an tat ae
F ' a : 7 Hs —

y .* 4 a7 i hen i oe

v4 Ta en

tas mT f , <i

PART I
THE COLLECTOR’S WORK

CHAPTER I
INTRODUCTION

NoruHinG need be said by way of encouragement to those who have
already examined a few hauls from a standing weedy pool, or who
have gathered the moving forms that inhabit the overgrown banks
of ditches and streams. The variety of living beings that frequent
these places is so great, and their remarkable antics are so pleasing,
that each dip of the net supplies the stimulus for the next, and each
outing spent in searching for aquatic life intensifies the love of the
pursuit.

It may be thought that pond and stream lose their charm for
the naturalist who, from long experience, has already become
acquainted with what they are capable of yielding; but this is not
so. Who can say that he has even seen all the species that frequent
a stagnant pool? Or who can aver that he is thoroughly instructed
as to the life histories and habits of even the commonest forms that
are taken at almost every dip of the net? In fact, it is just here
where the attraction lies. Unknown beings are continually making
their appearance, and the old and apparently well-known friends
of the collector are ever and anon exhibiting some new phase, or
displaying some peculiar habit hitherto unnoticed. And it is
this remarkable variety of aquatic forms, the equally remarkable
diversity of their movements, and the almost continual appearance
of something new, that puts pond-hunting at least on a level with
some of the most popular pursuits of the naturalist.

Let us briefly survey the whole animal kingdom, noticing the
broad features of classification, and then see how far the various

B

Ce

2 THE COLLECTORS WORK

classes are represented by the inhabitants of our ponds and
streams.

The animal kingdom is divided into several groups, often termed
sub-kingdoms, each one of which includes a number of creatures
that possess certain characteristics which are common to all, and
by which they may be distinguished from the members of the other
groups.

As may be expected, no two authorities entirely agree in the
details of their arrangement of the multitudinous and varied forms
of animal life; but we shall confine our attention to the broad
principles of classification only, and consequently shall not tread
far on debatable ground.

The groups above referred to are eight in number, seven of
which include animals that possess no internal skeleton of bone,
though they are frequently supported by deposits of limy, silicious,
or horny matter, forming in some cases a well-developed external
covering. These seven groups constitute a very extensive and
varied division of the animal kingdom known as the Invertebrata,
or animals without backbones; and the remaining group—the
Vertebrata—include all creatures that have internal bony skeletons,
the main portion of which is the backbone or vertebral colwmn.

The following is a tabular arrangement of the eight groups,
commencing with the simplest forms of life, and taking each of the
others in the order of complexity of structure.

Animals without backbones :

1. Protozoa—Simplest forms.

2. Poriferata or Polystomata—Sponges.

3. Calenterata—Jelly-fishes.

4, Echinodermata—Starfishes, &c.

5. Vermes—Worms.

6. Mollusca—Mussels, Snails, &e.

. Arthropoda—Animals with segmented bodies.

Animals with backbones:
8. Vertebrata—Fishes, Reptiles, Batrachians, Birds, Mammals.

The first of these groups—the Protozoa—contains the lowest
forms of animal life, the bodies of which consist each of a minute
speck of transparent substance that generally exhibits no differentia-
tion of structure. ‘There is no internal cavity to represent the body
cavity of higher forms, and no nervous system, nor are there any

INTRODUCTION 3

special organs to perform the functions of digestion, circulation, or
respiration.

These creatures, in fact, are mere specks of living jelly, often
without any kind of hard support whatever, but sometimes protected
by a perforated shell of calcareous
matter, or a delicate network or basket-
work of silica.

Most of the Protozoa move about
freely by means of temporary prolonga-
tions (pseudopodia) of their jelly-like
substance. These ‘ false feet’ are some-
times short and blunt, and sometimes pats Sader ease yi
are long and threadlike. Their mode SR ea
of feeding is strange. Having come
in contact with an approved morsel, the creature will surround it
with two of its short temporary feet, or pull it towards its body by
means of some of its long and slender ‘arms.’ The gelatinous sub-
stance of its soft body then extends itself round the desired particle,
which is thus brought within the organism; and, there being no
special digestive organ, any
part of the body is capable of
digesting the meal.

Equally curious is the
method by which these
simple animals multiply. As
a rule they increase by a
division of their bodies
each one dividing into two,
these two afterwards dividing
again, and so on. But some
develop buds, which break
away and soon reach matu-
rity.

The Protozoa include a
number of the inhabitants

of stagnant pools, some of Fic. 2.—A Prorozoon (Globigerina
which will be described in bulloides) WITH A PERFORATED CAL-
a future chapter. In addi- CAREOUS SHELL, MAGNIFIED 6K

tion to these, the group in-
cludes the Rhizopods—a class of marine animals, the bodies of

which are protected by beautiful little shells; and the Radiolaria,
BY

4 THE COLLECTOR'S WORK

also marine, the delicate netted silicious skeletons of which are
commonly found among the dredgings of the ocean. ‘There are
also parasitic members of the Protozoa that live and feed within
the bodies of insects, worms, and other creatures.

Fic. 3.—A compounp Pro- Fic. 4.—THREE cImnIATED PROTOZOA

rozoon (Magosphera (Infusorians), MAGNIFIED
Planula), MAGNIFIED

The second group—Poriferata or Polystomata—includes the
Sponges. These also are very simple animals, but differ from the
Protozoa in that they have a body cavity, with
large outlets and many smaller inlets, and are
surrounded by a jelly-like wall that consists of
two layers. The delicate structure of the body
is supported by a skeleton which is sometimes
horny and fibrous like that of the common toilet
sponge, or is calcareous or silicious.

These creatures multiply by division, and
may even be increased artificially by cutting
them into pieces, as each piece soon develops
into a complete sponge.

Most of the species are marine, and in several
cases their skeletons are familiar objects of
beauty, notably those of Venus’s flower-basket

and Neptune’s cup. Several of them are
Fic. 5.—SILIcIous bi ; ea d
Suen, or a colinson o jects on our own shores, and one or
Radiolarian two species inhabit our ponds and canals.

The third group is the Calenterata. It
includes a great variety of animals which, together with those of
the following division, form the ‘chaotic group’ that. was once

|
|
.

INTRODUCTION 5

designated by the term Radzata, their bodies being all formed of
a number of parts arranged symmetrically round a common
centre.

The Calenterata have bodies of a gelatinous, gristly, or leathery
nature, and the body cavity has only one opening—the mouth.
This opening is surrounded by contractile arms or tentacles, by
means of which the creatures seize their prey, and which are occa-
sionally used for locomotion. The tentacles are also provided with
stinging cells to paralyse their victims.

Oye
TRY

ant

Fic. 6.—JeLLY-FISHES—EXAMPLES OF Calenterates

In many instances a portion of the body cavity is partitioned
off to serve as a stomach, but in some of the simpler forms the
general cavity itself is the digestive organ.

The members of this group are mostly marine, and include the
Sea Firs, which live in colonies, several individuals being attached to
a common stalk; the ‘ Jelly-fishes’ so commonly washed upon our
shores ; and Sea Anemones and Corals, some of which are solitary,
while others live in colonies, some having stony skeletons and
others being without any kind of hard support.

The Cwlenterata are very poorly represented in fresh water, but

6 THE COLLECTORS WORK

they include the interesting little Hydra of stagnant pools which
will be described later on.

The Echinodermata, or spiny-skinned animals, will not claim
any of our attention since they are entirely marine. The group
includes Starfishes, Sea Urchins, and Sea Cucumbers, all of which
have hard spines projecting from their bodies. Their bodies have
also a radiating symmetry, and contain a system of water tubes
which serve as a means of locomotion.

The fifth group is the Vermes or Worms, distinguished by their
soft and elongated bodies, which are formed of a long chain of ring-
like segments of similar structure.

The animals of this division have generally a distinct nervous

Fic. 7.—TuHe Hypra, ENLARGED Fic. 8.—Tue Fratruer Star:
AN EH chinoderm

system, consisting of a few little masses (ganglia) of nerve sub-
stance round the fore part of the digestive tube, and a nerve cord
passing from these along the body beneath the same tube. They
are also frequently provided with a system of blood-vessels, but,
although the main vessel may be contractile, there is no true heart
for the propulsion of the blood.

This group is fairly well represented in fresh water, but the
most interesting as well as the most beautiful species are to be
found among the marine members. It includes the somewhat slug-
like Turbellarians, some of which inhabit stagnant freshwater
pools; the parasitic Tapeworms, Flukes, Threadworms, &e., that
commit their ravages within the bodies of man and beast; the

INTRODUCTION 7

remarkable little Wheel-animalcules (Rotifers) of stagnant water ;
marine Squirts ; Leeches ; the tube-building worms of the sea shore ;
the Sea Mouse ; the Earthworm ; and the gregarious Moss Polyps, a
few of which live in fresh water.

It will thus be seen that
the Vermes is a very exten-
sive group, containing a
great variety of animals,
many of which are so charac-
teristic that they have been
placed by some eminent natu-
ralists in separate divisions.

The sixth group — Mol-
lusca—is one full of interest
to the pond-hunter, as it in-
cludes a considerable number
of creatures that are very
ornamental and even almost
necessary in the aquarium,
and whose shells are in them-
selves worthy objects of
study.

Most of the Molluses have
not the slightest trace of an
internal skeleton, but many :
of them are protected exter- yg, 9—Tue Common Fic. 10.—Tue
nally by a calcareous shell. Rortrer (Rotifer Lrercu
Their bodies are soft, and U#lgaris), MAGNIFIED
generally covered with a soft
but tough and thick tunic or mantle. They all have a digestive
canal, and many of them are provided with a large number of small
teeth which they use to rasp away the solid matter on which they
feed.

The nervous system consists of a ring of nerve substance round
the front portion of the digestive tube, and many members of the
group have special sense organs. They have alsoa contractile heart
with two or more cavities, but have no system of special vessels for
the conveyance of blood, that fluid being forced into and through
the spaces between the various organs.

There are three classes in this group. The first contains the
two-shelled or bivalve molluscs, such as oysters and mussels.

8 THE COLLECTOR'S WORK

These have no. heads, and breathe by gills. Many of them are
freshwater species. The second class contains the headed molluses,
such as limpets, snails, and slugs. Most of these are enclosed in a
single shell, like the common garden snail; but some have none at
all, and others only a rudimentary shell—a small calcareous plate,
or, perhaps, only a few granules beneath the skin. The aquatic
species, which include freshwater snails, breathe by gills; and
those which live on land have a breathing chamber, corresponding
with the lungs of higher animals, communicating direct with the
air. The third class contains the more highly organised nautili,
cuttlefishes, squids, and other marine species.

The next sub-kingdom—the Arthropoda—is the last and most
highly developed of the Invertebrates. It is, moreover, a very

Fic. 11.— NeErvous System Fic. 12.—Cycuoprs, wITH Its
or AN Arruropop (BEETLE), Kae Sacs, MAGNIFIED

SHOWING THE CHAIN OF GAN-
GLIA, THE DOUBLE NERVE
Corp, AND THE SMALLER
NERVES

extensive group, and contains a variety of creatures of very great
interest to the pond-hunter. Their bodies are covered with an exo-
skeleton of hardened skin, sometimes of a horny character, and
sometimes calcified by deposits of carbonate of lime. In each case,
too, the body consists of a number of segments, movable one on the
other, and bearing each a pair of appendages, some of which may
be described as limbs, while others serve the purpose of jaws or
mandibles, or develop into long and slender antenni, or constitute
a stalk on which the eye is mounted. Most of the arthropoda have

INTRODUCTION 9

a heart and blood-vessels, the former being divided into chambers
by means of valves; and also a distinct system of organs for respira-
tion. The nervous system is generally of a complex character, con-
sisting of a large ganglion, corresponding to the brain of vertebrates,
which supplies nerves to the organs of the senses; and a chain of
ganglia extending through the body.

This very extensive sub-kingdom contains four classes :

1. Crustacea—Crabs, Lobsters, «ce.

2. Arachnoidea—Spiders and Mites.

3. Myriapoda—Centipedes and Millepedes.

4. Insecta—Insects.

The Crustaceans are nearly all aquatic, and breathe either by
gills or by the absorption of air through the surface of the body ;
and they pass through a series of changes during
their early stages, the young animal, known as
the larva, being often very unlike the adult. The
freshwater species include crayfishes, fresh-
water shrimps, water fleas, and cyclops, all of
which will be hereafter described.

The Arachnotdea may be known by their en a ee
four pairs of walking legs, and by the division of — Myre, waGuierep
the body into two distinct parts, usually united
by a narrow waist. The foremost of these divisions consists of the
combined head and thorax, and the other of the limbless abdomen.
The familiar garden and house spiders are typical
examples; and the mites that feed on our cheese
and sugar, the ‘itch insect’ and ticks, and the*
chelifers that find a home between the leaves of old
books, are also members of the class; but the only
species that directly concern us now are the aquatic
spiders and mites.

The next division of the Arthropods—Myria-
poda—contains the few centipedes and millepedes
that live in damp places, under stones, or in
rotting wood. They have elongated bodies, com-
posed of a large number of segments, each of which
bears a pair of short jointed limbs. They obtain Fie. 14.—Cen-
the air they require, direct from the atmosphere, TIPEDE (Li-
through a system of air tubes (trachee) that open —_*/#0btus)
on the sides of the body.

We now reach the interesting class Insecta, which contains such

10 THE COLLECTOR’S WORK

a host of living creatures, with such great diversity of habits, that it
is represented everywhere and at all seasons of the year. Some of
its members are almost purely aquatic, spending only a few days or
hours of their whole existence on land or in the air; some are
purely terrestrial, living either under the surface of the ground, or
in sheltered chinks and crannies above, and feeding on exposed
animal or vegetable substances. A large number are provided with
organs of flight for a longer or shorter period.

Insects may be known by the division of their bodies into three

i

)

i

Fic. 15.—Tue THREE Sraces or AN Insect (THE BLAck WATER
Bertie, Hydrophilus piceus)

a, larva; b, puna; c, imago

more or less distinct parts—the head, the thorax, and the abdomen.
They have also three pairs of walking limbs. The thorax is com-
posed of three annular segments, each of which bears one pair of
legs; and, in the case of the aérial species, the middle segment
bears a pair of wings, while sometimes an additional pair is attached
to the hindermost segment. The visual organs are a pair of large
compound eyes, in addition to which there is frequently a cluster of
simple ones. The mouth is provided with a strong pair of chewing
jaws, or is adapted for the suction of liquid foods.

INTRODUCTION 11

The above remarks apply only to the perfect insect or imago ; for
inseets, like crustaceans, pass through a series of changes before
they finally reach maturity. In many cases they assume three
distinct forms—the larva or grub, the chrysalis or pupa, and the
perfect tmago already mentioned. The larva is generally a very
voracious feeder, growing rapidly, and undergoing a series of moults
or changes of the skin as the latter becomes too small for its expand-
ing body. When fully grown it ceases to feed, and its next moult
leaves it in the form of a pupa, in which state the insect is often
quiescent, taking no food for a period varying from a few days to
many months. At the appointed time, however, the pupal skin
bursts, and the perfect insect emerges. In some insects these
metamorphoses are not well marked, and in others there are no
such changes at all.

The various phases of insect life form such a marked feature
of the natural history of our ponds and streams, that it will be
advisable here to give a short description of the different orders of
this class, that we may realise to what extent they enter into the
scope of our present work. In so doing we shall begin with the
lowest forms, and end with the most highly organised and intelligent
division.

Order 1. Rhynchota or Hemiptera.—The insects of this order
do not undergo any distinct metamorphoses, hardly any difference
being observable between the young and the
mature. Most of them have mouths adapted
for suction, and some are provided with
needle-like organs by which they pierce the
bodies of the creatures on which they feed.
The order includes wingless parasites such as
lice and bugs, also aphides or plant lice,
which are often winged. The aquatic species
include the water gnats, boatmen, and water =‘ Fc. 16.—A Waren
scorpions of our ponds and streams. 7k oe pend

Order 2—Thysanura—contains the little sige lin BE 0
sugar lice and the springtails, which leap
vigorously by means of a pair of elastic bristles at the tip of the
abdomen. Nearly all are terrestrial in their habits, and most of
them live under the cover of stones, dead leaves and moss, or in
dark outhouses and cellars. Their metamorphoses are not complete,

Order 3. Orthoptera.—There is a great diversity of opinion as
to the extent of this order. It is always made to comprise the

12 THE COLLECTORS WORK

cockroaches, crickets, and grasshoppers. Earwigs are also included
by some, while others place these in a separate order (Huplexoptera)
by themselves ; and even the dragon flies are sometimes placed
with the Orthoptera, or straight-winged insects. The chief
characteristic of the order is the structure of the wings. The front
pair are horny or parchment-like, and the hind pair are folded
beneath them, when not in use, something after the manner of a
fan. We shall consider the dragon flies as belonging to the next
order, and thus there are no aquatic Orthoptera for our con-
sideration.

Order 4.—The Newroptera, or nerve-winged insects, are distin-
guished by two pairs of wings, each wing consisting of a very thin
and transparent membrane, supported by
a fine network of delicate nervures. ‘The
hind wings are sometimes folded as in
the Orthoptera. The metamorphoses are
complete; and in many instances the
pupa is quiescent. All are provided with
horizontal jaws for chewing in _ the
Fic. 17.—Scorrton Fry larval state, but in the perfect state the

organs of the mouth are sometimes rudi-
mentary, so that the insect has no power of taking food of any
kind. The order includes snake flies, scorpion flies, dragon flies,
may flies, and stone flies. The last three of these spend the greater
part of their existence in ponds or streams.

Fic. 18.—Cappis Fry (Phryganea Fic. 19.— Toe Drone Fy
minor), TWICE NATURAL SIZE (Hristalis tenax), ONE OF THE

Diptera, SLIGHTLY ENLARGED

Order 5. Trichoptera.—This order comprises the caddis flies, and
is so named because the wings of these insects are clothed with

INTRODUCTION 13

hair. The larve and pupe are aquatic, and live in cases which
they construct of materials that they find in the water.

Order 6. Diptera.—The Diptera, or two-winged insects, include
a host of species, the larve of which have no legs. The house fly
and the bluebottle are very familiar examples; and gnats and
some others are aquatic during their earlier
stages. Fleas are sometimes included in this
division, but their wings are only rudimentary.

Order 7.—The Lepidoptera, or scaly-winged =
insects, comprise many hundreds of species, Frc, 20.—A Morn

commonly known as butterflies and moths. A WITH = AQUATIC
few are aquatic in the larval stage, and will Larva (Hydro-

: : i campa_ stagna-
therefore be considered in their place.

lis)
Order 8. Coleoptera, or horny-winged in-

sects.—These are popularly known as beetles. Their outer wings
are hard and of a horny character, and the hind pair, which are
membranous, are folded beneath these. Several species spend a
portion or the whole of. their existence in water.

Order 9. Hymenoptera, or membrane-winged insects.—Very

few of these are of aquatic habits. They have four membranous

Fic. 21.—Awn aquatic BEETLE Fia. 22.—A nyMENoPTEROUS INSECT
(Agabus biguttatus), (Saw Fry), ENLARGED
THREE TIMES NATURAL SIZE

wings, supported by only a few nervures. The mouth is provided
with strong mandibles for chewing, as well as a tube for suction.
The most familiar examples are ants, bees, and wasps, all of which,
and especially the first named, are remarkable for the degree of
intelligence they display.

14 THE COLLECTOR’S WORK

We now reach the last group—the Vertebrata—which differs in
many important particulars from all the preceding. The main
characteristic is that implied by the name—the presence of a back-
bone or vertebral column. In some of the lower species, which
may be looked upon as connecting links between this division and
the higher invertebrates, the vertebral column is not of true bone,
but consists of gristle, and is the only representative of what, in
higher forms, constitutes the main axis of a complicated and highly-
developed internal bony skeleton.

The backbone generally consists of a number of separate bones,
all jointed together into a hollow column, through which runs the
great nerve called the spinal cord. This cord is continuous with
the brain, which is usually enclosed in a bony skull. And here we
observe one of the very important distinguishing features between
the vertebrates and the higher invertebrates, for while in the former
the great axis of the nervous system lies in a bony canal close to
the dorsal surface of the body, and the large body cavity containing
the organs of digestion and circulation lies in front of or below it,
in the latter the chain of nerve masses lies along the front or lower
part of the body, in the visceral cavity itself. And, again, while in
the vertebrates the limbs (which are never more than four in
number) are usually directed towards the visceral cavity, in the
arthropods they are directed from it. Another interesting differ-
ence lies in the arrangement of the jaws, which work horizontally
in the arthropods and in a vertical plane in the vertebrates.

The vertebrates are divided into five classes—Pvisces (fishes),
Reptilia (reptiles), Amphibia (amphibians), Aves (birds), and
Mammalia (mammals). .

As regards the fishes, the freshwater species alone are so
numerous that it would be impossible to deal with all of them
satisfactorily in the space at our disposal, so we shall confine our
attention to a few of the smaller ones that are suitable for the
aquarium.

None of the few British reptiles is really aquatic, but the
species of amphibians (frogs, toads, and newts) are so few that we
shall describe them all.

Many of our birds and mammals are aquatic in their habits, but
the former have already been ably dealt with in a recent volume of
this series, and the latter are to be considered in a forthcoming

work,

-

CHAPTER II
ON COLLECTING IN PONDS AND STREAMS

HAVING now become acquainted with the broad principles of the
classification of animal life, we must direct our attention particularly
to the study of those living beings that form the population of our
ponds and streams, and to this end we make preparations for an
excursion to the neighbouring standing and running waters in order
that we may watch the habits of the creatures in their haunts, and
secure such as may be desired for further observation and study
during our leisure hours at home.

The appliances required for this work are of a very simple cha-
racter, and will not present any great difficulty in the manufacture
to those who would prefer to make their own, and it will hardly be
necessary to state that every requisite may be obtained with a
minimum expenditure of time and trouble by those who prefer to
purchase them from the dealers in such commodities.

In the present chapter we shall deal only with the apparatus
for use in the collection of those forms of life that are of such a size
as to render the use of the lens or microscope unnecessary except
for the purpose of discerning details of structure or of closely study-
ing certain movements, which work, by the way, will be better done
at home; and then we shall, as a matter of convenience, devote
the following chapter especially to the smaller species. With this
explanation we will proceed to enumerate and describe the require-
ments for general work.

These are: (1) a net for capturing insects on the wing; (2) a
strong net for catching the inhabitants of the water; (3) a scoop or
scraper ; (4) a dredge for collecting the aquatic animals that live on
the bottom ; (5) a bait-can for the conveyance of pond weeds and
of live specimens that require more or less water during transit ;
(6) a number of chip and pill boxes to be carried in a satchel or one
or two large pockets ; and (7) a walking stick.

16 THE COLLECTORS WORK

We fancy we see the look of astonishment on the face of the
reader as he runs down this rather long list of items, and imagines
himself, in heavy waterproof boots, disfigured with bulging coat
pockets, and laden like a beast of burden with all these articles
of luggage; and when we further inform him that he may also
furnish himself with a rod and line, a supply of hooks, and a box of
bait, we can picture his growing disinclination to take up the study
of the animal life of our ponds and streams.

But did we say that all this paraphernalia would be required on
each of his excursions? No, certainly not. In fact, he will find it
far more convenient, as a rule, to restrict his modes of procedure,

Fic. 23.—NetT For INSECTS ON THE WING

and to visit favourable spots a second, and, perhaps, more times in
order to carry out those methods of attack that were unattempted
or only partly worked on the first visit. Thus, it will generally be
advisable to fix a day for dredging only ; and on another occasion,
when the angling rod is brought into requisition, not to attempt
much other work. But these are matters to be left in the hands of
the operator, and to be regulated according to his powers of endu-
rance and other circumstances. But to return to the apparatus for
outdoor work.

First, the nets. One is the ordinary kind used by lepidopterists

ON COLLECTING IN PONDS AND STREAMS 17

for the capture of butterflies and moths. It consists of a deep leno
bag, with no corners, sewn to a strip of calico that covers a light
ring of wire or cane, which is fixed by means of a ferrule to the end
of a walking stick. This will be required for securing dragon flies,
caddis flies, &c.; also those few species of moths that frequent
ponds, and whose larve feed on aquatic plants.

The second net must be much stronger, for it has to withstand
the friction against dense masses of weeds and the bottoms of ponds

Fic. 24.—Ponp NEt

and ditches. The ring must be of stout wire, and the bag, which
must not be deep, of book muslin. It need not be large, a diameter
of about nine inches being sufficient, but must be mounted on a
strong stick.

Even this net will sometimes show early signs of hard wear, and
it is often advisable to use a metal scraper or scoop for the rougher
work among pond weeds and the herbage of banks ; and this appli-
ance has the additional advantage that its bare rim will readily
remove those’ creatures that stick fast to the under surfaces of
aquatic plants, and which would be passed over by the rounded and

Fic. 25.—Tur Scoop orn ScRArer

covered ring of the net. It may be made of a hoop of sheet zine,
about two inches wide, with a bottom of fine gauze, and with a
ferrule to receive the stick.

The dredge is necessary in order to secure those larvie and
molluses that live in or on the mud at the bottom, or that attach
themselves to stenes in the beds of streams. Of course some of
these may be secured by means of the pond net if it be well scraped
along the bottom, but this is useless in the case of those species that

6

18 THE COLLECTORS WORK

lie at the bottom of rather deep water, and of the larger molluscs
that are to be found in large ponds at some distance from the banks.
I have seen dredges of a circular form, just like the ordinary pond
net, but with a heavier ring; this, however, is hardly satisfactory,
since only a small portion of the circumference of the ring can play

Fic. 26.—THe Triancuuar DREDGE

on the bed of the pond or stream. A triangular dredge (fig. 26) is
very much better, for as it is pulled over the bottom it naturally
settles on one of its sides, and thus covers considerable ground.
An oblong form (fig. 27) is also very good, and this may be attached
to the line either by three strings—one at each end of one side, and
another at the middle of the opposite side—or by four—one at each
corner.

The weight of the dredge is a matter for consideration, and must
vary according to the nature of the pond or stream to be worked.

Fic. 27.—Tue Opstonc DrepGE

If it is to play over a bed of soft mud where there are but few light
weeds to intercept its path, then the frame need not be very heavy ;
but if it is required for work on a stony bottom or among dense
herbage the weight must be increased. Thus it will be necessary
to supply oneself with one or two weights that may be readily at-
tached or removed according to the varying circumstances. I know

ON COLLECTING IN PONDS AND STREAMS 19

of nothing to answer this purpose so well as a few pieces of lead or
‘compo’ pipe that have been sawn through longitudinally on one
side. These are easily opened and closed, and may be readily
placed over the frame of the dredge when required, and as readily
removed when a lesser weight is advantageous.

A dredging hook is exceedingly useful at times. Large aquatic
plants and dense masses of weed that harbour water snails and other
creatures, and which are too firmly rooted
to be pulled in by the dredge, may often be
easily secured with a hook. Some form of
this implement is, I believe, to be obtained
from the dealers in naturalists’ requisites ;
but a very satisfactory one may be easily
made as follows: Procure three ordinary
galvanised meat-hooks from the ironmonger.

These are hooked at both ends. Straighten

out one end of each, and bind all three

together with many turns of stout copper

wire, leaving a double or treble loop of the

wire at the straight end to take the string.

Then, if you know just a little of the tinman’s Fic. 28.—TuHeE
art, strengthen the whole by running a little Dreveinc Hook
solder between the coils.

The bait-can need hardly be described, as everybody must be
familiar with it; and, in a case of emergency, there will never be
any difficulty in procuring a convenient substitute.

The chip boxes will be exceedingly useful, indeed almost indis-
pensable, for the conveyance of the smaller and more delicate shells,
and for small creatures of any kind that may be carried home alive
without water. A good supply of these should always be at hand,
as well as a number of glass-bottomed pill boxes of various sizes for
the accommodation of the winged insects that are caught with the
net.

If it is intended to capture fishes the outfit must be arranged
according to the nature of the specimens sought and the use to be
made of them. Many small species for the aquarium may be easily
caught with a net, and so may young specimens of the larger kinds.
A strong net well worked among the weeds of ponds and small
streams or along weedy banks of rivers will supply you with many
captives, and a dredge pulled rapidly along the beds will ‘ bag’
bottom fish such as the loach and the gudgeon ; and if these are to
be taken home alive the can must be large enough to accommodate

9

Ca

20 THE COLLECTORS WORK

them with comfort and to hold sufficient water to supply them with
oxygen for respiration during the homeward journey.

The larger fishes and those that inhabit deep water are to be
taken only by means of the hook, and as such will generally be
required for immediate study or to preserve for a permanent collec-
tion, there will be no need for the can.

Information respecting the habits of some species, such as will
be likely to add to the success of the collector, will be given in the
chapter devoted especially to the study of the fishes of our ponds and
streams.

All specimens taken home alive must of course be removed
from their confined quarters as soon as possible after your return ;
and to this end it is advisable always to have suitable accommoda-
tions quite ready for them before the start is made. Large and ex-
pensive glass aquaria are not at all necessary for this purpose, but
for the help of those who desire to do the thing in style, full direc-
tions will be found in the fourth chapter respecting the construction
stocking, and management of permanent aquaria.

It would be quite a mistake, however, to suppose that such
aquaria have even the slightest advantage over the rudest extempore
acconunodation that may be provided out of the utensils to be
found in every household, at least to the aquatic creatures them-
selves; and the only benefits to the owner are the possibly orna-
mental character of the aquatic home and the greater facilities for
observation. Indeed, we shall have to learn that the ruder accom-
modation afforded by tubs, pans, jars, &c. are really better for our
captives, being more in accordance with the character of their
natural haunts and, consequently, more in harmony with their
habits and likings.

This being the case, we ought to have no difficulty whatever in
providing a very satisfactory series of utensils, properly supplied with
gravel and fresh water, before starting on the tour of collection.

Nothing is better than a commodious tub for fish, frog spawn,
tadpoles, newts, &c.; bearing in mind the necessity for a second
similar utensil if among the captives there are those which would
prey on others. Aquatic molluses, crustaceans, spiders, and insects
will always do well in earthenware pans or small wooden tubs,
attention being paid to the precaution just mentioned. All the
small species—such as the small molluscs, larvee of insects, water,
beetles—and all the lower forms of aquatic creatures may be placed
in jars of convenient sizes, glass jars being employed for all minute

ON COLLECTING IN PONDS AND STREAMS 21

creatures as well as for those whose habits and structure are to be
the subject of close and immediate study.

So much, then, for the appliances for and the preparations pre-
ceding the hunt. Next let us briefly consider the two problems
‘When ?’ and ‘ Where ?’

The former question is easily answered ; for, although it may
be sometimes necessary to consult the season when a special expedi-
tion is to be made in search of some particular species, the hunter
of ponds and streams is sure to find something of interest at any
season of the year, the only barrier in his way being the thick
covering of ice that forms in the occasional event of a prolonged
frost. Every month of the year will supply material for an en-
thusiastic observer ; and while during the three genial seasons—
spring, summer, and autumn—fresh water is everywhere teeming
with varied forms of life, the bleaker months of winter will always
yield more than sufficient to satisfy the most ambitious lover of
Nature. Many a time have I been agreeably astonished at the
results of a few hours’ work on a mild day in December, January,
or February, and have had the satisfaction of knowing that my
boxes and other utensils were all well stocked with the fruits of my
labour. Even when the water itself has seemed almost devoid of
life, a small dredge and a ‘scraper’ have often been the means of
securing abundance of living beings from hidden weeds and a muddy
bed.

The second question—* Where ? ’—is disposed of almost as easily
as the first. Where shall we not try our luck? Here is the diffi-
eulty—if difficulty it can be called—to find a pond or stream,
large or small, that has nothing to yield. The tyro will probably
find his labours well repaid if he travels no further than the nearest
of the neighbouring ponds and ditches; and it is not until he has
made himself fairly we]l acquainted with the very common forms
of aquatic life that he will find much advantage in rambling to
distant spots in search of the rarer and more local species.

Still there are ponds and ponds, and streams and streams ; some
literally swarming with life of all kinds, and others almost barren.
A pond situated in the shade of a dense wood, and particularly if it
is surrounded by tall trees, is not likely to be very productive. The
abundance of decomposing vegetable matter, especially in the
autumn, renders the water extremely putrid and poisonous, so much
so that the first plunge of the net liberates a volume of the most
offensive gases ; and the feeble light that falls upon the water is no

22 THE COLLECTOR’S WORK

sufficient to support the pond weeds which would absorb the noxious
products of decomposition and set free the oxygen necessary for the
existence of animal life.

A luxuriance of vegetable growth may generally be regarded as
a sure sign of the presence of animal life; and a pond so densely
covered with duckweed that the water itself is almost completely
hidden from view will often prove a veritable treasury to the col-
lector.

Streams also are very variable in the productiveness of their
animal life, but it is rarely that we meet with one that is almost or
absolutely unproductive unless it is contaminated by the poisonous
drainage of a factory or the refuse resulting from certain mining
operations. In manufacturing districts it is not at all uncommon
to find a stream that is utilised as a motive power for working the
machinery of mills, and which also receives the waste products of
certain chemical operations, absolutely lifeless; but even here the
smaller streamlets that drain into the main course may be exceed-
ingly productive.

Probably, however, nothing will be gained by occupying space
in the discussion of such matters as these, or to attempt to lay down
any fixed rules for the collector’s guidance, for any one who exer-
cises his observant faculty to a moderate degree will soon become a
fair judge of the prospects before him.

And now, having reached the bank of a selected hunting ground,
how are our operations to be carried on ?

First, then, previous to the attack on the water itself, carefully
examine the surroundings. If your search is conducted during the
winter months, much may often be learnt by overturning stones
and logs of wood, for in this way you may meet with hibernating
amphibians and other creatures, and thus become acquainted with
their habits at a period during which they are generally neglected.
If it is summer time, then never omit an examination of the sur-
rounding foliage, also the surfaces of bare stones, and neighbouring
walls, fences, and trunks of trees.

If dragon flies are seen on the wing, get your light net ready
for action, and keep it handy by you throughout the hunt. Some
of these fly with marvellous rapidity, calling your utmost skill into
activity, while others are easily ‘bagged.’ During very dull weather
most of them remain at rest, generally very near the water’s edge,
and often on reeds and other aquatic plants that stand out above
the surface of the pond or stream. At such times the net is fre-

ON COLLECTING IN PONDS AND STREAMS 23

quently unnecessary, for the insects may be easily ‘ boxed,’ or even
removed from their hold by taking the wings gently between finger
and thumb.

On stones, walls, fences, and trunks of trees in the vicinity of
the water, more especially near the banks of running streams, we
may meet with other members of the order Newroptera—insects
commonly known as stone flies, alder flies, and willow flies. These
are,as a rule, very lazy creatures, and may generally be easily
taken in pill boxes as they sit. Glass-bottomed boxes are most
suitable for this purpose, for they enable you to see the insect after
it has been captured, and thus acquaint you with a favourable
opportunity of popping on the lid.

Having surveyed the surroundings of the pond or the banks of
the stream, examine the outstanding and floating weeds at the
water’s edge, and the herbage that overhangs the water from the
banks. Here you may meet with Succinea putris and other mol-
luses of the same genus, which, though not strictly aquatic, fre-
quent marshes and the banks of ponds and ditches; and, thus
coming frequently within the range of the pond-hunter’s observations,
may reasonably be included among the objects of his search.

Few spectacles are more interesting than the emergence of the
perfect insect from its pupal skin, and the collector at work on the
banks of ponds will sometimes catch sight of the pupa of a dragon
fly, walking up the stem of an aquatic plant in order to undergo
its final metamorphoses. Such a sight should never be missed if
the opportunity presents itself, and the temporary postponement of
your dipping, scraping, and dredging will be well repaid by the
instructive lesson afforded by a careful observation of the transfor-
mation.

Having thus learnt all you can by a close scrutiny of the water’s
edge and its vicinity, preparations must be made for the attack on
the pond itself; but even in this it is generally a bad policy to dash
straight off with the net. First watch the surface of the water and
its floating and partially submerged weeds, and catch what you
require of those creatures which live principally or entirely on the
surface, before the pond is disturbed to any great extent. Some of
the creatures to which we refer would either dart to the bottom or
scuttle away to the centre of the water beyond your reach if you
started with a bold attack ; and the water would soon be rendered
so muddy that all further observation of the living beings in their
haunts would be impossible. If you see any aquatic snails you

24 THE COLLECTOR'S WORK

require, resting on the weeds close to the surface, or crawling, as they
frequently do, in an inverted position along the surface film of the
water, place a very shallow net gently beneath them and lift them
out without disturbing the surroundings. Water gnats (Hydro-
dromica) and whirligig beetles (G@yrinid@)—of each of which there
are several species—may be seen sporting in the sun, and these
may be taken in the same way, but the net must be brought up
smartly against them from below.

Attention must next be given to the hitherto unseen inhabitants
of the water, but avoiding, for the present, those which make their
home at the bottom. Place the shallow net against submerged
plants, and scrape them upward to remove the water snails that
adhere to their leaves. If the herbage is very dense, substitute the
metal scraper for the ordinary ring-net. By this means you may
secure newts and univalve molluses, together with various larve,
such as those of the caddis flies, and also the aquatic caterpillars of
the china-mark moths (Hydrocampid@) which live in cases of their
own construction and feed close to the surface of the water.

Presently we shall learn what is to be done with the various
creatures captured—how they are to be conveyed home with the
ereatest convenience and with due regard to their safety.

Now we make our attack on the bed, and, if this is composed of
a soft mud, as is generally the case, we are obliged to abandon all
further attempts to keep the water clear and transparent. A deeper
net is chosen—one about nine inches or a foot in depth ; and, instead
of working the net upwards, we may force it well down on the
bottom, and scrape it in towards the bank. ‘The first haul will give
you some idea as to the force to be employed during this part of
your work. If the weeds are so dense that the bottom is not
reached at all, then a little more downward pressure must be
applied. If, on the other hand, the net is full of soft mud or too
heavily laden with sand or gravel, the pressure may be reduced.
However, it must be remembered that we are now searching for the
creatures that prefer the bottom, including those which live par-
tially or wholly buried in the bed, and that it is therefore absolutely
necessary to haul in more or less of the substance in which they
reside.

It often happens that the weeds are so dense in ponds and slug-
gish streams that there is no getting at the bottom with any other
than a very strong and rigid net; and, under these circumstances,
the dredging hook may prove useful in clearing away some of the

ON COLLECTING IN PONDS AND STREAMS 25

excess of vegetation, at the same time bringing abundance of animal
life within your reach.

While thus engaged in the search for the denizens of the deep,
you will of course land a quantity of weed together with the
creatures that lodge thereon; and this is the time when your hauls
will be richest, both as regards quantity and variety of species. So
marvellous, indeed, is the yield of some of our ponds and ditches,
that two or more persons might find constant employment for the
time being in the examination of the material landed and in the
selection and boxing of the creatures required.

Always turn out the contents of the net on a piece of bare ground
near the water, otherwise some of the most active creatures will
soon disappear among the grass.

Having first picked out as much clean weed as you require, and
placed this in the can, you may commence the process of selection.
As a rule nearly all the larger creatures may be dropped into the
can, where they will be pretty safely lodged till your return; and
no water, except the small quantity that drains from the wet weeds,
need be taken unless you are including fishes in your captures.
Nor will it be necessary to take much pains in the separation of the
carnivorous and the more helpless creatures, providing you have

large quantity of vegetation, and are not com-
“ii your captives in the collecting can for a lengthened

Small molluscs, and indeed all small creatures which you
specially value, either because they are rare or because they were
previously unknown to you, must be placed separately in small
boxes ; chip boxes being used for the molluscs and other creatures
that do well for a time without water, and small tins, each contain-
ing a little pond-weed, for others (chiefly the soft-bodied animals
that have no hardened covering) which must not be allowed to get
dry.

It frequently happens that aquatic plants harbour such a host of
small molluses and other little lodgers, that the examination and
selection occupy no small amount of time, and in this case, pro-
viding you have the accommodation at your disposal, it is a good plan
to pack a quantity of the weed into a separate can, and reserve the
more careful inspection for your leisure at home.

I have recommended the thorough examination of aquatic
plants, but it must not be forgotten that the mud, sand, or gravel
removed from the bottom should be searched with equal care. The

26 THE COLLECTOR'S WORK

first-named material is the home of numerous larvee of beetles and
other insects, and often contains small bivalve molluses (Spherida)
which would be overlooked by a careless observer; and the only
British species of the Neritina genus may often be found attached
to the surfaces of stones taken from a gravelly bed.

Although the preceding operations are quite sufficient for the
general success of the collector of animal life in fresh water, yet an
occasional hour or so with the dredge will be necessary, more
especially for the taking of the larger bivalve molluses (Unionidae)
and other inhabitants of large ponds and deep water.

In some cases a small boat is a great aid during the dredging
manipulations, but much may be done without its assistance. We
have already referred to forms of dredging nets which do not retain
their proper position well while in use, and which, if dropped into
deep water, may fall on the wrong side. With such dredges, and
indeed with any form of dredge, the following modus operandi will
succeed well whether for ponds of moderate size, the arms of lakes,
very large ponds, or even rivers, remembering that two persons can
do the work better than one :

Place the dredge on the bank close to and facing the water’s
edge. Tie a stone of suitable size to the end of a string. Throw
the stone to the opposite bank, and then haul the dredge across.
By this means you are enabled to work on ground otherwise beyond
your reach with the best possible chance of the dredge maintaining
its proper position. Should the dredge prove too light for the work,
as will probably be the case on a gravelly bottom or where there is
a superabundance of weeds, then it must be weighted as already
suggested.

During the summer months most ponds are so full of animal
life that you will generally land hundreds of creatures of the com-
moner species which you do not require ; and in the case of small
ponds especially, if your work as a searcher is well done, you will
have considerably reduced the density of the population by the
numerous haulings. Now, it is not right that all these harmless
creatures that add so much to the beauty, purity (for many of them
are very useful scavengers), and usefulness of our ponds should be
permanently removed from their element and left on the bank to
dry and perish in the sun; and for this reason every thoughtful
and humane collector of freshwater life does not mind the trouble
of pushing back into the pond the masses of weed and other matter
which still teem with life after he has removed all he requires for

ON COLLECTING IN PONDS AND STREAMS 27

his own study. The time spent in this act is trifling compared with
the good done and the satisfaction obtained, and the act itself soon
becomes so habitual that it is accomplished almost involuntarily,
so that the doer experiences no feeling of additional labour or any
loss of time.

It now remains for us to see what is to be done with all the
takings on our return home.

As arule the miscellaneous contents of the can should receive
the first attention, particularly so if it is overcrowded and contains
many voracious larve. Throw all into a large tub or bath contain-
ing water only two or three inches deep, for the selection and sort-
ing of the various creatures will be a matter of considerable time
and difficulty if they have an opportunity of hiding at a depth where
they are not easily seen.

The aquatic plants required for the aquaria may be set in posi-
tion at once, after having been examined for creatures which are
to have special lodgings consigned to them. Fishes, if any, should
generally have the most space. Water beetles and carnivorous
larve must have an apartment to themselves. Molluscs may be dis-
tributed among the various aquaria, large and small, but a special
glass jar may be reserved for any species which are to be favoured
with a special study. Freshwater shrimps are very useful as
scavengers, but do not do so well in still as in running water. And
so we arrange the specimens according to the accommodation at
our disposal: and the direction which our studies and observations
are to take.

The larger and more active creatures are best transferred by
means of a small net, about four or five inches deep, and this may

Fic. 29.—Wire Support ror THE AQuARIUM NET

be mounted on a single piece of galvanised iron wire bent as shown
in fig. 29, so. that it forms both ring and handle. Such a net is
always, useful as an accessory to the aquarium, not only for the
transference of living things, but also for the easy removal of the
dead.

But it will invariably be found that the contents of the collect-
ing can include a host of creatures that are much too small to be

28 THE COLLECTOR'S WORK

removed with a net. Such are the small larve and water beetles
little molluses—both univalve and bivalve—water fleas, cyclops
&e., to say nothing of the numerous truly microscopic beings.
These are easily removed and transferred to suitable quarters by
means of a dipping tube.

This exceedingly useful accessory is simply a straight piece of
glass tubing, of about three-sixteenths of an inch internal diameter,
and about nine inches long or more, according to the depth of the
vessels in which it is to be used. It is employed as follows:

Close the top of the tube firmly with the finger, and then plunge
its lower end into the water till it is immediately above the object
desired. Then remove
the finger, and the water
will suddenly rush up the
tube, carrying the object
with it. Close the top
again, and you may then
withdraw the tube with-
out losing any of its con-
tents, which may be
allowed to run out again
by admitting air at the
top. Even small molluscs
and other objects heavier
than water may be trans-
ferred in this way, but,

Fic. 30.—MrEtTHoD OF USING THE when dealing with these,
Direinc TuBE it will be necessary to
withdraw the tube before

they have had time to sink to the bottom again.

The dipping tube is also useful for removing drops of water for
examination under the microscope, but this is a matter for considera-
tion in our next chapter.

We have not yet referred to the specimens brought home in
small boxes. Most of these will probably be objects obtained from
the water, and may be replaced in their native element according to
the convenience or the desires of the collector; but they may often
include winged insects, such as caddis flies, stone flies, dragon flies,
&e. These may be turned out into any kind of vessel—a large
bell-jar, a propagating glass, a fern case, or even a conservatory——
where their movements may be watched while they live; and,

ON COLLECTING IN PONDS AND STREAMS 29

when dead, they may be set for a permanent collection according
to the instructions given in a subsequent chapter (Chapter IV).

Few collectors of pond and river life would contentedly neglect
the interesting study of the infinitely small, yet there may be many
who cannot afford the luxury of a really good compound microscope ;
so, in our endeavour to satisfy the demands of the majority of
beginners, we shall, in our next chapter, deal with the collection of
the minute forms of aquatic life, and the manipulation of an in-
expensive magnifier such as will probably come within the reach of
almost everybody.

50 THE COLLECTOR'S WORK

CHAPTER III

THE COLLECTING OF MINUTE FORMS OF LIFE.
THE USE OF THE MICROSCOPE

THE. methods of collecting and examining the lower and minute
forms of animal life are so different from those already described
for the larger species, that it is more convenient to deal with them
separately ; so we shall devote the present chapter exclusively to
this interesting portion of the pond-hunter’s work ; and, following
the plan of the preceding pages, we shall first enumerate and
describe the apparatus for the work in the field.

The ordinary pond net is, of course, absolutely useless in this
case, for the minute creatures required readily pass through the
meshes of the gauze; but a very small net, two or three inches in
diameter, and made of the finest muslin, is often useful for lifting
out small weeds to which many of the lower forms attach them-
selves.

Our chief work now consists in securing the numerous little
animals which move freely in the water, or which attach themselves
to small floating or submerged objects, and these are readily obtained
by simply taking samples of the water itself, together with the
small particles of matter that give a foothold to the less active
creatures.

This object is most conveniently attained by means of several
little bottles or tubes, fitted with corks. These can be easily
fixed in succession on the end of a stick.

Little tubular bottles, two or three inches long, are best suited
for the purpose. A spring clip, capable of holding them firmly, is
fastened on the end of a walking stick ; and by this means a suc-
cession of dips may be made in the various ponds and ditches
visited.

It mumay be asked, ‘ Why not put all the samples taken into one
large bottle instead of into a number of small ones?’ But it will be

COLLECTING MINUTE FORMS OF LIFE 51

readily seen that the isolation of the different samples taken will
enable us to compare the productiveness and peculiarities of the
different pieces of water examined, so that on future visits to the
saine neighbourhood we know just where to go for particular forms
of life. And in order to further assist us in becoming familiar with
the habitats of the more interesting forms, we should always place

vA
Tm iH

UM

Fic. 31.—Diprpinc Borrne anp Curie

a blank label on each bottle, so that the samples collected may be
marked with the nature of the piece of water from which they were
taken, together with any other memoranda of interest or im-
portance.

Although we are now dealing with what is generally spoken of
as microscopic life, yet it must be remembered that many of the
animals included under this head are distinctly visible to the naked
eye, and others are easily rendered visible by means of a pocket
magnifying lens. This being the case, we can often form some
rough estimate of the amount of life in any collected sample by a
cursory examination in the field; and to this end we include a
pocket magnifier in our outfit.

The well-known ‘ Coddington lens’ is a very convenient one for
this purpose. I have also found the focussing-glass serve extremely
well for the examination of the samples of water collected, when
combining the photographic study of natural objects with a little
pond-searching during the same outing,

It frequently happens that the contents of each bottle include
much less of animal life than we should like to transmit by it

32 THE COLLECTOR’S WORK

perhaps only a few visible forms of species of which we should like
a considerable stock for future experiment and observation. In
this case a small strainer is useful for the purpose of concentrating
a larger number of living things in a given quantity of water. |

The reader will probably

be sufficiently ingenious to

_ design and construct a simple
piece of apparatus for this
purpose from materials ready
at hand, but for the help of
those of aless inventive turn,
a figure and brief description
of one that has done good
service follows.

It consists of a wide-
mouthed bottle, fitted with
a good cork, through the
centre of which passes an
ordinary tin fuanel.. Two or
more large holes are bored in
the cork in addition to the
one which receives the funnel,
and these are all covered

Fic. 32.—Tux ‘Copprneron’ Lexgs below by means of a piece
of the finest muslin.

It will now be seen that if water be poured into the funnel
beyond the capacity of the bottle, the excess will pass through the
muslin and escape through the cork. Thus any quantity of water
may be strained, and the residue, rich in animal life, may then be
transferred to bottles or tubes of a convenient size for transmission
in the pocket.

Tneed hardly say that the very minute animals will pass readily
through the finest material obtainable. But a great variety of living
beings may be encompassed in a small space by means of the
strainer ; and a considerable number of the minutest forms even
may also be concentrated in the same way, for many of them
remain attached to pieces of weed and particles of miscellaneous
matter that will not pass through the holes in the muslin.

One other hint I should like to give betore closing our short
account of the few appliances required for this portion of the pond-
hunter’s work There are times when business or other circum-

COLLECTING OF MINUTE FORMS OF LIFE 33

stances prevent a run to the fields, when, at the same time, a few
odd moments now and again could be spared for the observation of
specimens previously collected. Then, to prevent disappointment in
this matter, why not have a pond—a col-
lecting ground teeming with all kinds of
microscopic animal life—at home ?

The establishment of such a ‘ stock’
is easy in the extreme. Take a dipping
bottle and stick, strainer, and bait-can.
Collect samples of water from every pond
and ditch you meet with. Pass all through
the strainer; and as often as the strainer
shows signs of a great density of popula-
tion, throw its contents into the bait-can.

In this way you soon obtain a quart
or so of water containing thousands of
living forms in every inch. Take this
home, throw it into any large vessel that
will answer the purposes of an aquarium,
and then dilute with clear water.

Here, then, is your pond. At any =
time, and in a manner to be presently F1¢.33.—THE Srrarver
described, you may remove a drop of water
for microscopic examination, or secure any particular little creature
you may observe with or without the aid of a lens.

In our chapter on the aquarium there are the necessary instruc-
tions for the aération of the water and the prevention of putrefaction ;
and if a little attention be paid to these matters your ‘ stock’ will
keep in good condition for a very long time; in fact, there is no
reason whatever why many of the animals should not continue their
successions of generations for years, with no trouble on the part of
the owner save the occasional addition of a little water to replace
that lost by evaporation.

While speaking of the requisites for field work, some hints were
given concerning their uses in the field; but we must now apply
ourselves particularly for a short time to the out-of-door operations.

Microscopic life is to be found in ponds and streams all the year
round. , On the coldest days of December and January, even when
ice covers the surface of the water, living beings are more or less
active. But the harvest time of the collector is undoubtedly the
summer months.

D

34 THE COLLECTORS WORK

As a rule the microscopist need not travel far in search of game.
Almost every permanent pond and ditch, however small, teems with
life; and even a few minutes spent in collecting the casual visitors
of the waterbutt will often yield specimens that may profitably be
studied for weeks. But occasionally it will be necessary to pay visits
to distant waters in order to collect certain specimens that are not
to be taken nearer home, for the microscopic as well as the higher
life includes local species, which thrive better on certain soils than
on others, or which are to be found exclusively or almost so on cer-
tain species of aquatic plants.

It will always be noticed, however, that certain pieces of water
are far more productive than others, even in the same immediate
neighbourhood; and the general outward appearance of the best
hunting grounds will soon become familiar to the worker.

Very little microscopic life is to be found in streams, more
especially the rapid ones. Very sluggish streams, particularly those
of small size, yield more. But ditches and ponds are literally full
of life, even to the narrowest and smallest puddles.

You take a dip from the water of each pool or ditch visited,
examine it carefully by holding it up to the light and looking into
it through the lens. If it shows signs of life—such life as you are
requiring—cork the bottle and place it in your pocket reserved for
the samples, with, of course, some provision for preventing the
bottles from clashing together and breaking.

Such samples as give only a little evidence of life, yet of a kind
required at the time, may be passed through the strainer as above
directed ; and little fragments of pond weeds and débris that find
their way into the dipping bottles and strainer should always be
retained for the examination and study of such specimens as may
be attached to them. It should also be known that many micro-
scopic animals live almost exclusively on or in the mud at the bottom
of ponds and ditches; hence it is necessary to take home some of
this sediment, which may generally be most conveniently scooped
up from the margins.

Should you happen to meet with a pond or ditch exceptionally
rich in microscopic life, and also happen to have your pond net and
can with you, by all means embrace the opportunity of laying in a
stock from which you can obtain interesting objects to occupy your
spare moments at home. In this case there will be no need to
burden yourself with any large quantity of water, but simply place
in the can several clumps of pond weeds, always including, when

COLLECTING OF MINUTE FORMS OF LIFE 35

possible, a good supply of duckweed. Myriads of little beings will
be hauled in with the vegetable matter thus secured, some attached
to the leaves, stems, and rootlets, and others free in the water that
adheres to the entangled masses of weeds. To this, of course, may
be added any samples of water which show abundant signs of
animal life.

As soon as possible after your return you must give some atten-
tion to the takings. The corks of the bottles or tubes should be
removed at once, in order that the little animals may not be killed
through a deficiency of air. Then set before you a number of glass
jars, and throw into them the contents of the bottles, isolating the
takings from each separate pond or ditch as far as you think de-
sirable. Add some ordinary water to each of the samples, and then
put into each jar a little of any kind of pond weed. The weed will
aérate the water, and thus keep the contents of the jars in good ¢on-
dition for a considerable time.

Then, as regards the contents of the can, throw them all out
into any large vessel—jar, pan, or any other suitable receptacle, add
plenty of water, and then set it aside in a cool place out of the way of
the direct rays of the sun.

There is much to interest one in the movements of some of the
larger of the so-called microscopic creatures, even when viewed
without the assistance of any kind of magnifier; but the details of
these movements, as well as the structure and development of the
minute beings, are not to be observed without the aid of a micro-
scope; and since this instrument is absolutely indispensable to
any one who intends to study the lower forms of aquatic life, we shall
now deal briefly with the methods of using it as far as they are
likely to be of service to beginners in this department of natural
history.

Microscopes are of two kinds—simple and compound. The
simple microscope is merely a magnifying lens or a combination of
lenses mounted on some kind of support. It is, in fact, merely a
magnifying lens such as we have recommended for field work, with
the addition of a stage on which to place the objects that are to be
examined, and perhaps also a mirror by means of which light may
be reflected through transparent objects.

One of the best forms of this instrument is represented in fig. 34,
in which the eyepiece, m, carrying the convex lens, is fixed on a
horizontal support, E. The stage, b, is perforated at its centre, so

D2

36 THE COLLECTOR’S WORK

that light reflected upwards by the mirror, M, may be made to pass
through transparent objects supported on it; and the distance
between the lens and the object may be adjusted by means of the
rackwork, K, and the screw, D.

A great number of very interesting movements and structures

that are not to be observed w‘th the unaided eye, may be witnessed

hrough the simple microscope;
but this instrument, although
useful at times even to an ad-
vanced student of microscopic
life, is of no use in the study of
the more minute forms.

It is absolutely essential,
therefore, that those who intend
to make microscopic life a study
should have a compound micro-
scope that will magnify to at
least three or four hundred dia-
meters.

I do not want to discourage
beginners by counting over the
cost of such an instrument as

Fic. 34.—A Smite Mricroscorr I would recommend; but I

must say at once that a really

useful microscope for general work cannot be obtained under four
or five pounds.

It is well to remember, however, that the amount of work that
can be done is about proportional to the quality of the instrument
used—that a little may be done with the aid of a really cheap
instrument, more still with a better one, and the most advanced
work with the best appliances. This being the case, there is no
reason whatever why the young student of pond life should not at
first secure the best instrument and accessories which his funds
permit, and then settle down cheerfully to do the best work he
can with whatever he is fortunate enough to secure.

When a youngster, I myself found that much pleasure and
profit could be obtained by the use of a little microscope similar to
that figured on page 37, and which cost only about fifteen shillings.
It had only one eyepiece ; and the three lenses, called the objec-
tives, fitted at the bottom of the tube, could be used singly or
combined, thus giving the different ‘ powers’ required for different

COLLECTING OF MINUTE FORMS OF LIFE 37

classes of objects. It had also a reflector—a rotating mirror
beneath the stage, by means of which the light could be re-
flected upwards. Such microscopes are readily obtained; and,
although far behind the requirements of the student, are certainly
preferable to no microscope at all.

More useful instruments are sold
under such names as ‘ The Student’s
Microscope,’ ‘ The College Microscope,’
‘The School Microscope,’ &c.; gene-
rally ranging in price from about fifty
shillings to twice that sum. The price
includes one, and sometimes two eye-
pieces ; also two objectives, and often
one or two minor accessories.

The purchaser of a microscope is
often allowed a choice of objectives,
and this is certainly a great conveni-
ence, for the powers suitable for the
work of certain persons might not be
at all adapted to that of others. The
most useful objectives for the study
of pond life are the 2-inch, 1-inch,
$-inch, and }-inch; and, where the
purchaser is limited to two, preference
should be given to the 1-inch and the
+-inch.

These objectives or object glasses
are named according to their focal
distances, and those of longer focus
have the lowest magnifying power.

It is not possible to give here the oS tt ae i a
magnifying powers of the different Gowrounp. MICROSCOPE
lenses, for they will vary with the in-
strument and the manner in which it is used; but it will be seen
that, with two eyepieces and two objectives, four combinations,
and hence four different powers,can be employed. Again, an in-
crease in magnifying power can also be made by drawing out the
sliding tube of the microscope without making any change in the
lenses; but the increase in the dimensions of the image brought
about by this means is generally obtained at a considerable
expense as far as clearness of definition is concerned.

’ STUDENT'S Microscopr

COLLECTING OF MINUTE FORMS OF LIFE 39

A ‘condenser’ is often supplied with a good compound micro-
scope, sometimes fixed, and sometimes supported on a separate
adjustable stand. It is a convex lens of short focus, the use of
which is to converge the light passing through it so that it may be
concentrated on a small object.

It may be placed between the reflector and the object on the
stage, so that a very powerful light may be sent through the
latter ; or it may be used to concentrate the rays of light from a
higher level down on to the top of an opaque object. But it is not
likely to be of very much service used in either of these ways, for
the light thrown up by the mirror is usually quite strong enough
for transparent objects, and the pond-hunter has but little to do
with opaque ones.

Nevertheless the reader should procure one of these lenses, for
he can easily convert it into what is known as a‘ spot lens’ for the
examination of transparent objects over a black background. To
do this, cut out a piece of black paper just large enough to cover

Fic. 37.—SEcTION OF THE Spot LENS

the flat side of the lens, and then from the middle of this a
circle, three-quarters of an inch in diameter, being careful to have
a clean edge. Gum this on the flat side of the condenser, and then
fix a circular piece of the same paper, half an inch in diameter, in
the middle of the clear space left, thus leaving only a ring of the
glass an eighth of an inch wide, uncovered.

If this lens is now placed between the reflector and the stage,
and at a suitable distance from the transparent object to be
examined, light thrown on it from below will be converged on
the object through the clear ring of glass, while the black back-
ground, formed by the central black spot behind it, will enable the
details of structure to be seen distinctly.

We have-now to consider the several little appliances required
in conjunction with the microscope. These are glass slips, cover
glasses, cells, live-box, zoophyte trough, watch glasses, glass jars,
dipping tubes, forceps, scissors, needles, scalpels, Ke.

The glass slips generally employed measure three inches long

40 THE COLLECTOR'S WORK

and one wide, and are ground at the edges; and the cover glasses
are very thin circular or square pieces of various sizes.

Unless the reader intends to mount permanent specimens for the
microscope, he will find about a dozen glass slips quite sufficient for

his purpose. And, as regards
the cover glasses, a quarter of
an ounce of circles, mixed sizes,
will answer all requirements for
some time.

The cells are simply rings of
some suitable material, of the
same size as the cover glasses, cemented to the slip. A cell is
necessary when the cover glass has to be raised in order to avoid
pressure on a small object, or to give sufficient space between the
two glasses to accommodate an object of larger size.

Microscopists generally make their own cells, either by cement-
ing rings of glass, ivory, ebonite, or other material on the slips; or,
when a very shallow cell is required, by placing the slip on a turn-
table, and making a ring of a quick-drying cement. The rings used
can be purchased; but perhaps it is better for a beginner to buy a
few cells of different diameters and varying depths ready made.

A live-box is often supplied with the microscope. This and the
zoophyte trough are really cells of a larger size, suitable for
the observation of the movements and development of living
objects.

Watch glasses are exceedingly convenient for the isolation and
preliminary observation of small quantities of pond water. They
may be bought at the rate of about sixpence a dozen.

Almost any kind of glass jar may be used to contain specimens
of water in which the microscopic animals are to be stored, but the
best for the purpose are those which are flanged at the top and
have ground edges. Ground glass discs are also useful as covers to
keep out the dust.

The simplest form of dipping tube is merely a piece of glass
tubing, of about a quarter of an inch internal diameter, eight or
nine inches long, with the edges smoothed; but it is convenient to
have at least one tapered off at one end. They are easily made as
follows:

Procure a three-foot length of glass tubing of the size named,
and cut it into three pieces, one eighteen inches and two nine inches
long. To cut the tubing, give a sharp stroke with a small triangular

Fic. 38.—CrLt on Guass Siie

COLLECTING OF MINUTE FORMS OF LIFE 41

file, and then pull the two parts asunder, slightly bending the tube
from the side of the file-cut.

Let the ends of the two nine-inch pieces just touch the outside
of a gas flame for a few seconds, and the edges will be softened by
the heat, and become perfectly smooth. Thus two plain dipping
tubes are completed.

Now take the eighteen-inch length, and heat it in an ordinary
gas flame, holding it the broad way of the flame, and turning it
round and round that it may become equally heated on all sides.

Fic. 39.._SHOWING HOW TO SOFTEN GuLass TUBING

When it is so soft that it easily bends by its own weight, take it out
of the flame, and pull the two halves very slowly in a perfectly
straight line till the diameter in.the smallest part is reduced to
about one-half or rather less. Continue to hold it in this position
till the glass has become rigid, and then set it aside to cool.

When cold, cut the tube into two where the diameter is smallest,
and then cut one piece at a point where the diameter is inter-
mediate between the largest and the smallest. Thus two dipping

SS

Fic. 40.—SHOWING WHERE TO CUT THE TUBE IN ORDER TO GET
two Diprinc TUBES WITH DIFFERENT APERTURES

tubes are obtained, with their smaller ends of different sizes. Both
small and large ends should now be smoothed in the gas flame as
recommended for the straight tubes.

The forceps, we need hardly say, are used to pick up and to hold
very small objects. The needles answer the same purpose, and
these are so frequently of service, and so inexpensive withal, that
the young microscopist should never be without them. They

42 THE COLLECTOR'S WORK

should always be mounted in small wooden handles, which can
be readily done by pushing the eyes into little pieces of twig ; and
one or two might, with advantage, have their points bent, while
others may be ground on a hone till their points are flat and sharp.

The scissors should be very pointed, and must cut well quite to
the point. If the reader desires to have the best appliances in this
respect, he had better purchase two pairs of small dissecting scissors

—one with straight and the other with bent blades.

The other item mentioned in our list is the scalpels or dissecting
knives. The well-sharpened blades of an ordinary pocket knife
may be made to answer all the purposes of these; still, where much
practical work is anticipated, it will be as well to procure a case
of scalpels, and such cases generally contain, in addition to the
knives, a pair of forceps and one or two pairs of dissecting scissors.

Before commencing the examination of the collected specimens
of pond life, always make it a rule to have every appliance that may
posstbly be required ready at hand. Then, by means of a dipping
tube, small quantities of water may be removed from the jars or
bottles, and little objects visible to the naked eye or with the aid of
a lens may be selected and transferred.

If it is simply desired to remove a drop or so of the water,
immerse the dipping tube into the jar, and then close the upper end
with the forefinger and withdraw it. As long as the top of the
tube is closed so firmly that air cannot enter, the water will not flow
out; but if the pressure of the finger be very gradually released,
the water will sink so slowly that single drops and even smaller
quantities may be transferred to glass slips for examination.

Sometimes it may be required to isolate a portion of the water
and sediment at the bottom of a jar, or to remove some one
particular animal that is seen swimming about in it. To do this,
close the top of the dipping tube firmly, previous to plunging it into
the water, and when the lower end is exactly over and close to the
thing wanted, open the top of the tube, and the water will imme-
diately rush into it, carrying with it just what you require. When
dealing with very small objects, and in other cases where it is
advisable to withdraw and transfer only very small quantities of the
water, one of the dipping tubes with reduced apertures should be
used.

A careful observer will soon discover that very interesting and
instructive movements of aquatic animals may be watched with
the aid of a hand lens as the creatures swim about in the glass jars,

COLLECTING OF MINUTE FORMS OF LIFE 4838

or as they creep over the glass itself. But it is often impossible to
follow the little animals as they move rapidly about in the liberal
space provided them, so we secure them in a dipping tube and
transfer them to a watch glass or into the zoophyte trough, where
they are more conveniently watched either with a hand lens or
under the low powers of the compound microscope.

The very small animals, including those which are quite in-
visible to the unaided eye, are to be removed in a drop of water by
means of a dipping tube in the same way, and then transferred to
the middle of a glass slip. A cover glass of convenient size is then
placed gently on the top of it. First one side is made to rest on the
slip, and then the opposite edge, held by a pair of forceps or
supported on the point of a knife, is gradually lowered on to the
water so as to avoid air bubbles.

In many cases a drop of moderately clear water is full of life,
but all the animals are so very small that they move with perfect
freedom in the thin film of water between the two glasses, which
appear to be in absolute contact. But no pressure must be applied
to the cover glass, or the little animals, which generally resemble
a small mass of almost transparent jelly, will be crushed and
destroyed. .

Sometimes, however, objects of a somewhat larger size are to be
examined, and it is often necessary at such times to relieve them
from the pressure, small though it is, of the cover glass. This is
easily done by supporting the glass on two or three little fragments
of weed, or by using a shallow cell.

Whether a cell is used or not it is always advisable to cover the
objects under observation. This prevents the loss of water by
evaporation, and so allows a considerable time during which the
development and progress of the specimens may be watched at
intervals.

The fronds of duckweeds and the leaves of various aquatic plants
often well repay the time spent in examination. Freshwater
polypes and fixed infusorians may often be found attached to them.
In dealing with these a shallow cell should be used, one just deep
enough to contain the piece of weed without pressure.

I will now make a few observations concerning the general
management of the microscope, assuming that the reader is pro-
vided with an inexpensive compound instrument like that we have
figured, and that as yet he is totally ignorant of the manner in
which it should be used.

44 THE COLLECTOR'S WORK

In the first place it is necessary to arrange for the illumination.
If it is day, all you have to do is to take a seat where you are facing
a window, and arrange your microscope and appliances before you.
But by night some kind of artificial light must be used.

For some purposes an ordinary gaslight at a little distance from
the operator is good enough; but gaslights flicker considerably as
a rule, and, at a distance, they
become not only feeble illumi-
nants, but the light thrown on
the slip by the reflector below
does not always cover the field
of observation when low powers
are used.

Therefore a portable lamp is
strongly to be recommended.
Microscopists’ lamps are to be
obtained at all opticians, but any
small and cheap petroleum lamp
may easily be converted into a.
really good substitute. Procure
a cylindrical tin box large
enough to cover the glass of the
lamp you intend to use. Knock
out its bottom, thus obtaining a
tin cylinder open at both ends.
Cut out from this a piece of
horseshoe shape as shown in
the illustration, and then sup-
port the shade on three wires
=—_S=S=S==> fastened to the brasswork just

Fic. 41.—Lamp wirn SHapE below the level of the flame.

The advantage of such a
shade is obvious. It allows the direct rays to fall on the reflector
of the microscope, at the same time shutting off the extraneous
light that might otherwise dazzle the eyes of the observer and
render the image indistinct. The back inner surface of the shade
also acts as a reflector, and directs additional rays towards the
instrument.

Having put the microscope in a convenient position with regard
to the illuminant to be used, move the reflector beneath the stage

' |
Ho

COLLECTING OF MINUTE FORMS OF LIFE 45

till the light is directed centrally through the aperture of the
diaphragm above it.

The remainder of the preparations depend on the nature of the
object to be examined. Let us suppose that it is required to
examine a drop of stagnant water, with the purpose, first of all, of
finding out what forms of life are present, and afterwards of looking
more minutely into the movements and structures of particular
species.

A drop of the water is first placed on the middle of a clean glass
slip by means of the dipping tube in the manner already described.
This must then be spread out into a uniformly thin sheet of water
by means of a thin cover glass, which will further serve to prevent
loss by evaporation.

The best way to apply the cover glass is as follows: Take up
the cover glass by means of a pair of forceps, and apply it obliquely
to the slip till it is over the drop, with its lower edge resting on the
slip ; then lower it gently on the water. A small strip of blotting-
paper should then be wiped carefully round the circumference to
absorb any water that may extend beyond the cover glass.

The examination should always be commenced with a low
power—a two-inch or an inch objective being used; for although
this may not enable you to make out the details of the smallest of
the living beings, it gives a wider field of view, and therefore better
enables you to get a general idea of the contents of the liquid. It
will also allow you to follow the movements of those active little
creatures which could not be kept within the limited field of a high
power.

Focussing, with a low power, is a matter of no difficulty at all;
but it is always advisable to start by racking or sliding down the
tube till the objective is too near to the object before the observa-
tion commences, and then raising it as you look through the instru-
ment till the correct distance is obtained. Thus, supposing you are
using a one-inch objective, bring the objective to about half an inch
of the object, and then raise the tube till you get the correct focal
distance. ‘

If this precaution is not borne in mind, there is always a danger
of racking the objective down on to the stage, thus crushing the
object to be examined and breaking the cover glass, for it is im-
possible to judge of the distance between objective and object as you
look down the tube of the microscope.

Most compound microscopes are provided with two racks for

46 THE COLLECTOR'S WORK

sliding the tube; one, called the coarse adjustment, by which the
tube can be quickly changed in position; and the other—the fine
adjustment, worked by a screw of a very fine thread, by which very
slight movements of the tube may be produced with ease.

It is now desired, we will suppose, to view a certain object with
a higher power, either in order that its movements may be watched,
or to become acquainted with the details of its structure.

First move the slip till the selected object is exactly in the
centre of the field, and then change the objective (and the eyepiece
too, if required), as quickly as possible if the creature is moving
freely about.

It is now necessary to bring the objective very near the object,
and in this case much greater care is required than with the low
power. Rack the tube down till the object glass almost touches
the cover glass, and then, while looking down, through the instru-
ment, rack it up very slowly, till the required details are revealed
by a sharp image.

Considerable difficulty will often be experienced when observing
very active aquatic creatures under a high power, as they are con-
tinually darting out of the field. If the movements of such are to
be studied, they must have a more limited space than that provided
by placing an ordinary cover glass on the slip. A very small
quantity of water should be used for examination—only a small
fraction of a drop, deposited from a pointed dipping tube, and that
should be covered by a cover glass of the smallest size. A very
gentle pressure may also be applied to the cover glass with a view
to the reduction of the thickness of the film of water beneath it,
thus limiting the movements of the creatures under examination.

The use of the spot lens has already been described. It may be
called into requisition in all instances where the object is colourless
and so extremely transparent that its structures are hardly distin-
guishable with an illuminated background.

In dealing with larger objects, such as the larve of aquatic
insects and the earlier stages of frogs, toads, and newts, a cell of
some kind must be used, the diameter and depth being adapted to
the dimensions of the objects themselves. The majority of these
aquatic creatures will live for a considerable time in a small
quantity of water under a glass cover, and thus give us very
favourable opportunities of watching all movements in connection
with respiration, digestion, and circulation, as well as those of loco-
motion.

COLLECTING OF MINUTE FORMS OF LIFE 47

Thus, many are so transparent that the processes of digestion
may be observed within the digestive tube. Contractile blood-
vessels, serving the purpose of hearts, may also be seen at work,
propelling the vital fluid through the smaller tubes. And, in the
case of tadpoles, the blood-corpuscles may be distinctly seen edging
their way through the narrow capillaries of the tail-fringe, while a
strong current of blood may also be observed rushing through the
main vessels in the middle of the tail.

To get a general idea of the character of such movements as
these a low power should be used, for with such the illumination
is better, the field larger, and the main structures more clearly
defined ; and the higher powers be used, as already directed, merely
for the observation of details within a very restricted area.

A pond-hunter seldom finds it necessary to examine opaque
objects, but as occasions for such observations do sometimes occur,
we shall conclude this chapter with a word or two on this subject.

The opaque object is placed on a dead black background, such
as may be provided by a strip of unglazed black paper. It is well
to have suitable backgrounds always ready at hand, and these can
be made by pasting strips of suitable paper on one or two of the
ordinary glass slips or pieces of stout card of the same size. A few
shallow cells, covered at the bottom with the same kind of paper,
are also convenient for hard and dry objects that might otherwise
easily roll off the slip.

The condenser must now be placed in a direct line between the
light and the object, the former being elevated so that it can shine
obliquely downward on the top of the latter; and the condenser
being placed so that a ray from the centre of the light to the object
traverses the centre of the condenser and strikes it at right angles.
The distance at which the condenser must be placed in order to
concentrate the most powerful light on the object can then be easily
found by moving it gradually to or from the stage, keeping it still
at right angles to the central ray.

48 THE COLLECTORS WORK

CHAPTER IV

THE POND-HUNTER’S MUSHEUM—PRESERVATION
OF NATURAL OBJECTS

Sooner or later the student of any branch of natural history ex-
periences a growing desire to gather round him a permanent collec-
tion of the objects of his study, not that he prefers the shrivelled
and sodden specimens of a museum to the living and moving
creatures of the field, nor with a view to the decoration of the apart-
ment in which he spends the greater part of his time, but to enable
him to observe and study the structure of those animals which could
not have been conveniently examined while alive.

But it is not only for this purpose that such collections are made,
for the various specimens form a valuable work of reference, to
which the owner can at any time have recourse for a more mature
study of things collected years before—things which, when first ac-
quired, were imperfectly known, and of which the relationships and
position in the animal kingdom were not understood; but which
have since become more familiar, so that their correct positions in
the scale of life need no longer be matters of doubt.

Thus the owner of a museum—even of a modest one such as any
beginner could establish—is always surrounded by things which recall
happy memories of pleasant outings ; by well-known objects as well
as by things which he has a desire to know better; by a number of
forms, of which the study of the structure and relationships is too
interesting to be neglected.

The collection, also, is not a source of joy and profit to the owner
only, for where will you find a true naturalist who has not a desire
to stir up an interest in his pet study in the minds of his friends and
others, and what better means to this end could he possibly have
than a collection of natural objects, well preserved and arranged, by
which he can at any time illustrate his remarks on the beings that
have been such a source of pleasure and profit to himself ?

THE POND-HUNTER’S MUSEUM 49

In dealing with this branch of the pond-hunter’s work we shall
first consider the different methods by which the various forms of
life are to be preserved, and then append a few remarks concerning
the arrangement and labelling of specimens.

Microscopic Life

Many of the very small and delicate soft-bodied creatures of our
ponds cannot be satisfactorily preserved by any method, and con-
sequently they must always be studied while living or in a fresh
condition. Such of course do not find a place in any permanent
collection. They should, however, always be represented wherever
an attempt is made to display the creatures of the division to which
they belong.

The pencil and sketch-book are to be looked upon as valuable
aids to both microscopic and naked-eye observations, and drawings
should always be made of at least those creatures which cannot be
easily preserved. Such drawings, together with labels containing
the information acquired during the examination, may then repre-
sent the creatures from which they were taken.

Some really small objects, such as water fleas and cyclopes, can
be preserved in fluid, though of course they must always be studied
with the aid of a magnifier; but the only satisfactory method of
preserving many of the larger delicate objects and the majority of
the smaller ones, is to mount them as permanent microscopic
objects.

This work, however, cannot be taken up here. The different
methods of mounting objects for the microscope form a subject so
extensive that those readers who desire to master it are advised to
procure one of the manuals devoted entirely to it.

Preservation in Alcohol

We will now consider those animals which can be satisfac-
torily preserved only in a liquid. These include the soft-bodied
larve and the pup of many aquatic insects, worms and leeches,
water spiders, small crustaceans, all the stages of frogs, toads, and
newts, small fishes, and the eggs of various creatures.

Alcohol is by far the best liquid preservative for general use,
though turpentine and a few other liquids may be used with advan-
tage in certain special cases.

Alcohol is sold in several different qualities. Pure alcohol, quite
free from water, is known in the trade as ‘ absolute alcohol.’ ‘There

K

50 THE COLLECTOR'S WORK

is a heavy duty on it, and consequently it is rather expensive, the
usual price being three shillings and sixpence a pound. But it need
never be used pure; in fact, we shall see presently that it must of
necessity be considerably diluted with water in most instances.

Methylated alcohol, more commonly known as methylated spirit,
contains a certain amount of water, and is further adulterated by
the addition of wood spirit and mineral naphtha. The object of
this adulteration is to make it so unpalatable that it cannot be used
for making up intoxicating beverages, while, at the same time, its
use as a solvent of gums in the manufacture of varnishes and
polishes is not in any way interfered with. Being thus adapted
for the purposes of the trades and manufactures only, it is sold free
from duty, and costs only about four shillings a gallon. It is, how-
ever, much too strong for general use as a preservative of soft-
bodied animals, and possesses the disadvantage that it cannot be
diluted without the formation of a white precipitate which renders
it turbid and almost opaque.

The older methylated spirit, which is free from the mineral
ingredient, does not produce this precipitate when diluted, but there
is generally considerable difficulty in procuring it now free from
duty. It is known in the excise as ‘ ordinary ’ or ‘ non-mineralised ’
spirit.

If the last-named cannot be obtained, it will be necessary to get
the unadulterated alcohol, and dilute it as required for use accord-
ing to the nature of the objects to be preserved.

One of the most striking properties of alcohol is its powerful
affinity for water; and, as a result of this, the water contained in
soft animal structures immersed in it is extracted to such an extent
that they are shrivelled up till they are often quite beyond recogni-
tion. Hence the necessity of well diluting the spirit, and thus
satisfying this affinity for water, before any soft structures are placed
in it.

It must be remembered, too, that the diluted alcohol is quite as
good as a preservative. A fifty per cent. solution is strong enough
for any purpose, and even when brought down to twenty per cent.
it will prevent decomposition indefinitely, providing it is kept in
well-stoppered vessels.

If aquarium accommodation is very limited the collector cannot
do better than to take a bottle of diluted alcohol when out on a
pond-hunting expedition. Any soft-bodied animals captured may
then be dropped into the preservative and killed at once if there is

THE POND-HUNTER’S MUSEUM 51

no possibility of keeping them alive, and the bottle stocked in this
way will always afford abundant material for work during leisure
hours at home. At convenient intervals, too, the contents of the
stock bottle may be transferred to smaller tubes or bottles, properly
labelled, and made to occupy their respective places in the perma-
nent collection.

Among the interesting and instructive objects that may be
preserved in alcohol, we may particularly mention series of
specimens illustrating the metamorphoses of aquatic insects and
the batrachians. Thus, if some frog’s eggs be procured in the
spring, there will be no difficulty whatever in bottling a complete
series of specimens showing all the changes which the animal
undergoes, including several stages in the history of the egg itself.

The one thing to be remembered in connection with spirit as
a preservative is this: if the specimen becomes shrivelled the
solution of alcohol is too strong. There is no cure by which the
distorted objects may be restored to their proper shape ; but, know-
ing the cause of the failure, prevention, which is better than cure,
will be easy in future attempts.

Turpentine is often recommended as a preservative for spiders
and other creatures. This of course will not be diluted, as it has
not any aftinity for water as alcohol has, nor does it dissolve in
water.

The only advantage of turpentine over alcohol seems to be that
in certain cases the natural colours of the objects are better
retained.

After an animal of moderate size, such as a frog, small fish, or
large larva, has been in spirit for a time the spirit becomes dis-
coloured, and a deposit of extracted matter is often formed on the
_ bottom of the vessel. In this case the liquid with its sediment
should be poured off, and replaced by a fresh portion of spirit.

The discoloured spirit need not be wasted. If poured into a
large stock bottle it may be used over and over again as a pre-
liminary bath for similar specimens, which will in turn be trans-
ferred to a fresh preservative after they have apparently ceased to
colour the liquid and produce a sediment. ‘The ‘stock’ spirit may
be decanted carefully so as to leave all sediment behind, or it may
be filtered as occasion requires.

When specimens are preserved in a dry state, it is usual to set
them in some natural attitude before drying, or to arrange their
appendages in such a manner as to display as much as possible of

E 2

52 THE COLLECTOR'S WORK

the structure. This may also be carried out in the case of
specimens preserved in fluid.

If the latter are simply dropped into a bottle of spirit, not only
do they generally lie in a position in which they are not easily
observable, but the appendages often become unnaturally doubled
or contorted. The spirit, too, is a hardening as well as a preserva-
tive fluid, and therefore it is not generally an easy matter to ‘ set’
specimens that have been immersed in it for some time.

Very small objects may generally be well displayed in tubes or
bottles by simply suspending them from the cork or stopper by

TTT LI

Fic. 42..-A wipe SPECIMEN JAR Fic. 43.—A NARROW SPECIMEN JAR

means of a fine silk thread; but larger objects, the parts of which
it is required to arrange in some definite manner, may be mounted
as follows :

Cut a sheet of thin and clear mica as large as the specimen jar
will hold. Place the specimen or specimens on this, lay out the
parts as desired, and then hold them in position by means of little
loops of silk, brought through the mica with a fine needle, and tied
behind. When placed in spirit, a specimen so mounted may be
made to occupy the middle of the jar with, to all appearance, no
support whatever; for the mica becomes invisible in the spirit, and
threads of fine silk are hardly discernible.

Before closing our remarks about the wet method of preserving
animal specimens we will give a few hints concerning specimen

ss

THE POND-HUNTER’S MUSEUM 53

jars and tubes. The stoppered jars made especially for museum
specimens, and commonly known as anatomical jars, are rather
expensive, and even a small collection could not be put up in such
jars without a very considerable outlay. These jars, however, are
not at all necessary, for a very useful and even sightly collection
may be formed by the aid of the common wide-mouthed bottles,
fitted with good sound corks, providing there is uniformity of
pattern. The most useful sizes for a pond-hunter’s museum are
4 0z., 4 0z., 1 0z., 20z., and 4 oz., and the smallest of these will be
in the greatest demand. The prices of the bottles range from
about sevenpence to a shilling a dozen.

Specimen tubes, about two inches long and half an inch in
diameter, form the best accommodation for the smallest objects.
These may also be fitted with good corks, and arranged in boxes or
cabinet drawers in a manner to be presently described.

Preservation of Insects

We must next see what can be done with creatures of a drier
nature and harder texture, such as the dragon flies, stone flies,
caddis flies, and the beetles, flies, and moths that spend their earlier
stages in the water.

We have already recommended that these be captured with a net
if on the wing or if of a very active disposition, and taken in glass-
bottomed pill boxes if at rest and less wary. Those caught in the
net are transferred to pill boxes, and thus all are taken home alive.

The sooner these are attended to the better, for if allowed to
remain in their closely confined quarters for any great length of
time, it is probable that many of them will have damaged them-
selves in their struggles to escape.

They must first be killed—of course I am now speaking of those
insects which are not to be kept alive for observation or for breed-
ing—and then they have to be set out to dry for the museum
collection.

There are several points to be considered even when deciding
as to how the insects are to be killed. In the first instance the
method employed should be as speedy as possible, not only on the
score of mercy, but also because a prolonged fluttering is sure to
cause more or less damage to the appearance of the creatures which
are to be preserved.

Then, again, the insecticide used should always leave the joints
of the dead insects in a supple condition, so that the appendages

54 THE COLLECTOR’S WORK

v

can afterwards be put into any desired position without any danger
of snapping them off. Lastly, no agent should be employed that is
liable to permanently change the natural colours of the specimens.

One of the most convenient pieces of killing apparatus for
general use is the ‘cyanide bottle ’—a bottle containing a very
poisonous substance called potassium cyanide,
mixed or held in position by means of plaster
of Paris. Such a bottle may be purchased
for a shilling; and, if fitted with a good
sound cork, will retain its power for a long
time.

As with most other pieces of the natural-
ist’s apparatus, the cyanide bottle is much
cheaper when made at home, and the only
difficulty in the way of making one’s own is
the occasional hesitancy on the part of the
chemist to supply the cyanide to unknown
and, more especially, to young customers.
But it is well that such deadly poisons as
this cannot be obtained without some little
proof of the purchaser’s harmlessness, at
least to his fellow-creatures. There is another
and still greater advantage in knowing how to make the cyanide
bottle, for, with a small stock of cyanide always ready in case of
an emergency, a new killing apparatus can be made in two or three
minutes to replace one broken, and perhaps at a time when an
hour or two at least would be spent in journeying to the nearest
naturalist’s stores, or a day or two would pass before one could be
obtained through the post.

The modus operandi, then, is as follows: Procure a clear glass
bottle, large enough to contain the largest insect you are likely to
catch ; and, at the same time, of such a size as to be conveniently
carried in the pocket or satchel. Put a few small pieces of the
cyanide in the bottle—about a quarter of an ounce in all. Now
pour about a tablespoonful of water into a small basin or cup, and
sprinkle plaster of Paris into it, stirring it all the time, till the
mixture begins to set. Then put the plaster on the top of the
cyanide, and press it down even with the flat end of a round ruler.
Further, do not consider your work complete till basin, stirrer, and
ruler have all been well cleared of every trace of the poison.

There is another good way of making a cyanide bottle.

Fic. 44.— THE
CyANIDE BorrTie

THE POND-HUNTER’S MUSEUM 55

Instead of putting the solid cyanide into the bottle, dissolve it in
water, using as little of the latter as possible, and then mix the
solution with the plaster, and press it down flat, as_ before
mentioned.

The cyanide bottle is generally an instantaneous killer, but it
has one disadvantage, for it renders the joints of insects so
brittle that they cannot be set immediately after. If kept in the
bottle they gradually relax after a day or two, but then this is
not always convenient, especially in the case of an active collector,
whose bottle is in almost constant demand. We shall shortly
refer to another method by which insects may be relaxed, but
it would certainly be far better to employ some means by which
they may be killed without causing a rigidity such as the cyanide
produces.

Such a means is available in the form of the old-fashioned laurel
box, in which the insects are speedily killed by the vapours arising
from bruised laurel leaves.

A good laurel box may be easily made by procuring two cylindri-
cal tins of exactly the same size, knocking out the bottom of one,
and putting in its place the lid of the other. The
box, with a lid at each end, is then provided with a
perforated partition of wood or metal, firmly kept
in its place by means of a few small brads or a
little solder. One compartment is then packed
with well-pounded laurel leaves, while the other is
reserved for the reception of the insects.

The creatures killed by this apparatus always
remain so supple that they may be set at the
collector’s convenience; and, by the way, the
same box may be used as a relaxer for those insects
which have become rigid through the effects of »,, 45 Vu
cyanide, or which have been allowed to become dry Laurent Box

and brittle. a, space for in-

: e Lees ¥ * co sects; b, perio-

The laurel box has, however, one disadvantage piken raskilion

as compared with the cyanide bottle; for, while the = pened laurel
eaves

former requires frequent renewals of fresh leaves,
the latter will retain its power throughout a whole season or even
longer if properly managed.

One other method of killing insects must be mentioned
—one that is now employed by a number of entorhologists, and
declared by many to be the best. Make a few perforations in the

56 THE COLLECTOR'S WORK

lids of all your pill boxes, and take home all your captives alive
in these. Then, on arriving home, put all the boxes into a large
tin box with some blotting-paper that has been moistened with
the strongest solution of ammonia, and cover the tin to allow the
powerful gas to do its work.

The ammonia is not so speedy in its action as either cyanide or
laurel, but it leaves the insects perfectly supple; and though it
permanently affects the colours of many of the specimens, the natural
tints are often restored, as the gas diffuses after they are with-
drawn.

Setting Insects

Let us now see how the insects are to beset. Ina few instances,
as with some of the aquatic beetles and bugs, where the wings are
not developed, or where it is not required to extend the wings, the
setting is exceedingly simple. The only apparatus required is afew
sheets of cork and a supply of pins.

The cork may be obtained in sheets of various sizes and thick-
nesses from any cork-cutter, or from dealers in naturalist’s
appliances. The size in the present instance is immaterial, and the
thickness should be about an eighth of an inch.

The pins are to serve two purposes—some to run through the
bodies of the insects and fix them permanently, and the others
merely to keep the appendages in the desired position while the
drying is in progress. For the latter purpose ordinary draper’s
pins will suffice, but only the slender pins made expressly for ento-
mological purposes should be used for the former.

Entomological pins are made in a variety of sizes, but the
beginner cannot do better than procure a box of ‘mixed pins’ from the
dealer. He will do well also to keep a sample card of the various
sizes and their numbers, so that he may be able to order through
the post or otherwise a small quantity of any special kind required,
for it is very unlikely that the ‘mixed pins’ will contain just what
he wants in the proportion in which they are required.

Although the sheet of cork mentioned above will serve every
purpose as a setting board for certain insects, it will be greatly
improved for permanent use if it is glued to a thin slab of wood of
exactly the same size, and then covered on the other side with clean
white paper, laid on with thin paste. The wood gives firmness and
rigidity to what would otherwise be a rather fragile and too flexible
support for the pinned specimens, and the white paper covering the

THE POND-HUNTER’S MUSEUM 57

top will greatly assist the setting by providing a white background
on which the insects, mostly dark in colour, may be very distinctly
seen.

In the case of those insects which are to be set with extended
wings, different kinds of setting boards will be required. These
may be purchased ready made, but such are generally adapted only
for butterflies and moths and a few other orders of insects, and
would certainly not fulfil all the requirements of one who makes
aquatic life a special study.

The ordinary setting board consists of a walee base, covered
with a grooved piece of cork, the groove being made to accommodate
the body of the insect
while its wings are spread
on the surface on each
side.

The easiest way to
make such a board is to
cut a piece of wood about a foot long, one quarter of an inch thick,
and of such a width as to slightly exceed the length (measured from
tip to tip of the extended wings) of the largest insect for which
it is to be used. This wood is then covered with a sheet of cork
of the same size, which is glued on; and then on the top of this is
laid two other strips of cork, each a little less than half the width
of the former, leaving a space between them down the middle of
the board. As soon as all have been glued together, the board is
put aside to dry under pressure. Lastly, when quite dry, the
edges are trimmed, the surface is smoothed, and the top covered
with thin white paper which is laid on with very thin paste.

Another way is to glue a thick sheet of cork to a base of wood,
cut a groove in the cork, and then finish off as before ; but this plan
is not nearly so easy unless one is provided with suitable tools for
cutting the groove.

The accompanying figures of sections of setting boards show
three forms in common use—one with perfectly flat sides, one with
flat but sloping sides, and a third with rounded sides.

The seleetion of one or the other of these is generally only a
matter.of taste, but the pond-hunter will generally find the first
answer his purpose as well as any.

We have already alluded to these setting boards as being adapted
more particularly for the setting of butterflies and moths, of which
none of the former and only a few of the latter come within the

OLE AEA

Fic. 46.—Sercrion or A Settrinc Boarp

58 THE COLLECTOR'S WORK

province of him whose work is confined to ponds and streams ; but
with a few slight modifications, such as would readily suggest them-
selves to any interested worker, they may be rendered extremely

Fic. 47.—SEcTIONS OF THREE
Serrinc Boarps

useful for the setting of numer-
ous aquatic insects.

Without any alteration at
all, setting boards of the above
pattern will answer well for
many of the aquatic flies, suchas
the May Flies (Hphemerida),
Stone Flies (Perlide), Alder
Flies (Stalide), and Dragon
Flies (Odonata), aswell as for
the few aquatic lepidoptera ; but
it will often be found convenient
to have the groove very much
wider in those instances in
which it is desired to set out the
legs as well as the wings, the

groove in these cases having to accommodate the extended legs as

well as the body.

In setting the Lepidoptera (Butterflies and Moths) it is usual to
keep the legs folded under the body, or to bring the front pair

Fic. 48.—A BuTrTeERFLY ON THE
Setrinc Boarp

shows a simple method of setting a dragon fly.

forward while the remaining
four are folded, and for this
purpose the groove need be but
little wider than the bodies of
the insects. A pin of suitable
size is passed vertically through
the middle of the thorax, and
then into the cork at the
bottom of the groove; and the
extended wings are held in posi-
tion by means of little paper
straps which are pinned to the
board as shown in fig. 48.

The next illustration (fig. 49)
Here the wings

are held in position in exactly the same manner; and at the
same time the legs are extended in the wide groove of the board,
and secured where necessary by means of pins driven into the cork

THE POND-HUNTER’S MUSEUM 59
either in front or behind, according to the direction in which the
legs have a tendency to spring.

After these few remarks and suggestions. the reader will probably

iia)

a

$|
?

Fic. 49.—A DraGcon FLy on THE SETTING Boarp

have no difficulty in designing a setting board to answer any of his
requirements, there being little to consider besides the width and

depth of the groove.
Relaxing

It will be necessary to state here that those insects that are to be
preserved dry should, as a rule, be placed on the setting boards as
soon as possible after the return from the field, while their limbs are
still soft and supple.

We have already recommended that the winged creatures be
captured by the net or taken in pill boxes, carried home alive, and
then killed by means of the cyanide bottle, the laurel box, or am-
monia. But it is not always convenient to set them all right away

60 THE COLLECTOR'S WORK

and if put aside they soon become so dry and rigid that setting then
becomes an impossibility.

We have further pointed out that potassium cyanide renders
them very stiff, though afew days’ confinement in the cyanide bottle
often brings them back toa workable condition ; also that the laurel
box may be made to serve the purpose of a relaxer. But when a
number of pinned insects have been allowed to become dry, a more
commodious relaxing apparatus is often very useful to soften the
joints of their various appendages—legs, wings, antenne, &e.

Such a relaxer is easily extemporised as follows: Select a basin
or dish large enough to contain all the dry specimens. Pour a little
water into it, pin all the specimens to pieces of cork, and float the
cork on the water. Then cover the vessel with a sheet of glass. In
a day or two the smaller insects will have become so supple that
setting may be commenced, but the larger ones must be allowed a
longer period to undergo the necessary softening.

As the relaxing of the latter progresses there is always a danger
of the development of mildew unless some means has been taken
for the prevention of such vegetable growth ; and though this may
not always be absolutely necessary, yet it is advisable to adopt it at
all times. A drop or two of crude carbolic acid in the water of the
relaxer is quite sufficient to check any development of mildew.

Our remarks concerning the killing and relaxing of insects apply
to nearly every case likely to come within the pond-hunter’s
experience, but there are still a few points concerning the setting of
certain kinds which require or admit of some special treatment.

Some of the short-winged insects, the larger diptera for instance,
do not require grooved setting boards. They should be pinned
through the thorax, and fixed on a flat board as recommended for
the wingless species. The legs are first placed, and fixed if neces-
sary, in natural positions, and the wings may then be kept extended
by means of small strips of thick paper or thin card mounted on
pins.

Beetles

Beetles have two pairs of wings, the outer pair (elytra) being hard
and horny, and serving merely as a protection for the longer mem-
branous wings which are folded beneath them when not in use.

When beetles are to be set with their wings closed, it is usual to
pass the pin through one of the elytra, a short distance from its base,
and not through the thorax as with other insects. This of course
does not look so well as if the pin were central, but it need be but

i.

THE POND-HUNTER’S MUSEUM 61

little out of the middle line; and, for the sake of uniformity, all
should be pinned on the same side. Then as to which side shall
be chosen, this is a matter of no import-
ance if your collection is to consist entirely
of your own specimens, that is, of speci-
mens which you have taken yourself. But
naturalists generally greatly assist one
another in extending their collections by
exchanging their duplicates for those of
their friends ; and for this reason you will
see at once the advisability of a recognised
uniformity in the methods of setting and
preserving, in order that the cabinets of
collectors may not exhibit a disagreeable
variety of tastes and fancies.

Hence it will be well to observe, in the
case of beetles, that it is usual to thrust
the pin through the right elytron, as

Fie. 50.—A BEETLE

shown in our illustration. SINNED AND SET WITH
Many of the aquatic beetles are so WINGS CLOSED

small that it is impossible to pin them
without injury, even with the finest pins made, and these should be
mounted on card by means of gum.

It is particularly necessary in this case that the joints should be
so supple that-the legs, wings, and antenne are very easily secured
in their respective positions, for the gum has
very little holding power while in a fluid con-
dition.

A thin card of the finest quality should be
used for this class of work, good ‘ivory’ visiting
cards being perhaps as suitable as any for the
purpose.

The best gum to use is tragacanth, which

~4

may be obtained in the solid state from any | |
chemist. A small piece of the gum is placed w--
in a little bottle of water and set aside. It soon Fic. 51.—A sMaun

; cE‘ ye . INTE
begins to swell up enormously; and, after a BEETLE MOUNTED
. oN CaRD, EN-

time, the whole mass is converted into a thin eee

jelly, the consistency of which may be altered

if necessary to the best working condition by the addition of either
more guin or more water.

62 THE COLLECTOR'S WORK

Test your specimens first to see if they are in a fit condition for
mounting ; and if they require relaxing put them in the cyanide
bottle, laurel box, or any other relaxer for a day or two.

When ready, cover a card with the gum, set the beetle as desired
by means of a needle, and then allow it to dry.

Several small beetles may be mounted on the same card, which
may afterwards be cut into neat oblong strips, each with a single
specimen. These strips are then ready to be pinned for the cabinet.

This method of mounting is not confined to small beetles only,
nor even to small insects. It is certainly the best dry method of
preserving small insects of all orders ; but, in addition to these,
there are many large species with legs so long and slender that it
is a very difficult matter to keep them intact unless these limbs are
flattened down and gummed to a card. But in this matter the
setter must use his own discretion.

Before closing our remarks concerning the setting of insects,
we have one more case to mention, and that is the preparation of
the larger water beetles with wings extended.

For these a setting board with a very wide groove is required.
In fact the groove, which, by the way, should be shallow, must
also be wide enough to contain the body and the walking legs.

Pin the beetles through the thorax now; and, after arranging
the legs, separate the two elytra, and fix them in an extended and
slightly raised position. Now you will observe the folded membra-
nous wings displayed. Open them out carefully by means of a blunt
needle, and then hold them in position on the setting board just
in the same way as you would the wings of butterflies and moths.

Preserving Crustaceans

We may now say a word or two concerning the preservation of
freshwater crustaceans.

The smallest of these—freshwater fleas and cyclops—may well
be included under the head of microscopic life. They may be pre-
served in dilute spirit, and stored away in small specimen tubes for
future study; or they may be mounted on glass slips as permanent
microscopic objects.

Freshwater shrimps also may be well preserved in spirit. Their
natural colour will be more or less destroyed by this method, but
their form will remain perfect. If allowed to dry, their bodies
shrivel up and assume a very unnatural appearance.

Crayfishes may be preserved either wet or dry. In spirit they lose

THE POND-HUNTER’S MUSEUM 63

their natural tints, but in all other respects remain perfect. The
wet method of preserving animals possesses the advantage that they
may be dissected and examined at any future time, and parts
selected for detailed study with the aid of the microscope or for the
preparation of permanent microscopic slides. But when weight and
space are considerations, the necessary array of specimen jars and
tubes charged with a large quantity of alcohol is a great drawback
to the collector, who therefore adopts the dry method wherever
practicable, more particularly with the largest specimens.

Crayfishes may be very satisfactorily preserved in a dry state as
follows: It will be observed that the body consists of a number of
segments moveable one on the other, the first one (really several
segments fused together), called the cephalo-thorax because it con-
sists of both head and thorax combined, being much larger than the
smaller ones which form the abdomen.

Sever the body in two by cutting through the soft structures
between the cephalo-thorax and the abdomen, and then remove the
internal organs and flesh by means of a hooked wire, assisted by the
occasional use of a small brush.

In the case of small specimens this is quite sufficient, but larger
ones should have their front claws removed and cleared in a similar
manner.

Now set out the parts on a board to dry, having placed all the
appendages in the position they are finally to assume. The drying
may be conducted most advantageously in the open air, not only
because this is the quickest plan, but also because, however carefully
the clearing of the soft parts may have been accomplished, there is
sure to be enough remaining to give a questionable taint to the
atmosphere of an ordinary apartment.

A few days’ access to the free air in dry weather is quite sufti-
cient to complete the drying of the parts, which may then be
fastened together by means of a little coaguline.

At least two crayfishes should be preserved for future reference
and study, one being placed in the collection so as to show the upper,
and the other the lower surface.

Freshwater Shells
We liave one other class of animals to deal with in this chapter,
viz. the mollusea.
The aquatic species of this class are all protected by shells, and
it is common for beginners in this branch of natural history to

64 THE COLLECTOR’S WORK

confine, themselves to the collection and study of the shells only,
neglecting altogether the peculiarities of the soft-bodied animals
which they enclose.

This, however, is easily explained. The shells are always
interesting and frequently very pretty objects; and are, moreover,
easily preserved. But it will be admitted without hesitation that
the shells are, after all, only the homes of the creatures concerned
—that they are merely the lifeless calcareous secretions of the
‘mantles’ of the animals which they protect; and that, although it
is possible to identify every species of the aquatic molluses by a
careful observation of the shells alone, yet he who confines his
attention to these knows but little of their natural history.

What, then, should the pond and stream hunter do, and, equally
important, what should he not do ?

To take up the latter question first, let me impress upon him
that he should never be in a hurry to kill the animals in order to
obtain the clean shells. A few of every species taken should be
placed in the aquarium for the observation of their habits. And
then, having selected what is required for this purpose, always set
aside a few for preservation in fluid, in order that the animal itself
may always be at hand for reference and examination when fresh
specimens are not to be obtained.

In cases where shells only are required, it is usual to kill the
molluses by immersion in boiling water, and this is undoubtedly the
most merciful way of dealing with them. But this causes the
animals to so contract and shrink within their shells that they are
practically worthless for the examination of some of the softer
structures.

Perhaps the best way to proceed with those which are to be pre-
served entire is this: Place the living molluscs in water, and let
them remain till their bodies are as fully extended as during their
most active moments—till the headed members are crawling with
their tentacles fully protruding, and the bivalves have their ‘ feet’
and ‘siphons’ extending from their gaping shells.

Now add a solution of corrosive sublimate to the water. This
must be done very gradually, and the animals will soon succumb to
the effects of the poison, dying with some of the softer parts still
visible and well extended. When dead, they may be placed in weak
alcohol, not stronger than about twenty per cent. Here they must
remain till colouring matter ceases to be extracted from their struc-
tures, and then they should be taken out, lightly brushed all over

THE POND-HUNTER’S MUSEUM _—_65

with a soft camel-hair brush, and finally housed in labelled bottles
with stronger spirit, which, however, should not be strong enough to
cause them to shrink.

In this manner it is possible to obtain a collection of molluscs
that reveal characteristics which are aids to identification and
classification, and which are important supplements to those features
that are revealed by the empty shells alone. Such specimens, too,
if properly preserved, are always available for dissection, though for
this purpose they are not so good as freshly killed molluscs.

We must now turn our attention to the preservation of the shells,
dealing first with the univalves or one-shelled molluscs, more com-
monly spoken of collectively as the snails.

After these have been killed by immersion in boiling water as
already directed, the animals are extracted by means of a pin with
a bent point, of course using a very fine pin for the small species.

The extraction should be performed with care, pains being taken
to remove the animal entire, or a portion will remain within the
small whorls of spiral shells, quite beyond the reach of the extractor.

This, however, is often unavoidable ; and in such cases, as well
as with some very small shells from which it is almost impossible to
remove the animals with a pin, the only way to clear out the soft
matter is to allow it to decompose in water, which should be fre-
quently changed during the process.

As soon as the shells are cleared they should be brushed lightly,
and then put in an airy place on a sheet of blotting-paper to dry.

Some of the freshwater snails are provided with a shelly or
horny lid (the operculum) like that of the marine periwinkles and
whelks, by which the shell is closed when the animal retires. This
should always be preserved with the shell. It should never. be
gummed or cemented to the shell itself, but placed in such a
manner that it can be easily removed for the examination of its
interior surface as well as of the interior of the shell. The ‘ body
whorl’ of the shell may be lightly packed with cotton wool, to
which the operculum may be fastened by a little gum or coaguline.

The shells of the larger bivalves are to be treated in this way :
After the animals have been killed in boiling water, the muscular
pillars which hold the valves together must be cut through with a
sharp penknife or scalpel, and the body removed. It will now be
seen that the two valves are kept open by the elasticity of the strong
ligament at the hinge.

Gently press the valves together till they are in close apposition,

r

66 THE COLLECTOR’S WORK

and then tie them round with cotton or thread, and set aside to
dry. They will then remain closed after the binding has been

removed.
Some of the smallest of the bivalves are too delicate for contact
with the point of a knife. They may be cleared of their contents
by simply allowing the animal

matter to decompose in water, the
ae) water being changed at intervals
till they are quite clean. The valves

Fre. 52.—Sprina Cure ror Houp- may then be held together during

ING SMALL BivALvE SHELLS the drying operation by means of

little spring clips, the greater por-

tion of the moisture having been previously removed by strips of
blotting-paper.

One specimen of each bivalve shell should always be preserved
in such a manner as to allow the structure of the hinge to be
examined. This can be easily done by opening the shell wide and
placing just sufficient weight on it to keep it open till the ligament
is perfectly dry.

Lastly, a word or two concerning the cleaning of the exterior of
the shells. In many cases they will be found incrusted with the
sediment of ponds, and still more frequently will they be partly or
entirely covered with vegetable growth.

This may be removed by means of a brush—a tooth-brush answer-
ing admirably for the larger and thicker kinds, but of course a
softer brush for the delicate ones.

There will be no need, however, to clean every specimen in this
way. A layer of vegetable growth or other deposit gives a natural
appearance to the shell; and, as long as one or two of each species
are sufficiently cleansed to show the details of form and structure,
the others may with advantage be allowed to exhibit those appear-
ances which so commonly characterise the tenanted homes of the
pond and stream.

The Collection

It is not long before one who is deeply interested in natural
history finds that he has become the owner of a gradually in-
creasing collection of objects that have been put on one side at
various times for future examination or because of some unusually
pretty appearance.

At first no special difficulty arises, the specimens being deposited

a
v=
5

THE POND-HUNTER’S MUSEUM 67

without definite arrangement on any spare shelf or in any unoccu-
pied corner. But after a time matters present a more serious
aspect. ‘Let me see; where shall I put this specimen jar, and
what shall I do with this box of insects ?’ says the young naturalist,
whose treasures accumulate in proportion as his love for his subject
grows more intense.

He sees that confusion is beginning to prevail, and soon awakens
to the melancholy fact that the space at his command is strictly
limited. With a puzzled expression he scans his present situation,
and thinks over the various alternatives before him.

Shall he cease to add to his accumulating store of treasures ?
No; that is quite out of the question, for not only must he study
the objects collected at his leisure, but they must needs be always
at hand for comparison and the determination of their relationships.
And the negative reply is still more emphatic when for a moment
he entertains the idea of discontinuing his observations.

Something must be done, and that speedily. Some kind of
accommodation must be provided in order that the objects may be
saved from destruction, and that they may be so arranged as to
form a convenient work of reference as his study proceeds.

Other difficulties then arise, and these seem at first almost
insurmountable. How nicely things could be managed if his space
were infinite and cash without limit !

But the first difficulty can be soon diminished. A few shelves
here and a few compartments of some kind there will enable the
present store to be set in order, with an allowance for a further
increase. But the second consideration still stands out prominently
before the collector—How shall he arrange them ?

It is quite possible that some of my readers are so fortunately
situated that the pecuniary side of the question presents no
difficulty at all. Their wants are explained to some obliging dealer,
or their rough plans exhibited to a neighbouring cabinet-maker, and
the ordinary apartment develops like magic into a luxurious private
museum and naturalist’s laboratory combined.

Such readers, however, are undoubtedly in the minority, hence
it is our duty to provide hints for the assistance of those who
require .a suitable but inexpensive storehouse for their specimens.
Let us see, then, what can be done in this direction.

First, as regards the objects that have to be preserved in fluid,
those in jars and bottles simply require shelf accommodation,
but should always be protected from dampness and dust wherever

F2

68 THE COLLECTOR’S WORK

possible. A damp atmosphere, though it cannot affect the specimens
themselves, causes considerable annoyance by loosening the labels.
Dust, too, does no injury to bottled objects, but a cleanly appearance
and a great saving of time will be the result if the specimens can be
stored in a well-fitting cupboard or cabinet.

All the very small objects that require a fluid preservative should
be stored in specimen tubes fitted with good corks. The tubes may

then be laid side by side in cardboard glass-

‘Semis topped boxes or in shallow trays or drawers.

| The labels in this case may be gummed

| round the top of the tubes, leaving nearly the

whole of the length clear for observation of

the contents ; or each tube may be tied to a

strip of card, as shown in fig. 538, and any

desired memoranda written thereon instead
of on a gummed label.

Insects and other creatures preserved
in a dry state present greater difficulties, for
it is no easy matter to keep them quite out

of the reach of certain museum pests which
Hid. 53:—A. SPHOIMEN | Govour portions of their bodies, often causing
TUBE MOUNTED ON é 3
a Carp the remainder to crumble away. Nothing
can be considered highly satisfactory for these
except the well-made cabinets and store boxes made by experienced
hands for the express purpose.

It is not absolutely necessary, however, that glazed and practi-
cally airtight compartments be used, provided a liberal supply of
some suitable insecticide is introduced and renewed as occasion
requires, and that a constant watch is kept for the intrusion of the
little destroyers.

Glass-topped cardboard boxes, such as are largely used by
drapers for their small goods, are by no means to be despised.
Narrow strips of sheet cork glued on the bottoms of these serve
to hold the pins firmly; and a good allowance of camphor or
naphthaline (albo-carbon) in each will prevent the intrusion of
destructive pests.

The only advantage of the glass top is to allow one to see at a
glance what each box contains, but it must be remembered that
continued exposure to light will very soon cause the natural colours
of the specimens to fade. Hence, if of necessity this inexpensive
accommodation be chosen for the specimens acquired, the boxes

THE POND-HUNTER’S MUSEUM 69

should be shut up in some kind of case so that light as well as dust
may be entirely excluded. By securing a dozen or so well-made
cardboard boxes, and then making a little cabinet or box in which
all can be snugly packed, one can provide a very satisfactory,
although extremely cheap, storehouse.

Intermediate between this arrangement and the costly cabinets
of the naturalists are the store boxes supplied by dealers. These
are wooden boxes, of various
sizes, and of such a depth that
they will contain a double layer
of specimens, for which purpose
they are lined with cork both on
the top and bottom. .

The shells of aquatic molluses
should be arranged in cardboard
or chip boxes of suitable size.
A very inexpensive and neat plan
is to make a collection of ordi-
nary matchboxes — the inner
sliding portions—re-cover them
with good white paper, divide 44 54.—A SrorE Box ror Dry
them into compartments by SPECIMENS
strips of card for the smaller
species, and then lay the shells in them on beds of wadding. This
will prove very satisfactory for the majority of British freshwater
shells, but special boxes will have to be procured for the few large
bivalves.

These larger boxes should, for the sake of neatness and economy
of space, be in size exactly a multiple of the smaller, so as not to
interfere in any way with the uniformity of the rows or columns in
which they are placed.

It is certainly advisable to keep the smaller shells in glass-topped
boxes. These may be the ordinary glass-topped pill boxes supplied
by dealers, or pieces of glass could be obtained from any glazier of
exactly the size to cover the square boxes used.

The best arrangement for specimens kept in drawers or boxes,
whether dried or preserved in tubes, is that of vertical columns, in
which the various species are placed in their proper scientific order.
Each column should be headed by the name of the family to which
its specimens belong. Immediately below this is placed the name
of the first genus of that family, and then follow the specimens or

70 THE COLLECTOR'S WORK

series of specimens belonging to that genus, each species having its
specific name below it.

The collection should, as far as possible, illustrate the various
stages of those creatures which undergo metamorphoses. Jor in-
stance, in the case of aquatic insects, the larvee, pupa, and even the
eggs may appear in company with the perfect form, thus rendering
the collection of far greater value than it otherwise would be.

As regards the labelling of a private collection of natural objects
there is a difference of opinion. It has been said that ‘if the
specimens are not worth knowing they are not worth having.’
And, it may be added, ‘if well known, why label them?’ This is
all right as far as it goes; but it must be remembered that each one
of the specimens is at first new and unknown to the collector or
observer; and for this reason alone he might attach a label till the
object is familiar both by name and by sight. Further, it may be
hoped, there are but few naturalists who would not be pleased to
make use of their collections for the benefit of their friends, and to
these the names would probably prove very useful indeed.

Again, what are the labels to show—names only? By no
means. The naturalist is not only interested in the mere identity
of his treasures. He is equally concerned about their habits,
habitats, food, dates of capture, and various other matters, all of
which should appear in the form of memoranda, either on the label
beneath each specimen, or, which amounts to the same thing, in his
note book under the respective name.

A good museum has been rightly defined as ‘an instructive
collection of labels, illustrated by specimens ;’ and in many cases
it is, to my mind, a matter of doubt as to which could best be spared
—the specimen or its label. And I should strongly advise young
naturalists to label every specimen in their collections, not necessarily
with the names where these are well known to them, but with
dates, localities, and any interesting observations made either at
the time of capture or subsequently.

vfs

CHAPTER V
AQUARIA AND THEIR MANAGEMENT

I HAVE already referred to the fact that many household utensils
may be converted into successful aquaria such as will serve all
the purposes_of the naturalist, and that the more expensive ‘ bell’
aquaria and rectangular or polygonal ‘tanks’ are required only
when it is desired to combine the ornamental with the useful. And
I see no reason whatever why the lover of aquatic life should not
place some of his pets in a beautiful home where their graceful
movements and interesting habits may be easily admired, and
where their forms and colours may be blended and contrasted with
the equally admirable forms and tints displayed by a judicious
selection of growing vegetation and a tasteful rockery, just as the
botanist who rears plants for his own study and research adds to
the charm of his collection by arranging them in such a manner
as to make his garden or conservatory an ornament to add to
the beauty of his home. All these considerations will be borne in
mind in the present chapter, which is to be devoted to hints and
suggestions concerning the formation and management of fresh-
water aquaria.

In the first place let it be clearly understood that a single
aquarium is practically useless to the student of freshwater life
unless he is content to give attention to various species alternately,
keeping only those in captivity at any one time that live in
harmony. To prove this, put all the takings of a pond hunt on a
summer’s day into an aquarium together, and watch the result.
The ensuing scene is one of constant warfare, the stronger and
more voracious (not necessarily the larger) species attacking and
devouring the more harmless and quiet, till at last the field, strewn
with dead and partially devoured victims, is held by the few sur-
viving conquerors, and the water is rendered putrid and perhaps
dangerous by the products arising from the decomposing remains

72 THE COLLECTOR'S WORK

of the vanquished. A general turn-out and cleansing of the aqua-
rium will now be an absolute necessity. ‘

Of course the carnivorous creatures must be provided with food,
and perhaps it is only fair that they should have their natural diet,
but they should be kept in a separate compartment, and be supplied
with no more food than they devour.

Those who have no desire to establish an ornamental aquarium,
but wish to reserve all their energies for the stern study of fresh-
water life, need have no other utensils than are daily demanded in
the domestic service. Here are some suggestions :

Tor fishes and the larger molluses, nothing is better than a large
tub placed in a shady corner out of doors. It is really much
superior, from a naturalist’s point of view, to a glass aquarium of
any kind, as it more nearly fulfils the conditions of the natural
haunts of the creatures concerned. Like the pond and stream, it
leaves a considerable amount of surface exposed to the atmosphere,
and admits light from above only. A layer of sand or fine gravel
at the bottom supplies a good natural bed on which the ‘ bottom
fish’ and the bivalve molluses can rest and burrow, and in which
may be planted a selection of water plants; and a mass of loosely
piled irregular stones will give the shelter and semi-darkness which
the more seclusive species require.

If an aquarium of this description is to contain creatures that
inhabit rapid streams and delight in clear running water, it is
simply necessary to place the vessel under a water tap, and bore a
hole in the side of the tub, a few inches from the top, for the waste
to flow away.

Then again, for the rearing of amphibians through their earlier
stages the tub is, par excellence, just the thing. For this purpose
the water should be only a few inches deep, and well supplied with
weeds ; and piled stones should reach above the surface as a resting
place for those whose strictly aquatic life has terminated.

Crayfishes and freshwater shrimps delight in shallow running
water, with a sandy bottom and plenty of hiding places among
stones ; and nothing serves the purpose better than a shallow tub or
stoneware trough with a constant supply and a waste pipe. It will
occur to the reader, however, that a strainer of gauze or muslin
should cover the exit for waste in order that the small crustaceans
may be prevented from escaping.

A large aquarium such as that which we have already recom-
mended for fishes and the larger molluses might well be used for the

AQUARIA AND THEIR MANAGEMENT 73

larvee of aquatic insects and other creatures of small and moderate
size when a number are required as ‘ stock,’ but those which are to
be kept under close observation in order that their habits and meta-
morphoses may be watched may be transferred for the time being to
earthenware vessels or, in the case of very small species, to glass
jars ; but in all cases a layer of sand cor gravel and a supply of grow-
ing weed must be provided for purposes of aération as well as for
the sustenance of the vegetarians.

Glass vessels of all kinds have the objection that they admit too
much light, and thus they not only cause the inmates to exist under
conditions unnatural to them, but also encourage the rapid develop-
ment of confervoid vegetation which sooner or later covers the glass
so densely that observations are impossible, while sometimes the
whole of the water is converted into one green mass. This being the
case, itis advisable to shut off much of the light by a sereen of some
kind which can be readily removed at times when the contents are
under inspection. Cylinders of paper, more or less opaque, may be
made to drop down over the jars loosely. Or, if preferred, a piece of
tissue paper may be pasted permanently over the side on which
the strongest light falls. The former method is perhaps preferable,
for when the moveable screen is lifted from its position the objects
within the jar are more easily watched than when backed with a
semi-transparent ground.

Whatever be the form or nature of the aquaria used, direct sun-
light should. be avoided, especially the powerful rays of midday ;
and to this end a window with a northern aspect should be chosen
if possible.

So far we have confined our remarks to nothing but the rudest
appliances which, although they supply absolutely all that is neces-
sary for the successful study of freshwater life, constitute nothing
of an ornamental character, but rather tend to give an appearance
of untidiness and disorder to the naturalist’s apartment; but we
shall now consider briefly a few forms of aquaria that may be made
to please the eye as well as to instruct the mind.

Of these the well-known bell glass is by far the most generally
used and most easily procured. Yet how miserable are the attempts
to convert it into an object of beauty, and how imperfectly known
are the principles on which its successful management depends! We
commonly see this vessel containing nothing whatever with the ex-
ception of a few neglected fishes. No soil of any kind to form a
bed, no hiding place for a cool shelter from the blazing rays to which
the creatures are so often exposed, and not a scrap of weed to exer-

74 THE \COLLECTOR’S WORK

cise a purifying influence on the water or to relieve the monotony
of the scene.

It is no wonder that so many discontinue aquarium keeping after
a very short experience. The amount of attention necessitated
through ignorance, and the great trouble and loss of life caused by
mismanagement, make the owner give it up in disgust and declare
that the aquarium is not nearly worth its cost.

But even the bell-glass aquarium, unnatural as it is, may be
made a success in every respect if due regard be paid to the require-
ments of the creatures contained therein and to the general principles
which are involved. But perhaps it will be better just now to con-
fine our remarks only to the selection and construction of the different
forms of vessels that may be used, and then deal with the manage-
ment of aquaria collectively.

Fic. 55.—Tue RectranecutarR Tank

A square or oblong ‘tank’ may be easily made at a low cost.
Only one side need be of glass, the remainder being either of wood,
metal, or slate.

If wood be chosen, first decide on the size of the base, which will
generally be arranged according to the space at disposal, or the table
or other rest on which the aquarium is to stand. This should be of
hard wood—mahogany, teak, and oak are all good for the purpose—
about one inch or more in thickness, well levelled and smoothed on
the upper surface.

The wood for the back and the sides need not be so thick as that
which forms the base, half an inch being quite sufficient for indoor
tanks with a capacity of only a few gallons. The three pieces chosen
should be neatly dovetailed together after having been faced, and

———a -

AQUARIA AND THEIR MANAGEMENT 75

the grooves cut to receive the glass. When this is done, place the
four sides temporarily in position on the base, and pencil out on the
latter the exact sizes and situations of the grooves to receive them.
These grooves need not be deep, and when they are ready the back
and sides should be held firmly by screws driven through the base
from below.

Now follows the important operation of rendering the structure
perfectly watertight. A liberal supply of melted pitch should be
allowed to run freely round all the joints and in the grooves, and
the whole surface of the wood must also be covered in order to stop
all the pores. While the pitch in the grooves is still hot and soft,
push the glass in its place, and then smooth over the whole of the
pitched surface with the flat face of a hot iron. A warm iron wire
may also be well worked round the edges of the glass, both inside
and outside.

The tank is now ready for water, but it is not advisable to intro-
duce any living things for a day or two, as the water at first may
dissolve out harmful impurities from the pitch, and may also partake
rather freely of the odour of the pitch itself.

Slate is far preferable to wood for rectangular aquaria, but is
more expensive, and much more difficult to work. Nevertheless it
is to be strongly recommended to those who do not mind the extra
cost and the time required for the cutting and grooving, or to those
who can get the slabs ready cut and prepared by an experienced
workman. In this case all the parts fit in grooves, and the slabs
are held firmly together by metal rods and nuts. It will be far
better, too, to use the cement recommended below instead of the
pitch.

A very neat tank may also be made by soldering together a frame-
work of ‘angle zinc,’ and attaching it to a base of sheet zine sup-
ported on a slab of wood. Roofing slates may then be used for the
back and sides, and glass, as usual, for the front; or all four sides
may be of glass as a matter of convenience, but if so the back and
ends should be rendered opaque by means of a coat of paint or a
layer of paper on the outside.

In making up a tank of this description care must be taken in
the preparation and selection of a good cement, for pitch, though it
answers well for wooden aquaria, does not adhere so firmly to metal
and slate.

A good stopping may be made by mixing two parts of litharge,
two of plaster of Paris, two of very fine sand, and one of finely

76 THE COLLECTORS WORK

powdered resin, and then working the mixture up into a putty with
boiled linseed oil and a little driers. This should not be made until
required, and must be allowed a week or two to harden before water
is put into the aquarium.

Whatever be the materials used in the construction of a rect-
angular tank, it should always be filled with water and allowed to
stand for a day or two before it is stocked. This will not only give
a good opportunity of thoroughly testing its water-resisting power,
but will allow any objectionable soluble matter in the cement or on
the surface of the other materials to be dissolved.

This water is then run off, and the final preparations for the
reception of the living things may be conducted as follows, bearing
in mind that the instructions here given apply to all aquaria, what-
ever be its form or size or the nature of the proposed inhabitants.

First introduce a layer of clean sand to the depth of a few inches.
If the sand be taken from the bed of a neighbouring rapid stream it
may not require any washing, but if obtained in a sand-pit or from
the sea-shore a thorough cleansing will be absolutely necessary, in
the former instance to remove clayey matter and miscellaneous
impurities, and in the latter case to dissolve out all traces of salt.

The best method of washing is as follows: Place a clean tub or
large pail under a running tap, and the sand to be washed at the
left of it. Then take the latter, a handful at a time, and drop it
gradually into the running water while you keep the whole in a
vigorous motion by stirring it round with a stick held in the right
hand. Continue this till the water runs away perfectly clear, and
till a drop of it, evaporated to dryness in a perfectly clean watch
glass, leaves no more residue than a drop of the clean water direct
from the tap. This latter test is necessary because water which
is perfectly pure to all appearances may contain soluble matter,
possibly of an objectionable nature.

When satisfied as to the cleansing of the sand, put it into the
aquarium, and proceed at once to plant the weeds that you have
selected. In this matter it will be advisable to introduce a variety
of vegetable life rather than to confine yourself to any one species ;
for by so doing you not only give yourself an opportunity of be-
coming more intimately acquainted with the various forms of aquatic
vegetation, but will also learn, more rapidly than you otherwise
would, which species thrive best under the conditions to which you
have subjected them.

As already intimated, the aquatic plants serve various purposes.

AQUARIA AND THEIR MANAGEMENT 77

They are not only beautiful ornaments in themselves, capable of
producing what may truly be termed an aquatic flower-garden, but
they keep up a constant supply of oxygen gas for the respiration of
gill-breathing animals, and also represent so much food for the
vegetable feeders. And since some of these plants are far more
ornamental than others, and some species are also particularly
liberal in their evolution of oxygen, and, again, some are special
favourites as articles of diet, it will be seen that the selection be-
comes a matter of considerable importance. This being the case, we
shall presently devote a little space to the consideration of some of the
most useful and interesting species, dealing with their peculiarities as
far as the management and well-being of the aquarium are concerned.
But to return to our task.

il st i

J

Fic. 56.—FIm.ina THE AQUARIUM BY MEANS OF A SIPHON

After fixing a liberal supply of aquatic plants by their roots in
the bed of sand, scatter a layer of clean pebbles of various sizes, and
build up a few little rockeries of rather large and irregular stones,
piling them loosely in such a manner as to leave numerous hiding
places for those creatures that prefer their hours of seclusion, and
then proceed to run in the water.

In this matter be as gentle as possible, so that none of the
arrangements may be disturbed. The best way is to mount a large
pail of water above the level of the top of the aquarium, and then
introduce a bent tube—glass, or new ‘ compo’ gas pipe—the shorter
arm of which reaches to the bottom of the pail, and the longer
one dips into the aquarium. By withdrawing air from the tube by

78 THE COLLECTORS WORK

suction at the end of the longer arm till the water reaches a level in
that arm below the surface of the water in the pail, the water will
run through, and continue to do so till the pail is empty. A tube used
in this way is termed a siphon, and forms a ready means of either
filling or emptying an aquarium. The advantage in the former case
over more rough and ready methods of filling aquaria is that a steady
stream of water may be allowed to flow in without disturbing the
plants or disarranging the sandy bed.

An aquarium fitted up as described will answer most but not all
the purposes of the student of freshwater life. In ita great variety
of creatures may be kept under almost perfectly natural conditions,
and therefore observed to the best advantage. But, as we have
already hinted, there are living objects so small that they would be
lost in any moderately sized aquarium, and should therefore be kept
in jars or other small vessels where they can be conveniently
observed. Again, in ponds we meet with many creatures that are
always to be found lying on or burrowing into soft mud. These
should be kept by themselves in a vessel with a layer of mud from
the pond from which they were taken.

Matters of this description, however, are so numerous that it
would be impossible to deal with them here ; but a careful observer
at work in the field, who is in the habit of closely watching the
habits of animals, and who endeavours to keep all his captives under
conditions corresponding with those under which he found them,
will have little difficulty in keeping and rearing all he requires.

The success of an aquarium depends to a considerable extent on
the manner in which it has been started. If well fitted up, in the
first instance, with a well-balanced proportion of animal and vege-
table life, and constructed or shaded in such a way as to exclude
extraneous light, then there is no reason why it should not remain
in a satisfactory condition for a very long time without the slightest
attention. But whether this is so or not, it is well to know that
the successful and intelligent management of aquaria depends on the
knowledge of certain of the principles underlying animal and vege-
table growth. Perhaps the most important matter of all is the
arrangement for the proper aération of the water; and as this is a
consideration of great moment to the aquarium keeper, we shall now
study in detail the different ways in which the necessary amount of
air may be maintained.

In the first place let us see what changes are produced in water
as a result of the respiration of those creatures that obtain the

AQUARIA AND THEIR MANAGEMENT 79

whole or part of the air they require from the liquid in which they
live.

If we put some water from any pond or stream or from any
source of domestic supply into a test tube or small glass flask and
then apply heat, we shall soon observe little bubbles of gas clinging
to the sides of the vessel, and after-
wards detaching themselves and
rising to the surface. These bubbles
consist of gases which have been
absorbed from the atmosphere, and
are principally composed of oxygen,
nitrogen, and carbonic acid gas.
The first of these is the great sup-
porter of animal life, and is there-
fore the one which must be replaced
as fast as it is consumed by the
aquatic creatures. The other two,
though not required by animals,
are not in themselves objectionable
to them ; but the last is essential to
the green aquatic plants, and will
be presently considered in relation
to their requirements.

The oxygen gas is absorbed in
considerable - quantities by the
breathing organs of the truly aquatic creatures, and is used up in
their bodies partly for the oxidation of waste carbonaceous matter,
thereby giving rise to the formation of carbonic acid gas, which is
being continuously passed into the water by the same organs that
imbibe the oxygen. Thus the water is being continually deprived
of its life-supporting gas, and is constantly gaining the useless (to
the animals) product of oxidation formed by the union of carbon
and oxygen.

If, then, fishes or other water-breathing animals are kept in a
limited supply of water with no arrangement for the renewal of
oxygen, it is plain that the water must sooner or later lose its power
of supporting animal life, and disaster must follow. If the inmates
of such an unsatisfactory aquarium include fishes, we are warned of
the coming danger by their movements. Finding the bulk of the
water powerless to supply them with sufficient oxygen to allow them
to live in comfort, even when they considerably increase the rate of

Fic. 57.—Heatinc WATER IN A
Test TuBE

80 THE COLLECTOR'S WORK

their respiratory movements by a much more rapid succession of
gulps of water to bathe the gills, they instinctively rise to the surface,
where the contact with the air allows oxygen to be slowly absorbed.
So we see them skimming the surface, and gasping in their endea-
vours to secure a requisite amount of air.

Such a scene as this will suggest at once a remedy—run out all
the water and introduce a fresh supply. But it is tiresome and in
other respects unsatisfactory to be compelled to change the water

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Fic. 58.— ARRANGEMENT FOR A FOUNTAIN IN THE AQUARIUM

at regular intervals, those intervals varying with the number of
aquatic animals in proportion to the quantity of water. Other
remedies will suggest themselves, such as keeping up a continuous
current of water, or forcing air into the water by some mechanical
contrivance. The former of these will probably be the more con-
venient plan in the hands of most amateurs, but both are commonly
employed, and will therefore be considered.

Should the aquarium be situated near a water tap and a sink

AQUARIA AND THEIR MANAGEMENT 81

there will be no difficulty whatever in arranging for a constant
current. Simply carry a pipe over the top for water to run in, and
connect a waste pipe at the bottom or side to carry away the excess.
The waste pipe should of course be larger than the supply pipe, in
order that there may be no danger of overflow; and for the same
reason the inner opening of the waste pipe should be covered with
a hemispherical cap of wire gauze, otherwise it may be stopped by
floating matter, such as a fallen leaf or the body of a dead fish ; and
the cap of gauze will also guard against the escape of the smaller
living objects of the aquarium.

A little fountain at play in the middle of an aquarium not only
has a very pretty effect, but is also one of the best means of carrying

RRERERER RRR SS.
FOO ELL LL. rs re > =

Fic. 59.—ANoOTHER ARRANGEMENT OF THE FoUNTAIN PIPE

the necessary air supply into the water, for a fine jet of water, thrown
into the air and broken up into a number of little globules, exposes
so much surface to the atmosphere in proportion to its bulk that it
falls saturated with oxygen.

The neatest way to arrange such a fountain is to bore a hole
about a half or three-quarters of an inch in diameter in the middle
of the base of the aquarium, and to fit in this a cork through which
runs a tube that reaches to the surface of the water; and then to
fix on the top of this a little jet made by drawing out a piece of
glass tubing in a gas flame. The jet may be connected by means
of a small piece of indiarubber tubing, while the tube projecting

G

82 THE COLLECTOR’S WORK ~

from the cork below is made to communicate with the water
supply. .

Should there be any difficulty in the way of boring a hole in the
bottom of the aquarium, a piece of very small ‘ compo’ gas piping
may be bent over the top in one of the corners, and then carried to
the middle of the bottom, from which point it should rise perpen-
dicularly to the surface to receive the jet. This arrangement is
shown in fig. 59.

It must be borne in mind, too, in connection with this method
of aérating the water, that there is no need whatever of making any

WNMtgy psig dg tit 74

SIS ZZ

NAHAS
C Bie
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Fic. 60.—ANoTHER Mertuop or AéRATING THE WATER OF AN AQUARIUM

connection with the house supply, for water more or less deficient
in oxygen may be taken from the aquarium, to which it is returned
again after having been exposed to the air in the form of a fountain
jet. A sketch illustrating one of the many ways in which this may
be done is given on page 80. A jar or other reservoir provided with
a tap or a siphon tube is placed on a shelf or preferably, quite out
of sight in a cupboard, some feet above the level of the aquarium ;

—

AQUARIA AND THEIR MANAGEMENT 83

and the tap or tube, as the case may be, is securely connected with
the fountain jet. Water may then be dipped from the aquarium and
‘thrown into the reservoir, whence it returns with an increase of
oxygen derived from the air.

In the case of public aquaria, air is often forced into the water
by means of some kind ef pump. This is all very well where the
tanks are many and large, and where the cost of the necessary
machinery is not a matter for consideration; but for the amateur
with only one or two small tanks, this method is out of the question.
But an equally good means of forcing air into the water is practi-
cable on the smallest scale. Make a very fine jet by drawing out a
piece of glass tubing in the gas flame, and connect this securely
with a water supply in sucha way that it points downward obliquely
towards the centre of the aquarium. The pressure must be consider-
able, the house cistern or the improvised jar-cistern previously
mentioned being several feet above the jet, and then the water rush-
ing from the latter, which in this case must be above the level of
the water in the aquarium, carries with it as it descends numerous
little bubbles of air. It will be seen from what has been said that
in this case, too, the water for the aérating jet may be taken from
the aquarium itself if no other convenient supply be handy ; more-
over, if this method be adopted there will be no need for a pipe
and sink for waste ; but a fresh supply is always to be preferred if
that in use shows any signs of becoming putrid or turbid.

We have now considered all the principal methods of maintain-
ing the air supply in aquaria with the exception of the best, and that
is by means of the influence of vegetable life. The process of
respiration in plants is similar to that of animals, the plants inhaling
oxygen, which is required for the oxidation of the tissues, and which
is in part converted into carbonic acid gas. But in connection with
the function of nutrition in green plants there are other changes
in progress—changes which affect the composition of the atmosphere
far more than those associated with respiration.

During the daytime large quantities of carbonic acid gas are
absorbed by green vegetation. This isdecomposed within the plant,
the carbon it contains being added to the solid structures of the
plants, and the oxygen being set free into the air or, in the case of
aquatic plants, into the water. Thus the balance of the double
action of plants, as affecting the composition of the air, is considerably
against and opposed to that of animals.

If, then, animals diminish the proportion of oxygen in the air

a2

S4 THE COLLECTOR'S WORK

which they breathe, and add to the quantity of carbonic acid gas;
and green plants, on the other hand, increase the amount of oxygen
and reduce the carbonic acid gas, it is clear that a combination of
animal and vegetable life in a certain proportion is capable of main-
taining a constant composition of the atmosphere.

This is practically the case in nature, and a similar balance of
life may be maintained in even the smallest aquaria by a judicious
selection of animal and vegetable life.

Rules have been laid down in this matter for the guidance of
young and inexperienced aquarium keepers, giving the number of
animals of different kinds that may safely be kept in aquaria of
certain capacities, and also the approximate amount of vegetation
necessary to maintain the balance of life; but such rules are only
approximate, and are not likely to aid a beginner half so well as
his own observations.

However, in our endeavours to adjust the proportion of animal
and vegetable life inthe aquarium, we must be careful to distinguish
between the true aquatic breathers and those which obtain their
air direct from the atmosphere. The former include all fishes and
aquatic molluscs, also the aquatic crustaceans, many insects, and
numerous lower forms of life. But the introduction of some insects,
such as water beetles, water bugs, &c., need not enter into the
computation at all, for they rise to the surface for all the air they
require. Newts also make no demand on the water for their oxy-
gen except for the small amount absorbed through their soft and
moist skins.

A careful observation of the aquarium will always suffice to show
whether the balance of life is well maintained. If we find the death
rate high, and observe the fishes skimming the surface of the water,
we may be sure that the vegetation is inadequate for the production
of the required amount of oxygen; and the introduction of a few
inore plants nay set matters right. If, on the other hand, we find
a very luxuriant vegetable growth, with a rapidly increasing quan-
tity of foliage, and all the animals apparently at ease and thriving
well, we may venture to make cautious gradual additions to the
animal life, providing we carefully watch the results.

In all aquaria, whatever be the means employed for the aération
of the water, a certain amount of air will always be absorbed direct
from the atmosphere; and, of course, the larger the area of the
surface of the water, the greater will be the volume of air ab-
sorbed.

AQUARIA AND THEIR MANAGEMENT 85

Tt will thus be seen that a broad and somewhat shallow
aquarium has, in the matter of air supply, a decided advantage over
one that is narrower and deeper. This difference, however, though
always deserving of consideration, is not of great importance when
the aquarium is well supplied with vegetable life. In fact, tanks
may be managed with so little regard to this external means of
aération that they may even be covered with glass plates to exclude
dust. But, persenally, I am not inclined to recommend this; for
as a rule but little dust floats about in places in which our aquaria
are situated; and although they may be richly supplied with air
apart from a direct atmospheric source, yet it is impossible to have
too much, and it is also advisable to allow a perfectly free exit for
any products of decomposition that may arise, however small the
quantity may be.

We have one other form of aquarium to consider, and that—
the garden pond—is certainly, in some respects, the best of all. It
may not be, and in fact 7s not, so well adapted for carrying out
close observations, especially in the case of the small creatures ; but
in it we can keep and rear a great variety of life under the most
natural conditions, and so maintain a ‘stock’ from which we can
always draw supplies for indoor aquaria when required, and from
which we may select objects for special study at all seasons of the
year.

For the study of aquatic plants, too, the garden pond is in every
way satisfactory. In it we can grow those species which require
much room, and those that will not flourish without plenty of soil.
Semi-aquatic plants may also be cultivated on its banks, as well
as the tall species which shoot high above the water and thus pro-
vide suitable resting places for certain aquatic insects when under-
going their final metamorphoses, and while they exist in the perfect
state.

The formation of a garden pond is not at all a difficult matter,
and the work entailed will afford some vigorous and_ healthy
exercise.

The size will of course depend on the space at disposal and the
amount of manual labour forthcoming; and, this matter being
settled, the first thing is to dig out the bed, to a depth of three or
four feet in the middle, with sloping banks.

The next thing is to make the bed impermeable to water, and
this may be done either by means of clay or cement.

If clay is used it should be free from stones, and it should be

86 THE COLLECTOR'S WORK

well worked or ‘ puddled’ till in a suitable condition for laying on
the bed. The puddling is a matter of great importance, for the
more thoroughly this is done the more impermeable will be the
bed.

Cement has the advantage of cleanliness. A bed of this material
can be thoroughly washed out when occasion requires, and the
layer of soil on it may be renewed as it becomes exhausted.

All the methods of aération employed in indoor aquaria may be
applied to outdoor or conservatory ponds, but nothing can possibly
be more effectual than the introduction of a suitable amount of
vegetable life. A fountain issuing from the summit of a central
rockery, relieved by the graceful fronds of ferns or the foliage and
flowers of semi-aquatic plants, will also add to the beauty of the
pond as well as to the air supply of its water.

But apart from the consideration of air supply there is little fear
of any but a very small pond becoming foul, for the surface exposed
to air is so large as a rule in proportion to the volume of the water,
that sufficient oxygen for the support of any reasonable amount
of animal life may be obtained almost exclusively by absorption
direct from the atmosphere.

It will hardly be necessary to inform the reader that, when the
water from a fountain jet is more than sufficient to make good the
loss by evaporation, it will be essential to have a properly con-
structed drain pipe to carry off the excess, and so prevent the banks
from becoming wet and marshy.

We will now give a little consideration to some of the species of
plants that are likely to prove useful to the aquarium keeper.

Among the best known of our pond plants are the pretty little
duckweeds (genus Lemna) that so often completely cover the
water with a bright green mantle. They are floating weeds,
requiring no soil of any kind, but deriving all their nourishment
from the water by means of long and slender roots. They increase
very rapidly by budding and also from seeds, but principally by
the former method. Their flowers are developed on the under side
of the frondlike leaves, and consist of a pistil and one or two
anthers, enclosed in a very small membranous sheath.

There are four British species of the genus, the smallest of
which—the Lesser Duckweed (Lemna minor)—is the one most
commonly seen on the standing pool. The Ivy-leaved Duckweed
(L. trisulea) is very much larger, but far less common. It is so

AQUARIA AND THEIR MANAGEMENT 87

named on account of its three-lobed fronds, which somewhat
resemble miniature ivy leaves in form.

These little plants are really valuable at times in the aquarium
or garden pond, particularly when the water is more or less exposed
to direct sunlight, for they serve to keep the
water cool, as well as to afford the darkened
shelter which so many aquatic creatures love;
but, being very prolific, it will often be found
necessary to keep them within bounds by ocea-
sionally skimming off the excess.

The American Pondweed (Anacharis Alsi-
nastrum) is another very useful plant, suitable
for aquaria and ponds of all sizes. It is a
Canadian plant, and was introduced into Britain
by some unknown means about the middle of
the present century. Its appearance in several parts of the country
was almost simultaneous, and from the time of its introduction it
has flourished so luxuriantly and extended so widely that many
streams and canals have been almost
completely blocked by it. This rapid
extension over so many districts remote
from each other has been, and still
is, a great puzzle to botanists. If
light fertile seeds which could be
carried here. and there by the winds
were developed by the plant, no further
explanation would be needed; but it
so happens that the weed is di@cious—
that is, the male and the female
flowers are borne on separate plants—
and the pistilliferous (female or pistil-
bearing) plants only have been found
in Britain. Hence it follows that the F1¢.62.—Tur American Ponp-
Anacharis must have been propagated pores tiene ea

; um)
entirely by buds.

It is a very hardy plant, and though it is attached to the soil
of streams and canals by roots, yet it seems to thrive equally well
in the aquarium without any soil at all, and a few fragments
simply thrown into the water in the summer time will soon pro-
duce a thick mass of branching stems thickly set with whorls of
small leaves, usually three in number.

Fic. 61.— Lemna
trisulca

88 THE COLLECTOR'S WORK

In the indoor aquariun Anacharis keeps beautifully green all
the year round, and it appears to be a splendid generator of oxygen.
It is also very valuable as a food for fishes, many of which are
very fond of nibbling away at the young
leaves. I have found it extremely useful
for maintaining a condition of purity in
small glasses or bottles where the smaller
species of aquatic animals are kept for
some time under close observation.

The Hornwort (Ceratophyllum de-
mersum) also is a valuable oxygen gene-
rator, and is extremely hardy as well,
and requires no soil. It is a floating
ieee en Hoan ook weed, deriving its nourishment, like the

(Ceratophyllum demer- ‘ackweeds, entirely from the water, and
sunt) is common in ponds and slow streams.
Its leaves are long and slender and
generally forked, and are arranged in whorls round the stem.

The flowers are very small and inconspicuous, the male and
female blooms being distinct. The former consists of a number
(about fifteen) of sessile anthers surrounded by a whorl of very small
bracts, and the latter of a small one-
seeded ovary similarly surrounded.

This plant—the only one of its
genus—is a very pretty ornament in
the aquarium.

Vallisneria spiralis (fig. 64) is a
most copious oxygen generator, and
on this account it has become very
popular among aquarium keepers.
This plant is not a native of Britain,
but is plentiful in many parts of
South Europe.

Its inconspicuous stem is peren-

ee nial, and bears a number of very long
hic. 64.—Vallisneria spiralis and narrow grasslike leaves.

The plant is diewcious, like Ana-
charis, and is remarkable for the manner in which the fertilisation
of the seeds is effected.

The female flowers have a cylindrical ovary, on the top of which
is a three-lobed calyx, and three large oval stigmas; and they are

——

AQUARIA AND THEIR MANAGEMENT 89

mounted on very long and slender stalks which are twisted into the
form of spirals, and which are so long that the flowers float on the
surface, the spiral lengthening as the water rises.

The male flowers are very small, and are mounted on short
stalks at the base of the plant. They are white, and in form
globular, and consist of one, two, or three stamens, surrounded by
a three-parted calyx.

When these flowers reach maturity they become detached and
rise to the surface. The calyx then expands, and they float about
among the female flowers, thus allowing the pollen grains to come
in contact with the stigmas.

The fertilisation having thus been effected, the spiral stalk con-
tracts till it is formed into a compact cylinder, pulling the female
flower to the bottom; and within the cylinder the seeds are
ripened.

The pretty Water Crowfoot (Ranunculus aquatilis) is deservedly
a favourite for the aquarium. Although almost always found in
water with a muddy bottom, yet it grows well.
in aquaria with no other soil than a layer of
sand.

The leaves of this plant are of two distinct
kinds, which we may term the submerged and
the floating. The former are really long narrow
tubes, arranged in such dense feathery clusters
and often growing so fast as to fill the pond or
tank with a tangled mass of green threads.

The floating leaves are broad and lobed, and .
lie horizontally on the surface.

The flowers are exceedingly pretty, and stand out of the water
on erect stalks. They are of a pure white colour, with a cluster of
many yellow stamens in the centre.

Sometimes the Water Crowfoot is to be seen in rather rapid
streams, but in this case it develops no flowers or floating leaves,
and is thus only a mass of waving green threads supported on long
and flexible stalks.

There are a number of aquatic plants, forming the genus Potamo-
geton, commonly known as Pondweeds. They are very pretty plants,
even though their flowers are green and inconspicuous, and they
are exceedingly useful as oxygen producers in the aquarium.

The members of this genus—more than a dozen in number—are
all fragile plants, sometimes floating on the surface, and sometimes

1G. 65.—Ranun-
culus aquatilis

90 THE COLLECTOR’S WORK

fixed to the soil by their roots; and representatives are to be seen
in almost every pond, large and small. In canals and sluggish
rivers, too, they sometimes flourish so profusely that the stream is

Fic. 66.—-Potamogeton natans Fra. 67.—Potamogeton densus

almost choked; and in the autumn, when they shed their leaves,
the quantity of vegetable matter carried into the sluices of mills
often causes much damage and delay.

The flowers have both stamens and pistil, and all the parts are
arranged in fours—the perianth four-cleft, four stamens, and four

seed-vessels.

Fic.68.—Potamo- Fie. 69.—Potamogeton Fic. 70.—TxHEr Lone-
geton perfoliatus crispus LEAVED PoONDWEED
(Potamogeton fluitans)

Perhaps the commonest species is the Broad-leaved Pondweed
(Potamogeton natans), the floating leaves of which are elliptical,
while the submerged leaves are long and narrow. Ponds and
portions of sluggish rivers may often be seen so densely covered
with the olive-tinted floating leaves of this weed that hardly a patch

of water is visible.
*

AQUARIA AND THEIR MANAGEMENT 91

Other species, such as the Close-leaved Pondweed (P. densus),
the Perfoliate Pondweed (P. perfoliatus), and the Curled Pondweed

Fic. 71.—TuHe Varrep- Fic.72.—TuHe Surmsmnc Fic. 73.—THE FUuar-

LEAVED PoNDWEED PonpwEED (Pota- STALKED Ponp-
(Potamogeton hete- mogeton lucens) WEED (Potamoge-
rophyllus) ton compressus)

(P. crispus), have no floating leaves. These, together with a few
other British species, are here figured.

oF \
Fic. 74.—TuHe FENNEL-LEAVED Ponp- Fie. 75.—TuHe SprAR-LEAVED
WEED (Potamogeton pectinatus) PonpwEEpD (Potamogeton

lanceolatus)

The Starwort (Callitriche verna) is a very pretty aquarium
plant. Its popular name has been given to it on account of the

*

92 THE COLLECTOR'S WORK

star-shaped clusters of leaves on the summits of the stems. The
flowers are usually unisexual. They are very small, green, and
situated in the axils of the leaves. The male flowers consist of a

Fic. 76.—Tue Grassy Ponpwerp Fic. 77.—THE WATER StTar-
(Potamogeton gramineus) wort (Callitriche verna)

single stamen between two bracts. The female flowers, which are
very similar in general appearance, have asix-lobed ovary with two
curved styles. |

The reader will probably meet with many other aquatic plants
during his excursions, and any of them may have a trial in the

Fic. 78.—THE Yettow Fic. 79.—Tur Waiter
Warer Liry (Nu- Water Liny (Nym- Frac (Acorus ca-
phar lutea) phea alba) lamus)

aquarium. Some there are that require plenty of soil, and when
these are chosen there should always be a moderately thick layer of
soil, under the sand or gravel, from which they may derive nourish-
nent.

Then, in addition to the British species, a number of foreign
plants (one of which has been already mentioned) have been imported

AQUARIA AND THEIR MANAGEMENT 95

by dealers in aquaria and aquatics, and some of these are deservedly
popular.

Again, we have many aquatic plants of such large size that they
are suitable only for large tanks and ponds. Foremost among these
are the beautiful Water Lilies.

The common Yellow Water Lily (Nuphar lutea) is to be found in
most parts of Britain. It is commonly known as the Brandy Bottle
on account of the peculiar spirituous perfume of its flowers. The
White Water Lily (Nymphea alba), also common in our lakes, is
interesting on account of its habits of closing its petals and drooping
its flowers at night.

A garden pond may be further ornamented by means of a selec-
tion of semi-aquatic flowering plants, though these are not of so

Fic. 81.—Tue Fiowerrnc Fic.82.—TurGreater Fic. 83. — _ Tue
Rusu (Butomus wmbel- WATER PLANTAIN LessER W ATER
latus) (Alisma Plantago) Prantatn (Alisma

ranunculoides)

much service in maintaining the supply of oxygen in the water.
Perhaps the best way of managing these, in the case of small
ponds, is to plant them in ordinary flower-pots, and then conceal
the pots in the midst of an artificial rockery so that they are par-
tially submerged. In this way the banks of an artificial pond may be
adorned with Sweet Flags, Flowering Rushes, Water Thyme, Arrow-
heads, Water Plantains, and many other really beautiful plants.
Now let us suppose the aquarium complete and well established.
Everything is going well. The animals are apparently living In

94 THE COLLECTOR'S WORK

the greatest of comfort. The measured and graceful movements of
the fishes show that all must be right. They give no evidence of a
lack of oxygen by gasping for air at the surface of the water. The
aquatic plants too, we suppose, are growing well. Their foliage is
beautifully green, and some are already showing flower.

With such favourable symptoms as these we may certainly
regard the affair as a complete success, but this must by no means
be taken as a guarantee that all will continue to go well, and that
the aquarium needs no further attention.

In fact the reverse is the case. Sooner or later your services
will be required to restore a balance of life. Some of your plants
will grow so wild and so profusely that the aquarium will bid fair
to become an almost impenetrable mass of entangled weeds. Duck-
weeds may increase so rapidly that nothing beside them is to be
seen. Green slimy freshwater sponges may form dense unsightly
floating masses. Occasionally a fish or other creature will die, and
the corpse, if not removed, will soon decompose and render the
water putrid.

With such possibilities as these, it behoves the aquarium keeper
to be always on the alert, especially in hot weather, when both
growth and decay proceed with great rapidity. _

It may not be amiss now to deal briefly with a few of the dis-
orders to which the aquarium and its inmates are liable, and to
consider the best means of restoring order and equilibrium.

One who keeps a bell aquarium after the ordinary fashion, with
no soil and no plants, must necessarily change the water at frequent
intervals in order to renew the air. In such a case, therefore,
stagnation is impossible, and fungoid and confervoid growths
stand no chance of a firm hold. The owner may claim this
advantage over another who endeavours to maintain the supply
of oxygen by the introduction of plant life ; but the latter would
hardly care to keep his aquarium in such an unnatural manner,
to say nothing of the loss of the picturesqueness afforded by
the beautiful aquatic plants, and the daily trouble, under a heavy
penalty, of emptying and refilling.

The aquarium that is once balanced by a proper adjustment of
animal and vegetable life may, and certainly does, require an
occasional overhauling, but the occasions are few and far between ;
and the warnings given to a careful observer are so gradual in their
appearance that he is never compelled to set about the task in haste
or at inconvenient times. If the aquarium begins to look turbid,

AQUARIA AND THEIR MANAGEMENT 95

or the conferve commence to settle on the glass, the owner knows
that, as a rule, a week or so may still run on with perfect safety
to the inmates; and the glass itself may be so thickly covered
with confervoid growths that nothing can be seen through it, and
even then the inmates be none the worse, but may be even better
off than when everything is perfectly clear and transparent.
On the other hand, the keeper of the unnatural bell aquarium is
compelled to change the water at frequent intervals; and a single
act of forgetfulness or a few hours’ pressure of business may cause
him the loss of his entire stock.

We have already stated that the spontaneous growth of low
forms of green vegetation is greatly accelerated by strong light, and
may therefore be retarded by subduing the rays by the interposition
of a screen of paper. If the vegetation is already dense, a temporary
darkness will reduce it. But this method of effecting a partial
cure is objectionable, for the light-loving creatures in the aquarium
are kept in darkness for a few days at least, and even then the
vegetable growth is not destroyed, but only stunted, and is ready to
develop with renewed vigour as soon as the vivifying light breaks
on it.

When the transparency of the aquarium is much impaired by
the growth of confervee, it will be as well to determine on a
thorough cleansing of the glass, and of course a change of water ;
‘and this may be done without the necessity of removing any of the
living things—animal or vegetable—save those which it is desired
to move.

Run out water with a siphon till only a few inches remain, and
then clean the glass with a little mop made by tying a pad of rag on
the end of a stick. If any of the deposit is so obstinate as to refuse
this kind of entreaty, dip the wet rag in very fine sand and apply
again.

In a minute or two the vegetable growth will be quite removed,
but the water remaining in it will be green and dirty. Start the
siphon again, and at the same time allow clean water to run in
from a can or pail, through another siphon of the same diameter.
In this way you get a constant stream through the aquarium, so
that, in a few minutes, if the siphon tubes are sufficiently large, all
traces of floating vegetable particles, together with the miscella-
neous sedimentary matter that always collects in an aquarium, are
effectually carried away. The aquarium is now refilled, and every-
thing is as bright and fresh as when it was first started.

Some of the freshwater univalve molluscs are greedy devourers

96 THE COLLECTOR’S WORK

of vegetables, and attack both the flowering plants and the low
forms. Of these the larger species of the genus Planorbis, especi-
ally P. corneus ; and Stagnalis, Pereger, Awricularva, and others
of the genus Limnea; also Paludina vivipara, have all been
recommended to aquarium keepers as a check on the growth of
plant life. .

Some of the above deliver their attacks principally on the
flowering plants, while others crawl over confervoid deposits,
devouring as they proceed. The former are of no very valuable
aid as scavengers, for even if the plants increase at too rapid a rate,
the excess can be easily removed; but those which attack the lower
forms certainly do a useful work. Nevertheless I believe the
value of these little window-cleaners has been much over-estimated.
Twenty or thirty of them in a small ten-gallon aquarium fail to
cope with the rapid development of conferve in hot weather, even
if the glass has a northern aspect. In fact, they seem to have buta
slight influence on the rapid growth of these minute plants.

We have now to deal with a much more serious growth, but
one which will never show itself except in the case of the most ex-
treme neglect. I refer to a growth of a fungoid nature, of a whitish
rather than a green colour, which attacks living fishes and other
creatures.

The presence of this form of plant life frequently denotes a
deficiency of light, and must always be regarded as a sign of the
presence of decomposing organic matter, and therefore is a proof
that the water is in a poisonous condition.

The aquarium gradually becomes turbid, just as if a little milk
had been thrown into the water; and fine white threads may be
seen radiating in patches on the surfaces of various objects, both
lifeless and living. A faint but unpleasant odour may also be
distinguished ; and, if deaths have not already occurred among the
inmates, heavy losses may be expected almost immediately unless
the sanitary condition of the aquarium is rendered satisfactory.

Now, before taking up the cure for this state of things, let us
inquire into the cause.

The fungoid growths to which I have alluded are the outcome
of an exuberance of decomposing nitrogenous organic matter, and
this may have been due to neglecting to remove the body of a dead
fish or other animal. Perhaps, however, a more common cause is
due to too much attention rather than neglect. It is a common
practice with amateurs to give the animals in an aquarium a great

AQUARIA AND THEIR MANAGEMENT 97

deal more food than is necessary for their immediate wants. Worms,
gentles, and other animals are thrown in rather thoughtlessly for
the newts, beetles, or fishes; and those which are not devoured soon
die, and then decomposition sets in.

Of course the warmer the water the more rapidly the decom-
position and the resulting contamination proceed; and hence the
necessity of being more watchful over the condition of aquaria in
summer than in winter.

Again, while considering those circumstances which tend to cause
such harmful conditions, 1t will be well to remember that certain
aquatic creatures feed on dead organic matter, and consequently
become most useful as scavengers.

Among the molluscs, Limnea pereger and the little animals
belonging to the genus Pisidium are very useful in this respect ;
and, all being of a very hardy nature, there need never be any diffi-
culty in maintaining an efficient scavenger corps to work for the
general welfare of the community.

Freshwater shrimps, which are generally abundant in small
streams, are also hardy lovers of high game, and to these may be
added the majority of aquatic beetles as well as young tadpoles ; but
it must be remembered that the former are very voracious creatures,
always ready to attack the unarmed and defenceless living as well
as the dead, and that the latter are highly appreciated by newts and
many of the fishes and aquatic insects.

But now. supposing that, notwithstanding our most careful
endeavours to prevent those conditions which lead to a general
putridity and its consequent fungoid growths, the aquarium reaches
_ this undesirable state, what remedy shall we apply ?

In considering this question we must remember that oxygen gas
is the great natural destroyer of dead nitrogenous organic matter.
An excess of this gas tends to decompose the unstable nitrogenous
compounds, converting them into simpler and less harmful sub-
stances which are readily absorbed by growing vegetation, and in
fact form valuable plant foods.

A constant stream of air or well-aérated water entering the
aquarium may therefore do much to improve the sanitary condition ;
but perhaps, after all, nothing is so safe as a complete change of the
water, produced either by emptying and refilling the vessel, or by a
prolonged circulation brought about by a continuous supply of fresh
water, with a waste pipe to prevent overflow.

I have just referred to temperature in relation to its effect in

H

98 THE COLLECTOR'S WORK

accelerating or retarding the decomposition of organic matter, but
there are other reasons for regarding temperature as a factor on
which success depends. On the one hand we must carefully avoid
excessive heat, for the warmer the water the less is its capacity for
dissolving gases and retaining them in solution ; and, seeing that
the gill-breathers are almost entirely dependent on the oxygen which
the water holds in solution, this becomes a very important con-
sideration. 3

On the other hand we have to avoid extreme cold; not that a
freezing temperature is likely to do any harm to those creatures
which in a. natural state survive the winter, but because the freez-
ing of a considerable volume of the water is likely to exert sufficient
expansive power to force out the sides of the aquarium.

I have often seen my fishes so entangled among plates of ice
running through the aquarium in all directions that they could not
move far for several days, and yet the return of a more genial
temperature showed that they had suffered little or nothing
through the temporary confinement.

I have also frequently seen frogs and newts, enticed from their
hiding-places by a spell of warm weather very early in the spring,
and afterwards overtaken by a severe frost, completely embedded in
a solid mass of ice for a week or more, with not the slightest power
of moving, and yet, on the melting of the ice, they seemed none
the worse.

Nevertheless such extremes should be avoided as much as
possible, not only for the comfort of the creatures concerned, but
to lessen the risk of damage to the vessel.

There is just one more matter for brief consideration—the
nature of the food required by our various pets. Some allusion
has already been made to these, so I will simply give a brief
summary with a few additions.

Fishes partake largely of certain pondweeds, particularly the
young buds and tender shoots of the plants to which I have already
referred. They should also be supplied, in strict moderation, with
very small earthworms, gentles (larve of the meat-fly), ‘ blood
worls ’ (not really worms, but the larve of a fly), caddis larve, and
‘ants’ eggs’ (not eggs, but the pup of ants).

l’rogs'and toads should be supplied with small beetles, worms,
caterpillars, &c.; and newts with earthworms.

The carnivorous insects will partake readily of all kinds of animal
matter; and tadpoles, molluses, and most other aquatic animals will
find all they require in an aquarium which is well supplied with weeds.

PA? Lt
LIFE IN PONDS AND STREAMS

CHAPTER VI
LOWER FORMS OF POND LIFE

HavinG now dealt with the practical portion of the pond-hunter’s
work, I shall devote the remainder of this work to a description
of some of the various species that may be met with during his
excursions.

In those cases where an important group of animals is repre-
sented in our ponds and streams by only a few species, I shall
describe all or nearly all of them. In many instances, however,
scores, and even hundreds of aquatic creatures are included in one
single order or family, and in dealing with such as these we shall
be obliged to confine our attention to a few typical species.

The lower forms of animal life are very well represented :in
stagnant and running waters, and the young naturalist who devotes
his attention to aquatic life will generally be able to find plenty of
these to occupy his attention when the more complicated forms are
scarce ; but he will not be in a position to study these lower forms
unless he is provided with a fairly good compound microscope.

This being the case, and seeing that it would be impossible to
treat at all fully of microscopic pond life in the small space at my
disposal, also considering the probability that many of my readers
may never possess a microscope suitable for the purpose, I shall
only select a few types of the lower divisions of animals, sufficient
to enable the reader to know and understand the general characters
of the larger groups, and thus to put him in a position to know what
he is examining, and to locate his specimens in their proper position
in the scale of life.

n 2

100 LIFE IN PONDS AND STREAMS

The Protozoa

The lowest forms of animal life are those which comprise the
sub-kingdom Protozoa. They are mere minute specks of a living
gelatinous substance called protoplasm, sometimes exhibiting no
trace of any variation in their structure, having no special organs
of any kind, not even so much as a covering without or a cavity
within. They possess not the slightest trace of a nervous system ;
but though. they have no organs of special sense, they may be
capable of experiencing general sensations.

If you examine a drop of water taken from a small stagnant and
muddy pool, you will probably find it teeming with microscopic
life, some forms moving about so actively that it is difficult to
keep them for any length of time within the field of the microscope
when a high power is being employed, and others creeping lazily
along on the surface of the glass slip.

Among the latter you may observe little gelatinous bodies of
variable form and size, perfectly clear and transparent around the
edges, but otherwise dotted with little granules of a darker
substance.

As you watch them you see portions of the body thrust forward,
first on one side and then on another. At first these projections
are perfectly clear, being formed by
extensions of the outer portion of
the body; but as each one becomes
longer, the granular substance sud-

; denly rushes into it. These pro-
ee Oa longations are temporary feet, which
MAGNIFIED 5 ,
are capable of being thrown out
from any part of the body, and by means of them the little animal
slowly drags itself along in a perfectly aimless manner, the direction
of its course being changed at almost every movement.

This little animal is called the Ameba, and is interesting as
belonging to the very simplest of all living beings; but although so
simple, it is a most interesting study for those who have a suffi-
ciently high magnifying power for the observation of its various
movements.

Sometimes we see within its body a number of little spaces filled
with water, and also a little cavity which contracts and dilates in

LOWER FORMS OF POND LIFE 101

such a manner as to suggest a function similar to that of the heart
of a higher animal ; but this cannot be the case, for the Ameaba has
no blood-vessels, and no blood to circulate.

Within its body we may also observe a round or oval mass of a
denser structure than the rest of the body. This is called the
nucleus, and occasionally we find more than one of these in the
same animal.

Like all other animals, the Amaba requires nourishment, for
not only does every movement imply a certain amount of waste
tissue that must be renewed, but it has also to propagate its kind.

But how can it feed, seeing that it has no mouth to receive food
and no stomach in which to digest it? This question can be readily
answered by observing the animal
under a high power.

The water in which it lives
always contains minute animal and
vegetable organisms, much smaller
even than the Ameba itself; and
these, and especially the vegetable organisms, constitute its food.

The Ame@ba has no power to make direct for its food, and
does not seem to be aware of its presence even when very near
it, but meets with it in an accidental kind of way during the course
of its erratic ramblings. When, however, it comes into actual
contact with a suitable morsel, it slowly surrounds it by means of
the temporary prolongations of its body.

The body of the Amwba being very transparent, the gradual
digestion of the morsel can be watched without difficulty ; and it is
interesting to note that the indigestible residue is cast out through a
temporary opening in any part of the body.

Amebe may be found in stagnant water at all times of the year,
though they are far more abundant during the warmer months. In
very cold weather they become very inactive, but resume their
movements on the approach of a more genial temperature.

Another interesting feature in the life history of the Amaba
is the manner in which it propagates its species. The nucleus
gradually elongates, becomes constricted in the middle, and then
divides. into two. The body itself then follows suit, and divides
completely with one of the two nuclei in each, thus forming two
distinct individuals, each of which proceeds on its own way.

It is not necessary to search ponds and ditches in order to find
Amebe, for they may be cultivated at home with the greatest of

Fic. 85.—Tun Amoeba Freep-
ING, THREE STAGES ILLUSTRATED

102 LIFE IN PONDS AND STREAMS

ease. Simply pour some boiling water on hay or other vegetable
matter, and allow the infusion thus formed to cool. Leave it out of
doors in an open vessel for a few days, and then remove a drop by
means of the dipping tube, transfer
it to a glass slip, cover with a cover
glass, and examine it under a high
power.

The infusion will be found to
be full of life, the result of the
rapid development of germs that
have been carried into the vessel.
by the movements of the atmo-
sphere, and the subsequent extremely rapid multiplication of the
beings produced.

Among the creatures thus provided with a home we may find
Ameba, but by far the larger number will consist of little beings
which exhibit the most lively movements, some darting and rolling
about in a most erratic manner, while others, though fixed to solid
objects or otherwise stationary, yet maintain a rapid motion of
parts of their bodies.

The animals to which we refer are generally known as Infuso-
rians, since they so readily make their appearance in infusions of
animal and vegetable substances; but they may also, like the
Ameba, be found in stagnant pools and ditches throughout the
whole of the year.

In many respects they resemble Amabe, being very simply
formed, consisting of a single gelatinous cell, and they also multiply
by division of their bodies.

Their bodies are provided with very minute hairlike projections,
sometimes arranged in definite lines on certain parts only, and
sometimes distributed equally or nearly so over the whole surface.

These little hairlike projections (called cilia) are kept in a rapid
vibratory movement, and the vibrations are frequently so rapid that
they are quite invisible. It is by this means that the Infusoria
move so quickly through the water, or, in the case of the fixed
species, keep up a rapid circulation of water round their bodies.

One of the commonest of the Infusoria is Parameciwm, com-
monly known as the Slipper Animalcule, from the slipper-like form
of its body. It is surrounded by a thin and somewhat firm struc-
ture that serves the purpose of a skin, and this gives rise to hundreds
of cilia scattered over its whole surface.

Fic. 86.—Ameba DIVIDING

A, before division ; B, dividing ; Cc, after
division

LOWER FORMS OF POND LIFE 103

The motion of this animalcule is very curious, being a combined
onward and revolving movement.

It has a funnel-shaped depression on one side of its body, and
the mouth of the funnel is richly supplied with cilia, the function
of which is to produce water currents that
will carry food particles into the depression.
This depression therefore serves the purpose
of a mouth; but the indigestible particles of
food are expelled in the same manner as with
the Ameba.

The different species of Paramecium
may be found in almost every pool during
the greater part of the year, even in the
depths of winter. Like many others of the
Infusoria, they seek shelter among the con-
fervoid growths; and if a little of this vege-
tation be taken home in a small bottle,
together with some water from the same F!6.87.—THE Sriprer

a rae Ese ANIMALCULE (Para-
pool, plenty of interesting microscopic work emia). Seat
will be forthcoming. They are very variable MAGNIFIED
in size, ranging from about one-hundredth
to one-thousandth of an inch in length.

As an example of the fixed Infusorians we will take the beautiful
Vorticelle or Bell Animalcules, of which several species are to be
found in ponds, sometimes in such numbers as to form a whitish
film over the fronds of the duckweed.

This animal is of the form of a minute wineglass, varying from
one-hundredth to one-, three-, or four-thousandth of an inchin length,
mounted on the top of a longer and exceedingly slender stalk.
The rim of the wineglass, or bell, as it is more commonly called, is
thickened and turned outward, and fringed with a circle of minute
cilia.

It is also provided with a cover which is capable of being lifted
like the lid of a box, and between the lid and the rim on one side
there is a funnel-shaped depression which runs to the middle of the
bell, and serves the purpose of a mouth and cesophagus.

As in Ameba, the outer part of the body is clear, while the
inner portion is dotted with little granules of a dark substance ; and
the nucleus, which is still more granulated, is elongated, and curved
into the form of a crescent.

In order to watch the movements of Vorticella, place one or two

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104 LIFE IN PONDS AND STREAMS

fronds of the duckweed to which they are attached in a live-box,
and, having found a cluster, watch them steadily under a moderate
power.

As you look at the cluster, observing the very rapid movement
of the vibratile cilia, and the floating particles that give evidence
of the water currents which the cilia produce, you notice now and
again that one of the animals very suddenly disappears; too sud-
denly, in fact, for its motion to be watched. But a little closer

ee

Fic. 88.—A Group or Vorticelle, Fic. 89.—A Srvete Vorticella,
MAGNIFIED AS SEEN UNDER A HIGHER POWER

attention reveals the Vorticella in its new position. Its stalk has
coiled up into a spiral with amazing rapidity, thus bringing the bell
close to the base of the stalk.

At the same time the rim has turned in so that the bell has
assumed a globular form, the lid has also been enclosed; and all the
cilia have disappeared.

Slowly it resumes its former position and activity. The stalk
gradually straightens out, the bell opens, the lid gapes, and the cilia
vibrate continuously.

So all the Vorticelle of the cluster go through the same perform-
ance in turn, even though undisturbed, as if a brief period of rest
were necessary at very short intervals. But now give a smart tap
on the table which supports the microscope, and the whole group
simultaneously retreat in the same manner as before.

There are several species of Vorticella to be found in our ponds.
Most of them are perfectly colourless, but others are tinted with

a

LOWER FORMS OF POND LIFE 105

green. All are so transparent that the process of digestion and the
rhythmic contraction of a vesicle can be seen distinctly.

Particles of food are carried into the mouth by means of water
currents set up by the cilia; and after the digestible matter has
been extracted, the insoluble refuse is cast out through a temporary
opening in the body.

We have seen that the Ameba multiplies by a simple division
of its substance. This is true also of Vorticella, which divides into
two by a longitudinal fission. Italso multiplies by means of germs,
which are formed by the breaking up of the crescentic nucleus, and
which are afterwards ejected into the water, provided with their
own means of locomotion.

Fic. 90.— Vorticella pivipING
LONGITUDINALLY

Sometimes a Vorticella may be seen to contract into a ball, and
to develop a firm gelatinous covering completely round itself. It
is then said to be eneysted, and in this state it passes a longer or
shorter period of perfect inactivity. But this is only a temporary
rest, and after a time the animal emerges again and resumes its
former condition and habits.

Some of the Infusoria have only one or two long whiplike cilia,
and these form a distinct division known as the Flagellata. One
of these, called Huglena, is often to be met with in stagnant water
and in infusions. It is particularly interesting on account of its
varied movements and almost constantly changing form, and per-
haps still more so on account of the controversies between zoologists
as to whether the being is an animal or a plant.

106 LIFE IN PONDS AND STREAMS

Tt contains green colouring matter, apparently identical with that
of plants; and the fact that it can move about is not sufficient in
itself to prove that it is not a plant, for motion and even locomotion
is not at allan uncommon phenomenon in both unicellular and
multicellular plants. But the nature of its food and the manner in
which it is taken seems to point to a place in the animal kingdom.

Plants possess the power of breaking up water, carbonic acid gas,
ammonia, and other inorganic fluids, and of building up complicated
organic compounds with their elements. Animals, on the other
hand, cannot subsist on such inorganic foods, but select their diet
from organic compounds that have already been built up in the
laboratory of some animal or plant; and if we are willing to accept
this feature as a satisfactory distinguishing characteristic between
the two great kingdoms into which living beings are divided, then
we must undoubtedly place Hwglena on the animal side, for it feeds
like Amaba and Vorticella, enclosing organic solids within itself,
and digesting them by the action of the fluids of its own body; but
on whichever side we place it, we are bound to admit that Huglena
is at least very near the borderland between animals and plants.

It is very interesting to watch the movements and habits of
Euglena. Both its body and its ‘tail’ or ‘whip’ are constantly
varying in form, the former becoming swollen first in one part and
then in another, and the latter
assuming all kinds of shapes, and
sometimes disappearing alto-
gether. At times the whole be-
comes quiescent, assuming a
globular form, and looking just
like a simple vegetable cell.

I shall briefly mention and
figure two other species, mainly
with the object of showing that
they include a variety of forms,
some of which are extremely
Fic. 92.—Actinophrys sol, HIGHLY beautiful objects when seen

MAGNIFIED under a good microscope.
The first of these is the Sun
Animaleule (Actinophrys sol), a globular species, with long tapering
cilia distributed over the whole of its surface, thus reminding us of
the glorious sun and his rays. It is to be found among the con-
fervoid growths in stagnant ponds and pools. The other is Stentor,

LOWER FORMS OF POND LIFE 107

a funnel-shaped animalcule, the largest of all the Infusorians, with
a wreath of cilia at the large end. The Sun Animalcule attaches
itself to pondweeds, but Stentor swims about actively, and has the
power of contracting its body into an oval
mass during its periods of rest.

Let us now leave the Animalcules—
representatives of the lowest sub-kingdom
of the animal world—and pass on to the
Polystomata or Sponges.

It may probably surprise some of my
readers to learn that sponges are to be
found in ponds and streams of fresh water.
The word ‘ sponge ’ recalls an image of the
common toilet sponge, which is really the
porous and fibrous skeleton of a marine
species, and it reminds us of diving and
dredging in warm seas. Nor is it gener-
ally known that we have sponges in plenty
on our own shores; but we must say
nothing of these, for we have to confine
our attention to two freshwater species— Fie. 93.—Stentor
the common River Sponge (Spongilla
Jlwiatilis), that covers the banks of rivers and canals, and forms a
greenish slimy crust on floating or submerged timber ; and the Pond
Sponge (S. lacustris), which may often be found in abundance in
ponds and lakes.

Sponges form the sub-kingdom Porifera, also known as the
Spongida and the Polystomata. The first of these names signifies
‘hole-bearing,’ and the last ‘ many openings’; and both serve to
denote the most important character of the group, for sponges
exhibit a number of holes on their surface.

The larger holes are the openings of canals which penetrate into
the sponge mass, and there they divide and subdivide, giving off
smaller and smaller branches, the smallest of which also open on
the surface. Thus the mass is provided with a complete system of
tubes for the circulation of water, which is always flowing in
through the small apertures of the living sponge and escaping
through the larger ones. The larger openings are usually situated
on the summit of slight conical projections, which give an irregular
appearance to the sponge mass and look somewhat like so many
little volcanoes.

108 LIFE IN PONDS AND STREAMS

The skeletons of sponges generally consist of a fibrous and horny
material, intermingled with which are little ‘ spicules ’ of silica that
have grown into all manner of curious shapes, often resembling
familiar objects, such as pins, axes, crosses, hooks, anchors, &e. In

some cases the entire skeleton

see is formed by spicules alone,
8 while in others there is a
AN framework of calcareous sub-
LA IN stance.

The animal itself consists

of a layer of cells which

completely cover the skeleton,
and may be compared to a
colony of Amebe. Many of
the cells, however, are pro-

vided with cilia, and it is by
the vibration of these cilia
that the water currents pre-
viously mentioned are produced. Each cell is thus supplied with
both air and food, the welfare of all being brought about by the
combined action of many individuals.

Sponges grow by an increase in the number of cells brought
about by a continuous budding ; and they are capable of multiplica-
tion in two or three ways. ‘They may be artificially increased by
cutting them in pieces, for each piece will develop into a full-sized
sponge; and the absence of individuality is so marked among
sponges, that whenever two or more happen to come together they
soon fuse into one so completely that they leave no trace of their
separate origin.

Sponges also give rise to buds, which are set free and eventually
start new colonies. Germs or eggs are also formed towards the end
of the summer, and develop early in the following year.

The River Sponge is common in the Thames and many other
British rivers, and may be found in enormous quantities attached
to the timberwork of locks and other structures both in rivers and
vanals. It is anything but pretty—until we examine it with the
microscope ; and no one unacquainted with it would suppose that
the dirty greenish or yellowish slime was a colony of living
beings.

But even though the animal is very unsightly, and, withal, often
discharges gases of a very unpleasant odour when disturbed, yet I

Fic. 94.—SPIcuLES FROM VARIOUS
SPONGES

va

LOWER FORMS OF POND LIFE 109

strongly recommend any one who possesses a microscope to take
home a small supply for examination as well as for general observa-
tion in the aquarium.

The Pond Sponge is very similar in character, but is of a dark
green colour, and is generally found in rounded or oval masses.

The spicules of both species may be easily obtained for micro-
scopic examination. If you allow a vessel containing a freshwater
sponge to remain exposed to air till the animal is dead and quite
decomposed, then the silicious spicules may be found among the
sediment at the bottom. Pour off the liquid, leaving the sediment
behind, and then fill up the vessel with fresh water. After allowing
a short time for the little heavy spicules to sink to the bottom, pour

‘off the water again, together with the lighter floating matter which

still remains suspended. Repeat this a few times, and the spicules
will have been freed from a large proportion of the miscellaneous
sediment.

Nitric acid (aqua fortis) may then be poured on the remainder.
This will destroy all the organic matter of the residue, as well as
limy and other substances, but will not attack the silicious spicules,
which will now form almost the entire sediment.

There will be no need to await the slow natural decomposition
of a sponge if the spicules are desired within a short time, for the
living sponge may be treated at once with aqua fortis, and the
necessary sediment obtained after no more time than is necessary
to perform a few careful washings.

We now pass on to a third sub-kingdom—the Calenterata—
which includes all sea anemones and corals. Nearly all the Cwlen-
terates are marine animals, but they are represented in our ponds
by the Hydra or Freshwater Polype, of which there are two species,
one commonly known as the Green Hydra (Hydra viridis) and
the other as the Brown Hydra (H. fusca).

These two species are so much alike, except in the matter of
colour, that the same description will answer for both; and
they are so common that no one need remain ignorant of their
structure and habits. Also, since the Hydra reaches a length of
from a quarter to half an inch, its interesting ways can be
studied to some extent with no further aid than an ordinary hand
lens.

When Hydras are required, a visit should be paid to a few ponds
or pools, no matter how small, where the surface of the water is
covered with duckweed. The only collecting apparatus necessary

110 LIFE IN PONDS AND STREAMS

is a few small bottles of about one ounce capacity and fitted with
good corks.

It would be well to number the bottles used and to make a note
of the particular pond or pool from which each is filled, such in-
formation being useful to guide one’s operations on a future occasion.

The bottles should be filled at the surface in such a manner as
to cause a quantity of the duckweed to flow in with the water, |
and may then be corked tightly and put into the pocket, for the
exclusion of air during a few hours will in no way affect the living
beings present.

On reaching home, the contents of each bottle should be poured
into a tumbler or other convenient glass vessel, which should then
be filled up with clean water
and placed on a shelf close to
a window that is not at the time
receiving the direct rays of the
sun.

After the glasses have re-
mained undisturbed for some
time, each one may be examined
separately for Hydras. Turn
the glass till the side which
previously faced the window is
now towards you, and then if
Hydra is present it will be seen
attached to the glass or the
under surface of the duckweed.

Its body is long, slender, and
transparent, and at the summit
there are several threadlike
tentacles, usually about six or
eight in number, spreading out
in all directions.

If either the tentacles or the body be touched, the former quickly
disappear within the latter, and the whole body shrinks up into a
rounded mass. But soon the creature slowly extends itself again,
and its tentacles may be seen gently swaying about in the water.

At the top of the body, in the middle of the crown from which
the tentacles radiate, is situated the mouth, on the summit of a
little conical projection; and this communicates with a cavity
within the body that serves the purpose of a stomach.

Fic. 95.—Tur Hypra, MAGNIFIED

LOWER FORMS OF POND LIFE 111

Should any small creature happen to strike against the tentacle
of a Hydra it is immediately seized and paralysed, so that escape
becomes hopeless. It is then drawn towards the mouth, all the
tentacles closing upon it, and finally lodged within the body cavity.

Here it is digested by the action of the fluids in the cavity, and
the nutritious portion is absorbed into the system, while the in-
digestible matter is cast out by means of the mouth.

At first the Hydra seems to have no means of locomotion, for it
remains fixed by the slightly widened base of its body for a long

time together. But we shall see it travel if we only wait its own

time. Sometimes it will simply detach itself from its position, and
then allow its body to float away wherever the movements of the
water carry it until a more suitable locality is reached, and then it
will attach itself again in the same way as before.

At other times it will hold on by means of its tentacles and
bring the hinder extremity of its body close to its ‘head,’ thus
drawing itself up into a loop. Then it will extend itself forward
and repeat the process, making headway by a series of strides much
after the manner of a ‘ geometer ’* caterpillar.

It is of no use to irritate the Hydra in order to compel it to move,
for, as we have already observed, this treatment simply causes it to
contract itself into a ball. The simplest way is to turn it from the
light, and sooner or later it will make for
the other side of the glass.

If Hydras are to be set aside for future
observations, it will be necessary to see
that they are provided with food; and the
simplest way to accomplish this is to
supply them with some pond water in
which small creatures such as cyclops
(p. 194) and water fleas (p. 193) abound.
This will enable you to watch not only the
hydra’s method of capturing and disposing
of its prey, but also to observe at least one
of its means of reproducing its kind.

At times you may notice one or more
small globular or pear-shaped prominences py4, 96,—'Tue Hypra
growing out of the side of its body. These WITH DEVELOPING Bup
are buds which will soon develop into
new individuals. Each one will gradually elongate, and then give
rise to tentacles like those of its parent; and finally it will become

112 LIFE IN PONDS AND STREAMS

detached and start an independent existence. And not infrequently
do we see other buds developing on the bodies of the young Hydras
before they are fully formed, so that there are three generations all
joined into one living mass!

This is not the only means by which the Hydra is capable of
reproducing its kind. It has been stated that when the creature is
cut in two each part becomes a complete animal, and it is possible
that this process of multiplication may take place naturally. And
this is not all, for during the warm summer months comparatively
large ovaries or egg cases may be seen near the base of the animal.
Each of these contains a large cell, which eventually divides up into
a number of smaller cells, and then, after developing a thick outer
case, becomes an egg, which detaches itself and gives rise to a new
Hydra.

Fic. 97.—HypRaA WITH Fic. 98.—TuHrreAD CELLS OF THE
Ovary HypRA, HIGHLY MAGNIFIED

Many of the foregoing observations may be carried on without
the assistance of any great magnifying power ; but if we remove a
Hydra from the water by means of a dipping tube and transfer it
to the live-box of a compound microscope, many other interesting
features may be observed. Thus we may see that the body wall
consists of two distinct layers of cells, that the walls of the tentacles
are a continuation of the body wall, and that the tentacles are
tubular throughout their length, and are really extensions of the
general body cavity.

Some of the outer cells of the tentacles are pear-shaped, and

LOWER FORMS OF POND LIFE 113

barbed at the narrow end. Within them there is also a coiled
thread. These are called ‘ thread cells,’ and it is by means of these
that the creature is enabled to paralyse its prey. The coiled threads
are capable of being thrust out very suddenly, so that they assist
in entangling the struggling victim, and probably also sting or
stupefy it. Similar cells are also found in the outer layer of the
body, but are not nearly so numerous as in the organs of pre-
hension.

After what has been said, it will be seen that the Hydra is really
a very simply formed creature. It has no complicated digestive,
apparatus, the general body cavity performing all the functions of
alimentation. Neither has it any special organ of respiration, but
receives the oxygen it requires direct from the water in which it
lives, the same being absorbed through its soft gelatinous body.
It has also no organs of excretion to carry off the waste from its
tissues, and it possesses no nervous system, though it has ‘nerve
cells’ by which it becomes cognisant of the world around it.

114 LIFE IN PONDS AND STREAMS

CHAPTER VII
WORMS, LEECHES, AND THEIR ALLIES

We have now to pass over an extensive sub-kingdom (Hchinoder-
mata) of marine animals, including the well-known Starfishes and
Sea Urchins, in order to study the worms, leeches, and other allied
creatures that inhabit our ponds and streams.

Before entering into details concerning individual species, I
shall note the principal characteristics of the sub-kingdom (Vermes)
to which they belong; and I strongly advise the reader to com-
pare my description as far as he can with his own observations on
one of the larger British members of the group, such as the common
Horse Leech or the Earthworm. He may not have the knowledge
and skill necessary to make an effectual study of the internal ana-
tomy of the specimen selected, but much may be learnt by means of
an examination of the exterior and a simple dissection.

For the latter purpose the dead animal should be pinned to a
sheet of weighted cork, and opened under water by means of a very
sharp knife or a fine-pointed pair of scissors. Such an examina-
tion will at least show that the creatures of this sub-kingdom are
far more highly organised than those which: we have previously
observed, even though some of them are so small as to require
the assistance of a microscope for detailed observation.

The Vermes are soft-bodied animals, and are generally long and
narrow. In many cases, as in earthworms and leeches, the body
consists of a number of segments, the divisions between which
are often visible from the outside as well as within.

The digestive tube generally runs throughout the entire length
of the body, and often contains a crop and a masticating gizzard.

Worms have no true heart, but they often possess a well-developed
system of blood-vessels, including some which are dilated and con-
tractile, and are thus capable of performing a function similar to

WORMS, LEECHES, AND THEIR ALLIES 115

that of the heart of higher animals, though less complicated in
character. The blood itself is sometimes coloured, but the colour
belongs to the fluid, and is not that of little floating corpuscles such
as exist in the blood of most of the vertebrate animals.

A nervous system is present in all but the lowest division of
this sub-kingdom, and it is often well developed, consisting of a few
ganglia or masses of nerve substance forming a ring round the food
passage near the mouth, and representing the brain of vertebrate
animals, and also of a single or double nerve cord extending back-
wards from these ganglia throughout the length of the body. These
nerve cords have swellings in each of the segments, and from them
nerves branch off right and left.

The lowest animals of this sub-kingdom are the Turbellarians—
a class of small flattened creatures that crawl about like slugs, or
swim by the aid of the cilia that fringe their bodies. Many of these
are marine, but there are several species to be found in ponds and
ditches, and some inhabit moist ground and mosses.

Some are so small that they might be mistaken for infusoria
when swimming by means of their cilia; but the microscope shows
that they are much more highly developed than the Protozoa.
They have a system of water-vessels, opening externally by little
pores; and the digestive canal is often disposed in such a manner
as to resemble a number of branches and twigs all radiating from a
central trunk. A double nerve ganglion is also visible near the
anterior end, as well as several nerves that radiate from it.

The largest of our freshwater Turbellarians are considerably
less than an inch in length, and they are generally so imperfectly
known that we are compelled to leave them with only a passing notice.

In small and putrid pools, especially where rapid decomposition
of organic matter is in progress,
we often find little threadlike
creatures called Nematoids or,
more commonly, Threadworms.
They are also to be met with in
exposed mud, among decaying
vegetation on. land, and in the Wra?O0.- A Nematoid
rotting wood of hollow trees.

Most of the species of this group (Nematoidea) are parasitic,
and more than one infest human beings; but some, which are
spoken of as the ‘ free Nematoids,’ subsist entirely on decomposing

matter.
12

116 LIFE IN PONDS AND STREAMS

There are few who have not seen the ‘ eels’ that are so often met
with in vinegar, and the little creatures known by the same popular
name that find their way into sour paste. These are typical ex-
amples of the free Nematovds, and will serve to give a general idea
of the group.

Some of our freshwater species are only a hundredth of an inch
in length, and the largest measure only about five-eighths of an inch.
They shelter themselves in mud, or hide among the vegetation of
various aquatic and semi-aquatic plants. Many are very sluggish,
and seldom attempt to swim unless disturbed ; but others are almost
incessantly wriggling their bodies in an undulatory fashion, some-
thing like that of the true eels.

It is an interesting fact that many of the Nematoids are capable
of developing only to a limited extent in freshwater pools and
streams, but that if they are taken into the digestive tube of a higher
animal they reach maturity within the body of their host, feeding
on its tissues, and finally laying their eggs within its body.

As a rule, however, such parasites never reach a stage that may
be termed wormlike until they enter their host’s body ; still it is
possible that many of the so-called ‘ free Nematoids’ that attain the
wormlike stage in water or mud are really parasitic when the favour-
able opportunity presents itself.

Tt may be mentioned too, in passing, that some Nematoids have
the remarkable power of existing for a long time in a dry condition ;
and even after having been dried to a dust with the aid of chemical
desiccators, they rapidly regain their vitality when moistened.

This feature will account for the unexpected appearance of worms
in vinegar, paste, and other fermenting substances in our houses, they
having developed from particles of living though dormant dust
which have been carried with the breeze.

Rotifers

Among the most interesting of the allies of worms are the little
creatures known as Rotifers, Rotatoria, or Wheel Animalcules,
which abound in stagnant water and sluggish streams.

The young student of natural history may not see why creatures
so small and so unlike the familiar earthworm should be placed in
the same sub-kingdom of the animal world; but it must be remem-
bered that naturalists are guided in their methods of classification
by features other than the mere external likeness of adult forms of
life, and the true relationship existing between different animals is

WORMS, LEECHES, AND THEIR ALLIES 117

sometimes made manifest only after carefully tracing their develop-
ment trom the very earliest to the mature stage.

If we thus trace the higher aquatic worms through their juvenile
days, we find that the young creatures are not at all like their
parents in general form and habits, but that they are active little
animals that swim freely in the water by means of minute vibratile
cilia, arranged in little circles round the edges of lobes or discs, and
therefore undergo remarkable metamorphoses before they assume
the form of the adult. These early stages to which we refer are
often spoken of as the larve, just as are the grubs and caterpillars
which ultimately develop into perfect insects.

Now the Rotifers very closely resemble the larve of these higher
worms. They are, as it were, worms which arrive at maturity and
become capable of reproducing their kind without the necessity of
metamorphoses, and without ever reaching the development attained
by their higher relatives. It must be observed, too, that the Rotifers
do not exhibit segmentation like the higher adult worms.

Some of the Rotifers are so large as to be distinctly visible to the
naked eye, but in all cases the microscope is necessary to make out
the details of their structure ; and their bodies are so transparent
that the whole of their internal anatomy is readily displayed by
transmitted light.

The lobes or dises which bear the cilia are very prominent, and
the little hairlike projections vibrate in such a manner as to give
the appearance of revolving wheels—a feature which will account
for the names by which they are known.

The largest species measure about a tenth of an inch in length,
while some are so small that five hundred placed in a line end to
end would only extend one inch. Some remain fixed to weeds and
other submerged objects by the flattened bases of their bodies, like
the Hydra; others attach themselves at intervals of rest by forcep-
like appendages at the ‘tail’; the remainder are free swimmers.

It is interesting to observe that the female Rotifers are much
more abundant than the males; and that while the latter have no
digestive tube, the former have a complicated digestive apparatus,
often including a powerful gizzard in which the food is crushed by the
action of hard structures on each other.

Like the Nematoids, Rotifers are capable of retaining life after
having been thoroughly dried, and are thus capable of being blown
about, and of resuming activity whenever they come in contact with
moisture.

118 LIFE IN PONDS AND STREAMS

Our first example is perhaps the commonest of all the Rotifers.
Its body is almost cylindrical, but tapering behind, and the head and
tail are both retractile. The head is furnished with two ciliated
dises, which give the appearance of re-
volving wheels when the little processes
are at work.

Let us place a little water containing
this Rotifer in the live-box, so that we
may watch its movements. It has ap-
parently resented our disturbance, for it
has retracted its tail and ciliated discs,
and assumed an almost globular form.

This period of rest is not prolonged,
however, for the body soon elongates
slowly, the telescopic tail is protruded, the
discs are also exposed, and the vibration
of the two circles of cilia is rapidly pro-
gressing.

Yet the little creature is undoubtedly
dissatisfied with its new quarters, for it
commences to crawl over the delicate
confervoid threads within the box. It
extends its body in the chosen direction,
fixes its head, draws its body into a loop
by bringing the tail forward, and then,

Fic. 100.—Rotifer holding on by the tail, repeats the move-
vulgaris ment, thus making progress like a looper
a, mouth; b, eyes; ¢, cilia; caterpillar, as we have already observed in

d, gizzard ; f, food canal ; the case of Hydra
k, developing embryos; J, Y ;

anus Then, not being content with the slow
progress thus made, it starts swimming,
keeping the wheels revolving rapidly as it goes.

Tinally it moors itself by its ‘foot,’ as the hinder extremity is
sometimes called; but its condition is not now one of absolute rest.
The cilia are still vibrating, producing vigorous whirlpools which
bring floating particles into the creature’s mouth.

While thus fixed we take the favourable opportunity of observing
the creature’s structure. We note the dark eye-spots just behind the
lip of the mouth, and trace the food passage through the transparent
body to its termination—the anus—near the tail. We mark the
food particles as they pass through the digestive canal, and observe

‘WORMS, LEECHES, AND THEIR ALLIES 119

_ the grinding action of the gizzard, and even distinguish the young
Rotifers developing within the body of the parent.

We figure a few others of this interesting class, the first of which
(fig. 101) is Floscularia cornuta or the Horned Floscule, which may
often be found among water plants. To these it remains permanently
fixed by the exceedingly thin and transparent case that surrounds

b=
. —\ > ©. ~~
x Ste yyy A
27> ee
‘

“Ss--

Fic. 101.—Floscularia cornuta Fic. 102.—Stephanoceros

and encloses the lower part of its body. The case is so very delicate
a structure that it is often difficult to render it visible without a
proper adjustment of the light.

The summit of the body has five short lobes, and each one of
these bears thirty or more very long and delicate cilia which, like
the case that surrounds the body, are hardly visible. There is also
a hornlike projection, but this bears no cilia.

Stephanoceros, or the Crown Animalcule, is a similar and equally
beautiful Rotifer. It is almost entirely enclosed in a delicate trans-
parent sheath, and its cilia are borne on five long radiating but

120 LIFE IN PONDS. AND STREAMS

retractile arms. Both this and the last species are easily visible to
the naked eye, but when out of the water the natural form is entirely
lost. When searching for them in the field fragments of weed should
be examined in bottles of water while being held up to the light.
Some Rotifers build tubes for the protection of their soft and
delicate bodies. One of the most remarkable of these is Melicerta,
which makes its tube of reddish pellets, formed within its body of
particles extracted from the water. This is also a fixed Rotifer, and

\\ L y :

a M1,
WN,
fl LL}

Z
z

Fic. 103.—-Melicerta Fic. 104.—Brachionus Fic. 105.—Dino-
urceolaris charis pocillum

has marked gregarious tendencies, large numbers being met with
on a single small leaf or patch of stem, their conical cases standing
out at right angles from the surface.

The whole body can be retracted within the tube, which is
about one twenty-fifth of an inch in length ; but when the animal is
disporting itself we observe four rounded lobes, two larger and two
smaller, the edges of which are fringed with minute cilia.

I conclude this short outline of the Rotifers by naming and
figuring two of the free-swimming kinds. These are the Pitcher
Rotifer (Brachionus wrceolaris), with one eye and a forked foot ;
and the Skeleton Rotifer (Dinocharis pocillum).

WORMS, LEECHES, AND THEIR ALLIES 121

The enthusiastic pond-hunter will meet with other species not
described ; but the foregoing remarks will suffice to give the reader
the general features of this interesting class, and to put him in a
position to commence his own observations and investigations of
the remarkable variety of form and habit which these creatures
exhibit.

Leeches (Hirudinea)

In almost every standing pond and sluggish stream we shall
meet with leeches, one species of which—the common Horse Leech
—is familiar to nearly all who take the slightest interest in the
varied forms of animal life.

When remarking on the general characters of Rotifers it was
found necessary to give reasons for placing these little creatures
in the same sub-kingdom as the worms, but no such precaution is
necessary in the present instance, for leeches are decidedly worm-
like in general appearance. Their bodies are soft and elongated,
and, like those of earthworms, composed of a large number of
segments which are often distinctly marked from without; and
where the segmentation is not apparent on the surface the divisions
are always clearly marked within.

AZ] Wite, whe o st

Fic. 106.—Tue Common Horst Leecu

The body of the leech is generally cylindrical or slightly flat-
tened, and tapering more or less both before and behind. At the

122 LIFE IN PONDS AND STREAMS

foremost extremity there is a circular sucking disc, by means of
which the animal can hold on firmly to solid objects, and the mouth
is generally situated in this disc. Some leeches have also a sucking
dise at the posterior extremity, and these
are thus enabled to progress somewhat rapidly
by alternately looping and extending their
bodies, again reminding us of the familiar
movements of the looper caterpillar.

The most effectual means of locomotion,
however, is swimming. The leech loosens
its hold, and immediately flattens its body
by the contraction of muscles which connect
the upper and lower integument, so that it
assumes a flat and ribbon-like form. Then
Prin ee Murcsiccs it executes a very graceful undulatory move-

a ment, thus propelling itself rapidly through
the water.

Some leeches derive their food by suction from the bodies of
vertebrate and other animals, and these are provided with horny,
toothed jaws by which they can inflict a wound of sufficient depth
to allow the blood to be drawn.

The digestive canal runs straight through the body, and gives off
a number of pouchlike extensions on each side.

The nervous system is composed of a number of ganglia, form-
ing, with their connecting nerves, a continuous double chain. The

QIN
— QOOD Rn

d
ART areca Tie
BZ SPS POI pw,
S : 4g a

Fic. 108.—Srcrion or Lrrcu, sHowING DIGESTIVE AND
Nervous Sysrems

m, mouth; d, digestive tube; a, anus; s, anal sucker; g, nerve ganglion

first pair of ganglia are much larger than the others, and represent
the brain in higher animals. The others are all arranged in pairs

one pair in each segment, close to the lower surface of the
body.
Even those leeches which live by sucking the blood of other
animals have blood-vessels of their own, for the fluid they imbibe
is not in quite a fit condition to directly nourish their own bodies,

WORMS, LEECHES, AND THEIR ALLIES 123

but has to be digested before it can build up their tissues. Thus
the leeches require a system of vessels to collect up the digested
matter, and to convey it in the form of the creatures’ own blood for
the nourishment of their tissues.

In each segment of the body of a leech there is an organ called
the segmental organ. These organs are really a series of water-
vessels, each of which opens by means of a tube at the side of its
segment.

The two leeches most generally known in this country are the
Horse Leech and the Medicinal Leech. The latter seems to have
been taken somewhat extensively from our own waters, particularly
in the south, but it is now seldom seen except in captivity, and
these captive leeches have been imported from the Continent, prin-
cipally from Austria and Sardinia. It is also very probable that

Fic. 109.—Tue Mepictnan Leecu

specimens of this leech taken in our own ponds are sometimes
escaped foreigners which have been imported for medicinal pur-
_poses. I have now two alive in anaquarium, that were taken from
the same pond on a common near London. Although I have dili-
gently searched this pond several times since the capture was made,
I have never taken another of the same species.

The Medicinal Leech (Hirudo medicinalis) is about three inches
long, but capable of extension to six or seven inches. It is of a
greenish colour, and may be readily known by the six interrupted
yellow bands which run longitudinally along its upper surface.

The Horse Leech is of about the seme size, coloured with a very
dark olive-green above and a lighter yellowish-green below. It does
not prey on vertebrate animals, except that it occasionally attacks
the frog, but derives its food by suction from such animals as worms,
soft-bodied larvw, and even its own kind. Its teeth are small, and

124 LIFE IN PONDS AND STREAMS

it has no power to inflict a wound except in the case of soft-bodied
creatures.

We have several other leeches, some very small and apparently
but little known; and others so transparent that all their internal
organs can be readily seen as they crawl about the sides of a glass
aquarium. Such observations, however, are sufficient to try one’s
patience, for these organs are best displayed only when the body of
the creature is fully extended at each stride, and it is rather tire-
some to have to follow it with a magnifier to make out the details
of its structure while it is apparently trying to cover as much
ground as possible in a given time.

Bryozoa

The Bryozoa or Moss Polypes are extremely abundant on all
our shores, but rather sparingly represented in fresh water.

The animals of this class were once grouped with the lowly
organised Hydrozoa or Jelly Fishes, to which they certainly bear
an external resemblance ; but it is now pretty generally agreed that
their relationships are rather with the worms.

Like many of the marine Hydrozoa, they live in colonies, all
the members of the same colony being joined together by a common
base, and hence they are frequently spoken of as the Polyzoa.

Each little polyp is surrounded by a membranous sac, at the
summit of which is the mouth, surrounded by several long, ciliated,
hollow tentacles, which, in our freshwater species, are generally
arranged on a U-shaped base.

Unlike the Hydrozoa, they have a fairly well-developed digestive
tube, consisting of an cesophagus, an enlargement which serves the
purpose of a stomach, and an intestine terminating in a vent or
anus.

This tube is bent on itself in such a manner that the anus is
very near the mouth, and a nerve ganglion is situated on one side
of it, within the bend.

The first portion of the digestive tube, together with the ten-
tacles, can be protracted or retracted at will, and thus the general
appearance of the polype is made to: vary very considerably at
different times.

One of the best known of our freshwater Bryozoa is Plumatella
repens—the commonest of its genus, which contains several species.

The whole colony is a branching structure, not very compact,

WORMS, LEECHES, AND THEIR ALLIES 125

but spreading on the under surfaces of floating weeds and of sub-
merged objects in very shallow water, much after the manner of
the stems of certain creeping plants.

Small apertures are visible at short intervals in this branching
structure, and, when quite undisturbed, the beautiful plumelike

Fie. 110.—Plumatella repens—Porrion or a CoLony

cluster of tentacles, sixty in number in each individual, may be
seen extended. But on the slightest disturbance the plumes are
quickly retracted, so that the chief beauty of the colony disappears.

Another species (Lophopws) is very different in general appear-
ance, for here the colony consists of only about a dozen individuals,
and these do not spread and branch, but all display themselves from
within an inverted oval gelatinous cup.

The longest diameter of the colony is often quite half an inch in
length ; but, although so large, no one unacquainted with the
Bryozoa would imagine for a moment that the shapeless mass of
jelly he observes on the under side of a floating leaf was a cluster of
such beautiful creatures.

Place the object in the live-box, however, and let it remain at
perfect rest for a time; and then the once shapeless mass assumes
the form of a delicate cup, and one by one the polypes extend them-
selves from their cylindrical sacs and display their beautiful
plumes.

Both this and the last named should be looked for towards the
end of summer, and even up to the time of late autumn. They are

126 LIFE IN PONDS AND STREAMS

exceedingly pretty objects for the microscope, and display, in addi-
tion to their plumes, the whole of their internal anatomy, for the
substance of their body is clear and transparent.

The reader is recommended to always find a place in his col-
lecting bottle for any leaves or stems that are found to be covered
with patches of transparent and shapeless jelly, or with a whitish
downy-looking or slimy substance. Such patches should always be
examined with a lens after the bottle has been at rest for a time,
and in this way he will probably make himself practically acquainted
with some of the most beautiful forms of aquatic life, the microscopic
examination. of which will well repay him.

It must be mentioned, in conclusion, that although most of our
Bryozoa remain fixed to one object, we have one, called Cristatella,
that moves freely at times—not the single individuals, but the whole
colony forming one moving mass. It is oval in form, flat on one
side and convex on the other, and usually half an inch or more in
length.

It sometimes remains quite stationary on the surface of a sub-
merged leaf or stem, using its flattened side as an adhesive dise or
foot; but when undisturbed it may be seen slowly creeping about,
displaying a number of clusters of tentacles all round the margin of
the colony.

127

CHAPTER VIII
FRESHWATER MOLLUSCS

A very brief outline of the more important distinguishing charac-
teristics of the sub-kingdom Mollusca was given in the first chapter,
in which it was also stated that the group is divided by naturalists
into three classes.

Two of these classes are very well represented in our ponds and
streams; and in order to make ourselves familiar with the general
stiucture of the two divisions, we shall select a typical representative
from each, and examine it with the aid of simple dissections.

The first example shall be the Freshwater Mussel (Anodonta)—
a type of the lowest class of the mollusca. The members of this
class have no distinct head, and are therefore often spoken of as the
Headless Molluses (Acephala). They are now more generally termed
the Lamellibranchs, and the class which they form the Lamelli-
branchiata. These names signify ‘ plate-gilled,’ and are applied on
account of the fact that the gills by which the animals breathe are
composed of thin membranous plates. They are also called Bivalves,
their outer shelly covering consisting of two ‘ valves ’ that move one
on the other in a manner to be presently described.

The student of pond life should procure one or two freshwater
mussels, and after a careful observation of their habits in the
aquarium, proceed to look into the details of their structure as far
as his ability permits.

Place the live animals in an aquarium, on a layer of fine sand.
For atime they will remain perfectly motionless, with their shells
tightly closed; but if left undisturbed, they will at last slowly open
the two shells and thrust out from between them a conical mass of
flesh which is called the ‘ foot.’ After a number of sluggish move-
ments they will succeed in completely burying the foot and placing

128 LIFE IN PONDS AND STREAMS

their shells on edge in an oblique position, with a portion of the
valves concealed beneath the surface of the sand.

The narrower or posterior end of the shell will now be seen to
gape a little, and two openings will be visible here in a membrane
which protrudes slightly beyond the margin. These openings are
called siphons, and are the means by which currents of water enter
and leave the body.

If now a solution of some harmless soluble colouring matter, such

4

Fic. 111.—Tue Fresuwarer Musset (Anodonta cygnea) AS SEEN IN
THE AQUARIUM

1, anterior end of shell; 2, foot ; 3, posterior end of shell ; 4, inhaling siphon ;
5, exhaling siphon

as cochineal, be passed gently to the neighbourhood of these chan-
nels through a fine glass tube, it will at once reveal two well-defined
currents of water, one passing into the body cavity of the mussel
through the larger and more posterior tube—the inhalent siphon—
and the other ejected through the erhalent siphon. The inhalent
siphon is surrounded by a number of little projections called ten-
tacles. These all project inwards, thus forming a kind of strainer
to prevent the entrance of large particles. It will be observed, too,

FRESHWATER MOLLUSCS 129

that the Anodonta does not remain fixed in one spot, but that it has
a decided power of locomotion ; and although its movements are
even slower than those of the proverbial tortoise, yet in time it will
cover a deal of ground, leaving its ‘ tracks’ in the form of shallow
grooves in the mud or sand that supports it.

There is some difficulty in keeping the Anodonta alive for a long
time in a small indoor aquarium, and this is due chiefly to the
nature of its food. It subsists
entirely on microscopic animals and
plants (chiefly infusoria and dt-
atoms) that are carried into its sys-
tem through the inhalent siphon, and
no ordinary indoor aquarium can
be expected to supply these in such
guantities as to support this large
bivalve. Frequent changes of water,
or even running water, if from the
household supply, will not improve
the condition, as, fortunately, our
drinking-water is not usually rich
in low forms of life. I have found
the Anodonta thrive best in still
water, without change of any kind,
either in a large glass aquarium F1. 112.—Postertor Exp or
or the garden pond, with plenty sane ae scenes piggicds 2a

THE INHALENT SIPHON WITH
of aquatic vegetation and a good irs TENTACLES (i.s.), AND THE
light; for it is under these circum- EXHALENT SIPHON (e.s.)
stances that we may expect a rapid
succession of microscopic beings such as the creature requires.

Now let us see what is to be learnt by a closer examination of
this lamellibranch. First we will inspect the exterior of the shell,
the animal alive or dead—it matters not which.

It will be observed that the two valves are united on what is
termed the dorsal burder by means of a very strong substance—the
ligament, which projects a little beyond the margin, close to the
hinge, or junction where the valves form a moveable joint. Both
valves are convex without, each forming a sort of very depressed
cone, the apex of which, called the wmbone, projects a little beyond
the dorsal edge.

The shell increases in thickness, as the animal grows, by additions
on the interior, and in area by the formation of new layers at the

K

130 LIFE IN PONDS AND STREAMS

edge. Hence the umbone répresents the first shell of the young
molluse, and the concentric curved ‘lines which are so distinctly
visible on the outside mark the margins of the shell at different

stages of growth. Thus we speak
of these lines as the lines of
growth.

For the further examination of
the shell we must look inside;
and if an empty specimen is not
ready at hand, the animal must
be killed for the purpose.

This may be done by immer-
sion in boiling water—the quickest
and most merciful method of kill-
ing a mollusc without injury to
the shell.

As soon as the animal is dead,
the valves gape considerably,
Fic. 113.—Suett or Anodonta being pulled open by the elasticity

cygned, SHOWING THE ligament of the ligament, which during life
(J) AND THE wmbones (Uw) is always maintained ‘on the
stretch’ by the contraction of two

strong muscular pillars passing from one valve to another.

These muscles are called the adductors ; and as the shell gapes
it will be seen that one is situated near the broader or anterior end
of the shell, and the other near the posterior end.

Pass a sharp knife between the valves, and cut through the ad-
ductors close to the shell. The elastic ligament is now quite un-
opposed, and the shell gapes more than before. Next remove the
animal completely from its calcareous house, and examine the
interior.

The hinge now appears as a ridge running along a portion of the
dorsal margin of each valve. This is the simplest kind of hinge
observable in the shells of molluscs. In some species this joint is
a far more complicated and even a beautiful structure ; and, since
the nature of the hinge is often a very valuable assistance in the
identification of bivalves, it will be well to depart for a moment
from the examination of our Anodonta in order to become ac-
quainted with the parts of a more perfect hinge and the terms by
which these parts are known and described.

There are often interlocking projections of various forms on

FRESHWATER MOLLUSCS ° 131

differenc portions of the hinge. These are called teeth, and are
named according to their position with regard to the umbone of the
valve on which they are situated. Those situated immediately
below the umbone are called cardinal teeth. Those in front of the
umbone—that is, on the side towards the anterior end of the valve
—are termed the anterior teeth, and those on the other side of the
umbone the posterior teeth.

Again, as the disposition of the teeth is not exactly the same on
both valves of the same species, it is absolutely necessary that, for
purposes of ‘description, each valve shall have its name. To this

Wh (bs

| \

MTT \\, WO
mL iy Ws
i \ \\ AN a > —

fe,
| AVA

:
eh
’ N

Fic. 114.—Inrerior Surrace or THE Lerr Vatve or Anodonta cygnea
Pp, pallial line; p.a, impression of the posterior adductor muscle; p.r, impression of

posterior retractor ; a.a, of anterior adductor ; a.r, of anterior retractor ; p.p, of the
protractor pedis muscle ; u, umbo ; /, ligament

end they are termed respectively right and left, and are to be dis-
tinguished from each other in this manner: Hold the closed shell
on its edge with the hinge uppermost and the narrow posterior
end towards you, and you have then the right and left valves turned
towards your right and left respectively.

Now to return to our Anodonta. When removing the animal
from its shell, we observe that the outer surface of the body is
attached to each valve along a line (pallial line) which runs almost
parallel with the lower or ventral margin, and extends throughout
the whole length of the shell; and after the soft structures have

K 2

132 LIFE IN PONDS AND STREAMS

all been removed, this line is distinctly visible on the inner pearly
surface of the valves, as are also the concentric lines of growth
previously mentioned as marking the exterior.

The interior surface of the shell is further marked by the im-
pressions of the various muscles that serve to move the valves and
the foot.

Near the posterior end, and bordered behind by the pallial line,
is the large scar that marks the attachment of the posterior
adductor muscle, which closes the valves by its contraction; and
immediately above it is the smaller impression of the posterior
retractor, which draws in the foot.

At the anterior end may be seen the impressions of the anterior
adductor muscle, which aids the corresponding posterior muscle in
closing the valves; also of the anterior retractor, which withdraws
the foot, and the protractor pedis, which assists in extending the
foot.

It is further interesting to note that all these muscular impres-
sions have faintly marked lines extending from their circumferences
towards the umbo, converging as they proceed. These lines enable
us to trace the various positions previously occupied by the re-
spective muscles as they advanced with the gradual growth of the
shell. ,

Before closing the inspection of the shell we will cut a small
furrow from the umbo to the ventral surface of one of the valves
with a small triangular file, and then break it across. If now we
smooth over the broken edge, and examine it with a magnifying
lens, we shall see that it is composed of three distinct layers. Outside
is a very thin horny layer, of a brownish colour, which covers the
entire outer surface and, bending round the ventral edge, extends a
little way over the inner surface. Next to this is a layer. composed
of prisms or pillars of carbonate of lime, standing out at right angles
to the surface. Lastly, we observe the inner pearly layer, composed
of thin layers of matter, some of which are calcareous and some
not, arranged alternately.

We have now to examine the soft structures of the animal itself.
For this purpose we shall find it advantageous to kill one of our
mussels either in a solution of mercuric chloride (corrosive subli-
mate), or by putting it into cold water, and heating gradually until
the valves open.

When the animal is treated in either of these ways, the form of
the body is not so much distorted nor the organs pushed so much

FRESHWATER MOLLUSCS 133

out of their natural positions by violent contractions of the muscles
of the foot as when killed by some other means.

Now insert a sharp knife between the valves, and cut through
the muscles on one side close to the surface of the shell; and then
cut through the ligament, and remove the upper valve, leaving the
animal attached by its muscles to the lower one. If this operation
be skilfully performed, nothing will be in the least damaged, with
the exception of the muscles above mentioned.

pl. ml. ft ee ee

Fic. 115.—Anodonta, LYING IN ONE VALVE, WITH Upper LOBE oF
THE MANTLE REMOVED

Pp, pericardium; k, kidney; p.r, posterior retractor muscle; p.a, posterior adductor
muscle ; a.a, anterior adductor muscle; a.r, anterior retractor muscle ; p.p, pro-
tractor pedis muscle; @, anus; ¢.s, exhalent siphon; i.s, inhalent siphon ; lm, cut
edge of the mantie; o.g, outer gill-plate; m.2, mantle lobe; v.g, inner gill-plate ;
v, internal organs ; f, foot; /.p, labial palps; /, liver

Lay the animal in a shallow dish or trough, with just sufficient
clean water to cover it, and then proceed to observe its structure.

The first thing that strikes the attention is the membrane which
forms thé covering of the body and lines the shell, extending nearly
to its ventral edge. This is the membrane to which we have al-
ready referred as being attached to the shell along the pallial line.
It is called the mantle, and the shell itself is formed by the secretive
power of the membrane.

134 LIFE IN PONDS AND STREAMS

If the upper half of the mantle be raised, and cut. off with a pair
of scissors without touching any other structures, the other parts of
the body will be displayed as in fig. 115.

Above are seen two large gill-plates extending throughout
almost the entire length of the body, and if these are lifted two
corresponding ones will be observed on the under side.

Towards the anterior end the gill-plates of either side are
separated by the foot and the mass of viscera or internal organs ;
but behind the two inner gill-plates are united, thus enclosing a
large cavity or chamber.

Fic. 116.—Srction or Anodonta, sHow1ina THE DicEstTivE TUBE

m, mouth; g, gullet; 7, liver; s, stomach; 7,7, intestine; a, anus; p, pericardium ;
k, kidney ; s.c, chamber above the gills

In front of the gills are two pairs of triangular flaps—the labial
palps, between which the mouth is situated.

Above the gills is the dark-coloured organ sometimes called the
kidney; and above this again, very near the ligament of the shell,
is the cavity termed the pericardium, within which may be seen the
heart.

Further, in front of the gills—that is, at the anterior end of these
organs—is the dark brown digestive gland, often called the liver ;

_. FRESHWATER MOLLUSCS 135

and within this lies the stomach, which communicates with the
mouth by means of the short gullet or esophagus.

Other structures may be revealed by means of simple but careful
dissections, conducted with the aid of a sharp knife, a pair of forceps,
and a pair of pointed scissors. Thus the three-chambered heart,
consisting of a thick-walled ventricle and two thin-walled auricles,
and the vessels which convey the colourless blood to and from it,
may be seen distinctly on opening the pericardium.

The digestive tube may also be traced throughout its length if
its course be carefully followed. The gullet and stomach have
already been mentioned ; and from the latter passes the intestine.
This tube is long and irregularly coiled within the body, passes
through the heart, and terminates at the posterior end of the body,
the extremity being termed the anus.

7 Cg
| Py
| |
(
J AtY)
I.
PY |
Og.
Fic. 117.—Tue Nervous Fic. 118.—TRansvERsE SECTION OF
System or Anodonta Anodonta
c.g, ganglia near the mouth ; p.g, gan- n, intestine; ve, ventricle of the heart ; 4,
glia of the foot ; 0.g, ganglia of the auricle; p, pericardium; s.c, chamber
posterior adductor above the gills ; v.c, the great vein ; u, tube

communicating with the kidney; 049,
outer gills; #.g, inner gills ; 4, coils of in-
testine ; f, foot ; m./, mantle lobe

The nervous system of Anodonta consists of three pairs of little
masses of nerve substance (ganglia) connected by and giving off
nerves. One pair is situated at the sides of the mouth, one pair in
the foot, and the other on the posterior adductor muscle,

136 LIFE IN PONDS AND STREAMS

There is, as has already been observed, no distinct head. Nor
are there any well-developed organs of sense. A sensitive membrane
supplied with nerves from the last pair of the above-named ganglia
is supposed to be connected with the sense of smell; and there is
a pair of little sacs, supplied with nerves from the ganglia of the
foot, which are regarded as auditory; but beyond these there are
no known organs of special sense.

Although I cannot here enter into details of the structure and
physiology of the freshwater mussel, there are one or two important
and interesting features concerning the circulation and respiration
that must not be overlooked; and for a better understanding of
these matters it will be necessary to study for a few moments a
transverse section of the animal.

Such a section is shown in fig. 118, and it gives a clear view af
the relative positions of certain of the cavities and tubes, as well as
of some of the solid structures.

The water which is taken into the inhalent siphon passes in part
through the gills, part into the mouth, and part through a space
between the gills and the body wall, and, as may be inferred, is
concerned both in the respiration and in the feeding of the animal.

These streams of water are urged onward by the incessant
vibration of minute hairlike projections (cilia) which are thickly
distributed on the surface of the labial palps, the gills, and the
interior of the mantle lobes; and they all find their way eventually
into a cavity situated above the gills, communicating with the
exhalent siphon.

That portion of the inhalent current which bathes the gills
brings the necessary supply of oxygen for the aération of the blood ;
the gas being held in solution by the water, and brought into such
close proximity to the thickly set network of thin-walled blood
capillaries of the gills, that absorption takes place very readily. At
the same time, carbonic acid gas—one of the waste products of
oxidation—passes from the blood into the water for removal.

The food of Anodonta consists of minute organisms, both animal
and vegetable, chiefly infusorians and diatoms, which exist abund-
antly in the water in which it lives. These organisms are obtained
of course from that portion of the inhalent current that enters the
mouth and passes through the alimentary canal.

It will thus be seen that the water currents which flow
through the system of Anodonta have important functions to

Ee ee ee eee

FRESHWATER MOLLUSCS 137

perform ; they convey the food, aérate the blood, and carry off waste
products.

Finally, let us briefly trace the Anodonta through the earlier
stages of its career.

During the autumn and winter the female may be found with
gills swollen much beyond their normal size. If at this season we
open the gills we find that the chambers between the lamine or
plates are quite full of eggs, with perhaps also a number of young
that have already hatched. These are so small that two or three
millions may be accommodated in the gill chambers of one single
individual.

The eggs are of course not formed in the gills, but in organs
(the ovaries) specially devoted to that function; and when the
little ova or eggs are developed, they pass out through openings in
those organs, and become lodged in the pouches of the gills.

When the young are hatched they bear no kind of resemblance
to their parent. Indeed so different are they, that at one time they
were regarded as parasites, and were named accordingly.

They certainly are bivalves, but the shells are triangular, and
are joined together by an elastic hinge which extends along one
side of the triangle. The opposite corners are curved inwards, and
are covered with little teeth, which are arranged in such a way
that they fit into one another when the two shells are brought
together.

The foot is only slightly developed, and from it there arises a
few long and slender filaments, forming what is called a byssus, and
corresponding with the hairlike tuft by which the marine mussel
attaches itself to the rock.

While these little creatures are lodged in the gill chambers of
the parent their byssi become entangled, and so by the aid of these
organs they are enabled to hold together and retain their positions.

At this stage, too, the mantle is very thin, and there is only one
musck to pull the valves together.

In the autumn or early winter the little larve are ejected by the
parent, and then they swim about freely, the motive power being
provided by the alternate opening and closing of the triangular
valves.’

Sooner or later each one comes in contact with a fish. It then
attaches itself by means of its curved valves, and not only does
it thus secure for itself a safe carrier while it undergoes its meta-

138 LIFE IN PONDS AND STREAMS

morphoses in a quiescent state, but the outer skin of its host
actually envelops it while these changes are proceeding.

At last the metamorphoses are over. The byssus is cast away,
the various internal organs have assumed the same form as those
of the adult, and the triangular shells with their one adductor muscle
are exchanged for new valves with two adductors.

The young mussel, now capable of looking after itseli—of moving
about from place to place, and of collecting its own food—allows
itself to drop from the host who has unwittingly provided it with
the aid it needed, and falls slowly to the mud at the bottom of
the pond, where it soon fixes itself by means of its foot, and takes
upon itself the habits of the adult.

THE SNAIL

We have now to take a type of the second class of the mollusca
—the Cephalophora or Head-bearing Molluscs. This class is divided
into three sections: The Scaphopoda, with a tubular shell, open at
both ends ; Pteropoda, which swim by finlike appendages attached
to the foot; and the Gasteropoda, which creep or swim by means
of a flattened foot.

The first of these divisions includes the so-called Elephant’s-
tooth Shell and other marine species. The second has no represen-
tative in our ponds and streams; but the third division will occupy
a considerable share of our attention.

The term Gasteropoda signifies belly-
footed, and the group is so named because
the creatures creep or swim by means of
the flattened lower surface of the body.

Some of the marine species have as
many as eight valves, and these roll them-
selves into the form of a ball when dis-

4 turbed, something after the manner of a

Fira. 119.—A WaTER SNAIL woodlouse; but the majority of species

EO ee) are enclosed in one shell, and are con-

SEEN WHEN CRAWLING ?

ON THE GLASS or an Sequently known as the wnivalve mol-
AQUARIUM luscs.

A good number of the univalve gas-
teropods have conical shells, many of which are not symmetrical.
They are known popularly as the limpets. Most of the others have
their shells coiled into a spiral, and are generally known as snails,

FRESHWATER MOLLUSCS 139

We have only two freshwater limpets, and all the other British
aquatic gasteropods come under the popular heading of Snails.

It may seem strange if, in this work devoted entirely to aquatic
life, we select a terrestrial snail as our type of the gasteropods. We
shall do so, nevertheless, chiefly as a matter of convenience to the
reader. The Common Snail (Helix aspersa) is so easily obtained
everywhere, and is of such convenient dimensions for examination
and dissection, that we can hardly do better than choose it for our
present purpose.

First let us observe the general outward appearance and habits
of the living animal.

The shell is conical in form, and consists of a spiral of about
four whorls or turns. The outer whorl is much larger than the

Fic. 120.—TnHe Common Snam (Helix aspersa)

others, and is therefore known as the body whorl; the other
three form the spire. If you hold the shell with the apex of its
spire turned towards you, and then trace a line in the direction of
the whorls, from the apex to the mouth, that line will form what is
termed a right-handed spiral, and consequently the shell itself is
described as right-handed or dertral.

Some of the snails have no spire at all, the whorls being wholly
or nearly so in the same plane, as in the well-known genus Planorbis.
Again, in some, as in the genus Physa, the spiral turns to the left,
and the shell is then spoken of as left-handed or sinistral.

The nucleus or apex of the cone is the oldest part of the shell,
and the whorls are all marked distinctly by lines of growth running

140 LIFE IN PONDS AND STREAMS

round them transversely, parallel with the rim (perzstome) around
the mouth, each one marking a former position of the aperture.

Tn addition to these lines, which really mark short intervals in
the life history of the snail, there will be observed on the body
whorl a few well-marked lines, often separating areas of different
depths of colour. These each distinguish one year’s growth from
that of another, and are frequently so well displayed that we are
enabled to form a fairly reliable estimate of the age of an old speci-
men.

The whorls of the shell turn round a central pillar called the
columella; and on the under surface of some snails, close to the
inner side of the peristome, may be seen an openinge—the wmbilicus,
which communicates with the cavity of the columella.

AN \ :

Fic. 121.—Sxrcrion or THE SHELL Fic. 122.—Suewu or Helix aspersa,
or A Snatw (Helix pomatia), sHow1na Mouri and PERISTOME
SHOWING THE HOLLOW COLUMELLA

Further, it will be observed that the peristome is not complete.
That is, it does not form a closed curve, completely surrounding the
mouth, the wall on the inner side being formed by the under con-
vex surface of the outer whorl.

When the snail is about to move, a considerable portion of its
body is protruded from its shell. It will be noticed that it is much
wrinkled, and covered with a soft and slimy skin. The head now
becomes distinctly visible, with its two pairs of tentacles, the upper
and longer of which bear the eyes. The mouth is on the under side.

The muscular mass behind the head is called the foot, and
the locomotion of the animal is accomplished by a succession of
wave-like contractions which travel rapidly along its flattened under

FRESHWATER MOLLUSCS 141

surface from behind forwards. It is very interesting to observe
these wavelike movements of the foot, and this may be done with
the greatest ease by simply placing a snail on a piece of clean glass
and then looking at the under surface of the foot through it.

If you lift the snail, and look at it from below while its foot is
still extended, you will see a portion of the edge of the mantle,
called the collar, and on the right side of this a rather large open-
ing—the pulmonary apertwre—which communicates with the
breathing organ. Also, close beside it, is a smaller aperture, which
is the anus, or outlet of the digestive tube.

Throughout the winter, and even during warm weather if the
creature fails to find food, it will hibernate, drawing itself com-
pletely within its shell, the mouth of which is for the time sealed
over with a film of slime (mweus), which soon hardens on exposure
to air. An orifice is left in this, however, for purposes of respira-
tion.

It is very interesting to observe the snail while feeding. Pro-
vide it with a leaf of any one of our edible vegetables, and it will
soon begin biting away at it in real earnest. Listen attentively
and you will hear, at short intervals, a half-biting and half-rasping
sound as each little semicircular piece is removed from the leaf.

Look at it from below as it eats the edge

of the leaf, and the nature of its mouth and OKI
the movements of its jaws will be easily dis- CHOGROIICY
cerned. Round the mouth will be seen soft COO
fleshy lips—one circular and surrounding the cal pi :
mouth, and two others, one at each side. CX Prt
On the upper side of the mouth is the GP OF OF eR

upper jaw or ‘ beak,’ which is really a horny SORA AR
plate with a sharp edge below. Opposite this hip ec: is
beak is a long and narrow slip of membrane Laaps, Vater
covered with many hundreds of minute sharp C

. . . V “u Vii
projections. The membrane is often called

the tongue; and the terms ‘lingual ribbon’ Fic. 123.—Porrion
and ‘ odontophore ’ are also applied. the ree
The teeth are so small that they cannot be SNAIL, MAGNIFIED ;
seen with the unaided eye, and even with a
hand lens appear only as so many delicate stripes, the stripes
representing the straight rows in which the teeth are arranged. A
compound microscope, however, readily shows up their real cha-
racter. They are little pointed masses of silicious matter, the

142 LIFE IN PONDS AND STREAMS

points being turned backwards towards the cesophagus. They are
arranged in regular rows, about one hundred and thirty in all, and
more than a hundred in each row, and their disposition on the
‘tongue’ is such as to remind one of an ordinary rasp.

The teeth are so hard that the snail has no difficulty in reducing
the toughest leaf or green stalk. In fact some of the marine
gasteropods even rasp through the thick ‘shells of other molluses
and feed on the inmates.

Only the front rows of teeth are brought into opposition with
the horny beak, and consequently only those are worn away. But
new teeth are continually being formed on the back part of the
membrane, and the membrane with its teeth is always being urged
forward by the new growth behind, thus bringing fresh rows of
teeth to the front to replace those that are worn down.

If you touch one of the snail’s tentacles while it is either feeding
or creeping, the tentacle willbe immediately drawn in. Watch this
movement carefully with the aid of a lens, and you will see that the
tentacle is pulled inside out, or rather outside in, just as you could

- pull the finger of a glove out-

“oS side in by means of a piece of
string passing through it and
fastened to the inner surface at
the tip.

This statement applies both
to the longer tentacles which
bear the eyes as well as to the
shorter ones, and hence it will
be understood that the eyes
themselves will be pulled to a
considerable distance within
the head when the longer ten-
tacles are retracted.

A dissection of the head of
the snail shows how the move-
ments are accomplished, for
it reveals four long and narrow
bands of muscular fibres pass-
ing from the muscular mass at
the base of the foot, and running each into one of the tentacles,
being joined, in the case of the shorter pair, to the inner surface of
the wall at the tip, and in the longer pair to the base of the eye.

Fic. 124.—Srcrion or THE Heap or
A Snaru (Helix aspersa)

/, tentacles ; n, nerves; m, muscles

7

FRESHWATER MOLLUSCS 145

The wall of the tentacle itself is composed in part of muscular
fibres which are arranged in circles round the tube—for it is in
reality a tube ; and the protrusion of the organ is brought about by
the contraction of these fibres.

A careful dissection of the head will reveal other interesting
structures. A large nerve ganglion will be observed at the back.
This is termed the cerebral ganglion, since it represents the brain
of vertebrate animals. From it four nerves pass forward into the
tentacles, two of them being the optic nerves or nerves of vision,
communicating with the eyes; and the others, belonging to the
short tentacles, possibly connected with some kind of special sensa-
tion in addition to that of touch.

In order to carry out the above or any other internal examina-
tion of the snail, the animal should be killed and extracted from the
shell. Perhaps the best way to accomplish the former, at least for
the present purpose, is to drown the snail in cold water, or to keep
it for a short time in water about twenty or thirty degrees above
blood heat. Boiling water would of course be far more effectual,
but it would cause an undue contraction of the muscles, and a con-
sequent displacement of some of the internalorgans. It also softens
some of the organs to such an extent that it is almost impossible to
examine them without their falling to pieces.

When the animal is quite dead seize the protruding portion of the
body between the finger and the thumb, and then, with a twisting
movement, extract the whole from the shell. During life the soft
body is held to the shell by muscles which attach it to the columella,
but these readily give way after a short immersion in hot water ; and
if about half of the shell be ground away in order to expose the
columella, fragments of the white tendons which gave attachment
to these muscles may be seen on the columella.

As soon as the body of the snail has been fully exposed, we
observe a marked contrast between the portion that is protruded
when the animal is crawling and that which remains permanently
lodged within the shell during life. The former is covered with a
thick wrinkled skin, while the latter is enclosed in a very thin
membrane—so thin and transparent that some of the internal
organs are distinctly visible beneath it.

This thin membrane is the mantle, which secretes the shell, and
which corresponds with the bilobed membrane, of the same name,
that lines the shells of lamellibranchs.

We have already mentioned the ‘collar’ of the snail, but its

144 LIFE IN PONDS AND STREAMS

true character is more easily seen when the animal is withdrawn
from its home. It is really the swollen edge of the mantle, and
forms the junction between this and the outer wrinkled covering.

The shell increases in size by the addition of new layers of
calcareous matter deposited on the lip, and this is always brought
about through the agency of the collar. Hence when the lip of
the shell is damaged it is repaired by this part. Further, the collar
contains the cells which hold the colouring matter that produces the
ground colour and pattern of the shell ; and consequently whenever
the margin of the shell is damaged the new matter added is always
uniform, both in ground tint and markings, with the original part.

The thin portion of the mantle also has the power of forming
shell, and by this means the shell is gradually increased in thickness
by additions inside as the animal grows older. It has, however, nc
pigment with which to colour what it forms. Hence if a portion
of either of the whorls be lost through external injury, although the
missing portion is replaced, the patch of new shell formed is either
white or colourless, and always remains thinner than the original
shell surrounding it.

There is a difference of opinion as to the exact manner in which
the shell is formed from the mantle. Some maintain that succes-
sive layers of the mantle itself are hardened by the deposition of
granules of carbonate of lime, and then detached to form the shell ;
while others look upon the process as one of excretion, believing
that layer after layer of membranous matter is thrown off by the
mantle, and these are afterwards hardened by the deposit of
caleareous grains which eventually almost entirely displace the
softer substance.

Whichever be the case, it is easy to prove that the shell consists
of membranous as well as of calcareous matter, for the former
may be dissolved out by means of a hot solution of caustic potash,
leaving the shell in a porous condition; or the latter may be dis-
solved in dilute hydrochloric acid, leaving a residue of delicate
membranous tissue in which the granules of calcareous substance
were deposited.

It is not necessary here to enter into the details of the structure
and physiology of the snail, such details being readily attainable
in numerous works on elementary biology to which the student
is recommended to refer; but I shall briefly note a few of the
more important points in its structure, most of which may be easily
made out by simple dissections. 'To carry out such dissections

FRESHWATER MOLLUSCS 145

the animal, after removal from its shell, should be secured to a
small sheet of weighted cork by means of a few pins, and then
covered with water in a shallow vessel of any kind.

A bristle may be passed through the pulmonary aperture into
the pulmonary cavity, the roof of which is formed by the mantle.
On opening this cavity a number of blood-vessels may be seen
thickly distributed on its walls; and it is here that the colourless
blood takes its supply of oxygen, and gives up carbonic acid gas to
be expelled with the expired air.

Projecting into this cavity may be seen the somewhat tongue-
shaped renal organ, an excretory organ which performs a function
similar to that performed by the kidney of higher animals.

Close beside this is the heart, which consists of two cavities, the
auricle and the ventricle. It receives the aérated blood from the
breathing organ, and pumps it through the vessels which convey it
to all parts of the body.

The digestive system may be traced by a careful dissection
commenced at the mouth. On the upper side of this is the horny
jaw or ‘beak’ already mentioned; and on the lower side of the
cavity beyond it, is the rounded mass which bears the lingual
ribbon.

A portion of this ribbon should be removed for examination
under the microscope, and then the dissection may be continued
along the wsophagus or gullet, which soon widens out to form the
crop.

At the sides of the crop are the large salivary glands, which
secrete a digestive fluid called the saliva. This fluid is conveyed
through narrow ducts into the cavity of the mouth, where it mingles
with the food, and gradually converts the starch into a kind of
sugar.

Beyond the crop the digestive tube becomes narrow again, but
it soon expands once more, forming the stomach. It then turns
sharply, narrows again, and forms the intestine, which terminates
at the anus—an opening which has already been mentioned as
situated in the collar, close beside the pulmonary aperture.

The intestine is not a straight tube, but describes an S-shaped
bend inside the digestive gland, part of which occupies the very
apex of the shell. This large gland prepares a digestive fluid
which is conveyed into the stomach, and has the power of dis-
solving food substances that are not changed by the saliva.

As regards the nervous system of the snail, we find no essential

L

146 LIFE IN PONDS AND STREAMS

differences between it and that of the anodonta. There are three
distinct masses of nerve substance. The largest of these ganglia
encircles the digestive tube just behind the cesophagus, and sends
nerves to the tentacles and other parts of the head. The other two
supply nerves to the mantle, the foot, and the various internal
organs.

Fic. 125.—ANATOMY OF THE SNAIL

to, tentacles bearing eyes; oe, esophagus; sn, nerve ganglion ; j, gizzard ; e, stomach ;
t, liver; f, bile ducts ; i, intestine; a, anus,; 7, kidney; vp, pulmonary vein ; p, pul-
monary organ ; c, heart.

There is yet much to be learnt concerning the sensory organs of
the snail. The eyes, we have seen, are situated at the tips of the
longer tentacles. The organs of sound are two small sacs which
lie close to the nerve ganglion of the foot. They contain a fluid,
in which float a large number of little particles of calcareous
substance that are set in motion by waves of sound. In this con-
dition they strike against the exceedingly fine nerve-endings that

FRESHWATER MOLLUSCS 147

lie in the walls of the sacs, and the impulse thus given travels
along nerve fibres which eventually reach the ganglion that
surrounds the digestive tube, causing the sensation of sound.

The shorter antennz are certainly very sensitive to touch, and
by some they are supposed to be the seat of the sensation of smell ;
but with regard to this, as well as to the sensation of taste, we have
no definite knowledge.

Having now briefly examined a type of each of the two great
divisions of the mollusca with which we are at present concerned,
we will proceed to notice some of the more important distinguishing
characteristics of our native freshwater species, chiefly with the
object of enabling the reader to identify the specimens that come
under his observation.

FRESHWATER BIVALVES

The British Lamellibranchs include representatives of three
families, and number fifteen species.

The three families are named respectively Spheriide, Unionidae,
Dreissenide.

Before looking into the details of structure by which we identify
the various species of these groups, it will be advisable to note
those broader features which are common to the members of each
family.

It must not be supposed for a moment that one who has the
power of naming shells at sight is necessarily well acquainted with
the natural history and structure of the objects named. The most
interesting and most instructive study for a naturalist is that of the
affinities and relationships of the various creatures that are brought
under his notice. It matters little, indeed, whether the names of
the species be known at all, but it is highly important that the
student should be able to give each creature, after examination, its
proper place in the scale of life.

Let us see, then, how we are to distinguish between the three
families of our freshwater lamellibranchs.

The Spheriida, in the first place, may be readily known by their
small size, the largest species measuring only a little over three-
quarters of an inch in length.

The shell is nearly spherical in form, and the hinge has both
cardinal and lateral teeth.

The mantle of the animal is open in front, and at the anterior

L2

148 LIFE IN PONDS AND STREAMS

end there are either one or two siphons. There are also two gill-
plates on each side, as we observed in the case of Anodonta, but in
the present family they are unequal.

The young are hatched in the cavity of the internal gills, and
only a few are accommodated by the parent at any one time.

The animals of this family are more active than the larger
bivalves, and particularly so while young. The foot is large in pro-
portion to the size of the animal, and is capable of considerable
extension.

It is interesting to watch the movements of these little molluses,
and this may be easily done by putting a few into a glass of water
with a tuft of pondweed.

At first the foot is thrust gradually forward. Of course this
organ becomes thinner and thinner as its length is increased; and
the extension is so great in the case of some of the smaller species
that the foot becomes two or three times the length of the shell,
and so thin and transparent that it is hardly visible.

The animal is now apparently inactive for a moment, but it is
really engaged in obtaining a good foothold ; and then follows the
contraction of the foot, which quickly pulls the shell quite up to the
point where its extremity was, for the time, fixed.

By a repetition of this mancuvre, the animal makes a series of
long strides; and it is surprising what ground it can cover within a
short time. It can climb the weeds with the greatest of ease,
and often makes its way quite to the surface of the water.

Its progress is probably assisted by the irregularities of the sur-
face on which it travels, these irregularities serving to give a
‘purchase’ to the foot; but it will be observed that these little
molluscs can move with apparently the same ease on a smooth and
polished surface. Thus they will at times creep up the glass of the
aquarium in which they are placed, even when the surface is per-
fectly clean and free from any vegetable deposit.

In this case it seems that the extremity of the foot must be held
by suction, and this appears more probable when the movements of
the creatures are observed through the glass by means of a magni-
fier, for the end of the foot then presents to the glass a small circular
flat surface, which reminds one of the sucking dises of the leech.

The British species of the Spheriid@e inhabit ponds, ditches,
and sluggish streams, and seem to thrive best on a muddy
bed. They are not found in rapid rivers; and, as far as my own
experience goes, they are seldom seen in ponds with clean sandy or

FRESHWATER MOLLUSCS 149

gravelly bottoms, even when extremely abundant in muddy pools
in the immediate neighbourhood. This of course is not neces-
sarily a proof of a mere mud-loving propensity, but may simply
show that the muddy bottom is capable of affording the food
which these small molluscs require.

Before passing on to a brief notice of the two other families
of our freshwater bivalves, a digression may well be made for
a short time in order to say a few words on the interesting subject
of migration.

An excavation is, we will suppose, made in a certain locality ;
and this, filled with rain and water from the drainage, becomes a
permanent pond.

As soon as the water begins to collect, pond life of various kinds
makes its appearance. Here are numerous microscopic forms,
aquatic insects, batrachians, and, after a time, even molluscs!
Now, it is easy to account for the appearance of the greater pro-
portion of this new population. The microscopic forms are easily
carried considerable distances by wind. Winged insects travel over
great distances from one pond to another, and deposit their ova on
weeds, or on the surface of the water itself. Frogs, toads, and
newts, too, are famous nocturnal travellers, and may often be seen
considerable distances from the nearest piece of water. But how
shall we account for the migration of molluses, and especially the
less active bivalves? These all breathe by gills, and the gills are not
capable of absorbing the necessary oxygen unless surrounded by
fluid. They can certainly live for a long time out of water, but not
under the influence of a bright sun; and when they are left on dry
land through the drainage or evaporation of the water in which
they lived, instead of proceeding apace in search of a new pond or
stream, they shrink within their shells, as if to conserve their small
store of moisture till the water reaches them again.

Thus we often find, after an unusually dry season, hundreds and
hundreds of dead molluscs, baked by the burning sun, lying on the
parched and cracked ground which now surrounds a little puddle—
the only remains of what was, a few weeks before, a comparatively
large pond,

How, then, shall we account for the appearance of molluses in
a new pond, a mile or more perhaps from the nearest pond or
stream ?

Here is at least a part of the solution to the problem. Wading
birds, which obtain their food from marshes and the banks of ponds

150 LIFE IN PONDS AND STREAMS

and rivers, have been found, when shot, to have a bivalve shell
attached to one of the claws. The explanation is simple. The
bird, while wading in the mud in search of food, happened to thrust
one of its claws between the gaping valves of a molluse. Under
these circumstances, the mollusc would of course close its valves
with all its might on the intruder.

The sequel to this is plain. The bird presently takes to flight,
carrying the bivalve to some other piece of water, perhaps many
miles away, and thus possibly conveying a species to a new
locality.

I have reason to believe, too, that batrachians may do much
towards the distribution of bivalves, and in a similar manner; for
while pond hunting I have captured several frogs and toads with
bivalves (Spheriwm corneum) clinging firmly to their toes.

Some small ponds and ditches are particularly rich in this
species of the bivalves ; and it is also interesting to note that many
of the frogs which are captured in the neighbourhood of these have
imperfect toes—toes which evidently have been bitten or clipped
in some way or another. And when one remembers the power of
the adductor muscles which close the bivalve shells, also the
sharpness of the edges of the valves, and the persevering tenacity
with which a bivalve will hold on to an intruder who happens,
accidentally or otherwise, to encroach within its domain, it seems
highly probable that the missing portions of the frogs’ toes have
become the property of bivalves which may, in some instances
at least, have been transported a considerable distance by the
unwilling carrier.

The second family of our freshwater bivalves is termed the
Unionidae. It includes only five native species, all of which attain
considerable dimensions. 'The smallest of them exceeds two inches
in breadth, while the largest often reaches eight or nine inches.

The shell is oval or elongated. The valves are equal, but not
equilateral. In some species the teeth, both cardinal and lateral,
are strongly developed; but in others are entirely wanting. The
ligament is external, and very conspicuous ; and the muscular im-
pressions are very distinct. These latter include the impressions
of the adductor muscles—anterior and posterior—also of two pedal
muscles at the anterior and one at the posterior end of the shell.

The edges of the mantle are quite free except at the posterior
end, where they unite to form the two siphons.

The members of this family are found chiefly in ponds, lakes,

LLATE I.

Danielsson & Co. ‘

London, del. ad. Nat, et Chromolith.

FRESHWATER MOLLUSCS 151

and sluggish and muddy streams; but one (Unio Margaritéfer)
inhabits rapid rivers and mountain torrents.

The third family (Dretssenid@) has only one British represen-
tative. Its shell is somewhat mussel-shaped, but very decidedly
triangular. The umbones are at the extreme end of the shell, and
the valves are bluntly keeled in such a manner as to give the shell
the appearance of a small wide boat.

The animal differs from those of the two preceding families in
that the mantle is closed with the exception of a small orifice through
which a byssus (page 137) protrudes.

The following table shows at a glance the chief distinguishing
features of the three families just alluded to, and will materially
assist the reader when grouping his specimens :

Order Lamellibranchiata

Gills leaflike, two on each side, between the body and the
mantle.

1. Shell small and almost globular. Hinge with both cardinal
and lateral teeth. Body with either one or two siphons at
the anterior end. Mantle open. Family SPH RIIDA.

2. Shell large, oval or elongated. Hinge with or without
teeth. Body with two siphons at the posterior end. Mantle
open. Family UNIONIDS.

3. Shell boat-shaped. Umbones at extreme end. Valves
bluntly keeled. Teeth small or absent. Mantle closed.
Animal provided with a byssus. Family DREISSENID4A8.

Family SPHARITDA

We will now note the chief characters of the individual species
of each of the three families of bivalves, commencing with the
Spheriide.

In the first place, however, it must be observed that the British
members of this family are divided into two genera, named respec-
tively Spheriwm and Pisidiwm. The shells of the former genus
are equilateral or nearly so, the hinge being at or very near the
middle of the dorsal border. There are two small cardinal teeth in
the right valve, and one in the left. The lateral teeth are elongated,
and number one on each side in the right valve, and two on each
side in the left. The animal has two siphons at the anterior end,
and the outer gills are smaller than the inner.

152 LIFE IN PONDS AND STREAMS

In Pistdiwm the shell is not equilateral, the anterior side being
longer than the posterior. The teeth are the same as in Spheriwm,
but are more strongly developed in proportion to the size of the
shell. The animal has only one (exhalent) siphon.

Perhaps the commonest and most
widely distributed species of the Spheriwm
genus is S. corneum, which may be dredged
out of ponds, ditches, and sluggish streams
almost everywhere, and is so abundant in

corneum some places that scores may be obtained at
. a single haul.

The shell is of a brownish colour, finely grooved along the lines
of growth, and often prettily banded with a darker or a lighter
colour. The length of the full-grown specimen is about half an
inch, the width nearly five-twelfths of an inch, and the thickness
one-third of an inch. The umbones are very blunt, and the ligament
is hardly visible from the outside.

The young of this species are very different from the adult in
form, and may be easily mistaken by the inexperienced shell-
collector for a different species. They are not nearly so thick and
spherical as the adult, and the umbones are not so prominent.

The largest species of the genus is S. rivicola (Plate II, fig. 1),
which measures more than three-quarters of an inch in length. In
general form it resembles the last species, but is not quite so swollen ;
and its shell, which varies in colour from a pale yellow to a rich
olive-green, is often conspicuously marked by bold dark bands. It
is more deeply grooved along the lines of growth than Cornewm,
and its ligament is distinctly visible from the outside. This species
may be found in sluggish and muddy streams, but is not nearly
so widely distributed as the preceding. Its chief haunts are the
slow rivers and the canals of the south of England. It is less
abundant in the north, and does not seem
to have been met with in Wales, Scotland,
or Ireland.

The third species—S. ovale—is much
more local; and, although moderately
common in ponds and ditches in the neigh-
bourhood of London, it has been taken in only a few of our
counties, and not at all in Wales, Scotland, and Ireland.

Its shell is oblong, of about the same length as that of S. cor-
neum, but not nearly so swollen. The umbones are small; the

Fic. 127.—Spherium
ovale

FRESHWATER MOLLUSCS 153

ligament very narrow, but visible on the exterior ; and the lines of
growth are very finely grooved. The colour is very pale grey, often
yellowish or brownish.

The last species of the genus is S. lacustre, which is widely dis-
tributed in the English counties, though not known in Scotland or
Ireland. It is the smallest of the four, being
only about a third of an inch in length, and is, @ = ‘\y
like the last species, more compressed than =

Fic. 128.— Sphe-
rium lacustre

Corneum and Rivicola.

The colour is very pale yellowish grey; and,
as will be observed by the illustration, the
general form is somewhat squarish or rhomboidal, with narrow
and prominent umbones. The shell is finely striated, and the
nucleus covers the umbones as with a small whitish cap.

The next genus (Pisidiwm) includes five small species, the
largest of which does not exceed S. lacustre in size.

They are readily distinguished from the preceding by their un-
symmetrical form, the umbones being considerably removed from the
middle line, and the anterior side longer than the posterior. The
animals also have only one siphon, viz. that for the exhalent
current.

The largest species of this genus (P. amnicum) has a triangular
brownish or grey shell, with blunt umbones, and rather deep
grooves along the lines of growth. The teeth
resemble those of the genus Spheriwm, but are
more strongly developed in proportion to the Q ®
size of the shell; and the length of the full-
grown shell is only one-third of an inch. The Fie. 129.—Pisi
ligament is short and narrow, but is very dis- ““™“™ anuvicum
tinctly visible from the outside.

Taking the species in order of size, the next is P. fontinale, which
measures hardly one-fifth
of an inch in length. It
is more swollen than Am-
nicum, and the shell is
not so coarsely grooved.
The ‘umbones, too, are Fic. 130.—Pisidiwm fontinale, ENLARGED

narrower and more pro-

minent. Pusillwm, the next species, is less than one-sixth of an
inch in length, and the shell is oval rather than triangular;
neither is it so unsymmetrical as the two preceding species, for the

154 LIFE IN PONDS AND STREAMS

umbones, which are blunt and short, are nearly in the middle of
the dorsal margin.

The two remaining species (P. nitidum and P. rosewm) are
very small, being only
one-tenth of an inch in
length. Both are found

& in ponds and_ ditches,
often in each other’s com-
Fig. 131.—Pisidiwm pusillwm, ENLARGED pany, and it is hardly
possible for one to dis-

tinguish between them without the aid of a lens.

When carefully examined, however, it will be observed that

Roseum is oblong-in form, while Nittidum is more globular. The
shell of the latter, too, is smooth and shining, and is thickest near

Fic. 132.— Pisidiuwm nitidum, Fic. 133.—Pisidiwm roseum,
ENLARGED ENLARGED

the dorsal margin; but the former is deeply grooved, with rather
prominent umbones which are so far out of the centre that the
anterior portion of the shell is much longer than the posterior.

As a further aid to the identification of these five small shells it
may be mentioned that the ligament of the shell is conspicuous only
in Amnicum, and quite invisible from the exterior in Nitidwm and
Pusillum.

The following table will assist the reader in naming his speci-
mens of the Spheriide family, but he must be prepared to meet
with variations in most of the species, the nature of which there is
not space to describe.

Family SPHARITDA

I. Genus SpHarium.—Shell equilateral or nearly so. Animal
with two siphons.
(a) Shell brownish or yellowish ; swollen in middle. Umbones
blunt.
1. Finely grooved. Ligament invisible from exterior.
Length half an inch. S. corneum.

FRESHWATER MOLLUSCS 155

2. Strongly grooved. Ligament conspicuous. Length
three-quarters of an inch. S. rivicola.
b) Shell whitish or greyish; compressed. Umbones small.
8. Oblong; finely grooved. Ligament visible externally.
Length half an inch. S. ovale.
4. Squarish. Umbones narrow, prominent, and capped.
Ligament hardly visible. Length one-third of an inch.
S. lacustre.
II. Genus Pistp1um.—Shell inequilateral. Animal with one
siphon.
(a) Shell triangular; swollen.
1. Strongly grooved. Umbones blunt. Ligament con-
spicuous. Length one-thirdof aninch. P. amnicum.
2. Finely grooved. Umbones pointed. Length one-fifth
of an inch. P. fontinale.
(b) Shell finely grooved. Ligament not visible externally.
3. Shell oval. Umbones blunt and almost central.
Length one-sixth of an inch. P. pustllum.
4. Shell roundish, shining. Dorsal part swollen. Length
one-tenth of an inch. P. nitidum.
(c) Shell oblong; strongly grooved, swollen in middle.
Length one-twelfth of an inch. P. roseum.

When describing the Freshwater Mussel (Anodonta) as a type
of the bivalyes, in the early pages of this chapter, we referred to the
remarkable prolificacy of this animal, which is capable of pro-
ducing, and accommodating within its gills hundreds of thousands
of its young. These young, it will be remembered, leave the
body of the parent while still very minute, and make use of the
locomotive power of a larger animal, by attaching themselves to it,
until they are able to start a career for themselves.

It is very different, however, with the Spheriide. In this
family the number of young within the parent seldom exceeds
twenty at any one time; and, instead of leaving the body of the
parent at an early stage, they often claim maternal protection till
they have attained quite a quarter of their full length.

Family UNIONIDAi

We have already become somewhat familiarised with this family
by our brief examination of one of its members—Anodonta.
The term Unionide is derived from unio, which signifies ‘a

156 LIFE IN PONDS AND STREAMS

pearl,’ and is supplied on account of the formation of pearly or
nacreous matter, both in the shells, and also in the soft structures
of the animals forming the group.

The shell really consists of three layers, the structure of
which may be seen by examining a vertical section under the
microscope.

The outer layer is thin, and is composed of a horny substance.

The middle one is comparatively thick, and consists of a number
of small polygonal columns or prisms, all arranged parallel with
one another, at right angles to the surface of the shell, and con-
nected by inward extensions of the outer horny covering. This
layer is generally spoken of as the prismatic layer.

The inner layer is composed of nacreous substance which, when
polished, is termed ‘ mother of pearl.’

The nacreous matter is formed by alternate layers of calcium
carbonate (also called carbonate of lime) and animal’ substance,
both in the form of exceedingly thin lamine; and the peculiar
pearly lustre of the shell is partly due to this structural arrange-
ment. If, however, a thin section of the nacre be examined, it will
be found that the thin layers above mentioned are minutely waved
or undulated, and this fact has undoubtedly much to do with the
production of the pearly lustre.

If a nacreous shell, or a piece of the nacreous layer of a shell, be
steeped for a short time in dilute hydrochloric acid, the calcium
carbonate will be entirely dissolved out, leaving a porous mass of
membranous animal matter, of the same form as the original shell
or fragment.

Pearls proper are globular masses of substance that are formed
in the muscles and other soft structures of the animal. They occur
in various species of oysters and mussels, both freshwater and
marine, and are often so highly esteemed that the ‘ pearl fisheries ’
have taken a prominent place among the industries of certain
countries.

The finest pearls are obtained from marine species, but river
mussels have also yielded very valuable specimens, in illustration
of which may be cited the once famous Scotch pearl fisheries,
carried on principally in the river Tay.

The structure of a pearl closely resembles that of a nacreous
shell, the same three layers being discernible, but with their order
reversed—that is, the outer layer of the pearl corresponding with
the inner one of the shell.

FRESHWATER MOLLUSCS 157

The nucleus of the pearl generally contains a speck of organic
matter. This is surrounded by a layer of calcareous substance, upon
which are deposited alternate layers—exceedingly thin laminiwe—of
mineral and animal matter.

These layers are generally much thinner than in the nacreous
layer of the shell, and are also more transparent ; and this, and the
minute corrugations into which the lamine are moulded, are pro-
bably the cause of the beautiful iridescence that enhances the value
of the gem.

The colours of pearls vary considerably with the species in
which they are found, green, pink, violet, and other shades being
more or less common; and it appears, too, that the formation of
pearls in any one species varies considerably according to local
circumstances and other causes which seem to be but little under-
stood.

In connection with this latter statement it is curious to note
that out of a number of bivalves, all of one species, and taken from
the same bed, a few may have developed pearls, while all the others,
reared under exactly the same circumstances, show no signs of
them. An attempt to explain this has been given us in the state-
ment that certain individuals have a predisposition to develop
pearls.

Such a statement may at first seem to be meaningless, but we
must remember that pearl development is to be regarded as a
disease, being the result of an irritation applied to one or other of
the soft animal structures ; and most of us are willing to admit that
such predispositions to develop certain diseases are to be met with
among our own kind.

It has been asserted that pearls are always the result of a
deposit of animal and mineral substance round a grain of sand
which has become lodged in a soft tissue; also that the Chinese
increased their takings of the gems by first securing the bivalves,
charging them with grains of sand, and then replacing them in the
water for the irritant to do its work.

Others are of opinion that the irritation is the result of foreign
organic matter, such as small animals that are taken into the system
with the water current of the inhalent siphon, or of internal para-
sites ; but whether this be so or not, it is certain that only a very
small proportion of those pearl-producing bivalves which are found
with grains of sand within them are capable of producing pearls.

158 LIFE IN PONDS AND STREAMS

We must now notice the distinguishing features of the British
Unionide or pearl producers.

These are all large molluscs, with oblong or elongated shells,
the valves of which are equal but not equilateral. The prismatic
layer is not very thick, but the ‘epidermis’ or outer horny
layer, which is usually of an olive or brown colour, is strongly
developed.

The ligament is external and very conspicuous, and aged shells
are often thickened by heavy deposits of nacreous matter, and are
also frequently very much eroded or worn away.

In some species teeth are entirely wanting, but where these
exist, the cardinal teeth are usually large, and the laterals either
striated or laminar.

The mantle lobes are free at their edges, except at the posterior
end, where they are united to form the two siphons, as we observed
in the case of Anodonta; and the foot is large and tongue-shaped.

The British species contain representatives of two genera—
Unio and Anodonta—and number in all only five, three belonging
to the former, and two to the latter genus.

Fic. 134.—Vatyr or Unio Margaritifer, sHow1Inac THE TEETH AND
THE MuscunaR IMPRESSIONS

The two genera may be easily distinguished as follows: In
Unio the shell is very strong and solid, particularly the aged speci-

FRESHWATER MOLLUSCS 159

mens. The cardinal teeth are usually large ; and the lateral teeth,
which exist on the anterior and posterior sides of both valves, are
laminar in structure, and those on the posterior side are the longer.

In Anodonta the shell is somewhat similar in general form,
but is much thinner, and there are no teeth. The valves of young
specimens are compressed, but as age advances they become
ventricose or swollen in the middle.

The three species of Unio are often called the river mussels,
being obtained chiefly by dredging in running water; but two of
them-—U. twmidus and U. pictorwm—may be found in large ponds
and lakes as well as in streams. These two are pretty widely
distributed in England, and have also been taken in Montgomery-
shire in Wales, but are not known in Scotland or Ireland.

The other—U. Margaritifer—is met with in the gravelly beds
of rapid streams and rivers of the mountainous districts of the north
of England, Wales, Scotland, and Ireland ; but is not found in the
south.

Fic. 135.—Sueiui or Unio pictorum, SHOWING THE TEETH

The reader will be able to identify U. tumidus and U. pictorum
by the aid of the illustrations on Plate II, where it will be observed
that the former shell is of an oblong form, and the latter a more

160 LIFE IN PONDS. AND STREAMS

elongated oblong. The umbones of U. twmidus (Plate TI, fig, 2) are
rather prominent and wrinkled, while those of U. pictorwm (Plate
IT, fig. 8) are not so prominent nor so wrinkled, and the ligament
is longer than in U. tumidus. There are also differences in the
form of the teeth, the anterior set of U. twmidus being prominent
and conical, while those of the other species are compressed.

U. Margaritifer is a very dark brown shell, ovate in form, thick
and heavy, and attains almost twice the length of the two preceding
species, both of which rarely exceed three inches.

The two species of Anodonta—Cygnea (fig. 186) and Anatina
(Plate IT, fig. 4)—are very similar in external appearance, but the

ox

Fie. 136.—Anodonta cygnea

latter is much smaller, seldom exceeding three and a half inches in
length, while Cygnea sometimes reaches eight or nine inches. The
shell of Anatina, too, is more glossy, and more compressed above
and behind; and the ligament is decidedly shorter than that of
Cygnea. Both species are found in ponds, lakes, canals, and slow
rivers, and are widely distributed in England. They have also
been taken in a few counties of Wales, Scotland, and Ireland; but
Anatina is more local than Cygnea.

Family DREISSENID/As

This family is named after Dreyssen, a Belgian naturalist,
and has only one-British representative—Dreissena polymorpha

FRESHWATER MOLLUSCS 161

(Plate IT, fig. 5)—really a native of the East, inhabiting the rivers
which flow into the Caspian and the Sea of Aral.

It was introduced into England in the early part of the present
century, probably attached by its byssus to imported timber. It
was first discovered in the Surrey
Docks, and has since spread into
the canals, rivers, and ponds of
many of the English counties, and
into a few districts in the south of
Scotland.

The shell is somewhat mussel-
shaped, but triangular, with the
umbones at one end. Both valves
are bluntly keeled, and the right one has an opening through which
the byssus and the foot protrude. The ligament is internal, and the
teeth are either small or absent.

The shell is a pretty one, the colour being yellowish or greenish
brown, and marked with zigzag transverse bands of dark brown or
brownish purple.

The animal has a closed mantle.

Fic. 137.—Dreissena
polymorpha

FRESHWATER UNIVALVES

We have now to consider the other great division of the Mollusca,
of which the common snail was chosen as a type.

This division, it will be remembered, is termed the Gasteropoda ;
and, since the greater number of its members are protected by a
single calcareous shell, the whole are often spoken of collectively as
the wnivalve molluscs.

In some the shell is entirely wanting ; in others it is represented
by a few granules of calcareous matter or a small plate of the same
material, which may or may not be concealed beneath the surface
of the mantle.

In all, the body has a distinct head, with one or two pairs of
tentacles, and eyes situated on the summits or at the bases of these
appendages.

Many of the Gasteropods are terrestrial in their habits, and these
all breathe by means of lungs, like the common snail; but a very
large number inhabit salt, brackish, and fresh waters, and these
breathe partly by lungs and partly by gills.

M

162 LIFE IN PONDS AND STREAMS

We observed that the common garden snail closed its shell, at
intervals of rest and during periods of hibernation, by means of a
slimy mucus that is secreted by the mantle, thus fixing its shell on
the surface to which its foot was attached, and securing itself to a
certain extent from its foes.

But many of the univalves have a lid of horny or calcareous
matter attached to the back of the foot in such a manner as to par-
tially or completely close the mouth of the shell when the animal
retires within.

This lid is called the operculum, and must be familiar to every
one who has seen the common periwinkle or one of its edible
relatives.

If we examine an operculum we find that it is marked with
striations more or less distinct. These are generally closed curves,
one within another, and all surrounding what is called the nucleus.

The nucleus represents the original operculum of the young
shell, and the striations surrounding it are the lines of growth,
marking the areas added successively as the shell increased in
size.

Thus it will be understood that the operculum increases in size
by additions at its circumference ; and if the growth is equal on all
sides, the nucleus remains central; but if the additions are made
more rapidly on one side, the nucleus becomes excentric.

The British aquatic univalves represent two distinct orders—
the Pectinibranchiata or comb-gilled, and the Pulmonobranchiata
or lung-breathers.

In the former the shell is spiral and its mouth operculated. In
the latter the shell is also spiral, at least as far as the British
aquatic species are concerned, but the mouth is usually non-opercu-
lated.

The Pectinibranchs include three families—the Neritida, the
Paludinide, and the Valvatide.

The Neritide have thick semiglobular shells, with a small com-
pressed spire at the side. The shell is composed of about three
whorls, but the first and second of these are exceedingly small com-
pared with the body whorl. The internal cavity does not exhibit
that complexity of structure common to most spiral shells, the
internal parts of the shell having been absorbed. The aperture,
however, is partially closed by a flat expansion of the shell on the
columellar side, thus giving the mouth a semilunar form (fig. 138).
The operculum is calcareous. ‘The animal has long and slender

FRESHWATER MOLLUSCS 163

tentacles, and the eyes are mounted on pedicels at their bases.
The foot is triangular or oblong.

The second family—Paluwdinide—is characterised by a conical
or globular shell, usually of an olive-green colour. The mouth is
oval, and its margin (peristome) is complete. The operculum is
sometimes horny and sometimes calcareous. The gills are internal,
the tentacles long and slender, and the eyes are either sessile (not
stalked) or mounted on small pedicels at the base of the tentacles.

The third family— Valvatid@—has a conical shell, which is some-
times so depressed that it is almost discoidal. The mouth is cir-
cular, with a complete peristome, and the operculum is horny.
The tentacles, two in number, are long and slender, with eyes
situated at their bases. The animal breathes by means of long
plumelike gills, which are partially protruded on the right side when
it is crawling.

The following table will assist the reader in grouping his shells
into their respective families, previous to the determination of the
genera and species :

Order Pectinibranchiata

Shell spiral. Mouth closed by an operculum. Animal breathes
by gills.
(a) Shell semiglobular; spire flat; mouth semilunar.
Family NERITID.
(6) Shell conical or depressed ; peristome almost complete.
1. Shell swollen ; mouth oval ; gills internal.
Family PALUDINIDE.
2. Shell depressed (conoid or discoid) ; mouth round; peri-
stome complete; gill long, plumelike, protrusile.
Family VALVATID.

Family NERITID®

This family contains only one British species—Neritina fluvia-
tilis, which is found attached to
stones at the bottom of rivers
and canals in many parts of Ge ae CD)
England, and in a few localities
in Scotland and Ireland. Fic. 138.—Neritina fluviatilis
The shell is ovate in form,
of a yellowish, grey, or brownish colour, and generally chequered
M2

164 LIFE IN PONDS AND STREAMS

with little elongated patchés of various tints. The operculum is
semilunar, yellowish, with orange round the edge ; and on its under
side is a spiral projection. Our illustration of the shell is twice the
natural dimensions, the real size being denoted by the outline
drawing.

Family PALUDINIDA

This family contains the genera Paludina and Bithynia, in each
of which we have but two species.

The eggs of Paludina are hatched within the body of the parent ;
and during the early part of the summer, the young, in different
stages of development, may be dissected out, some of them being
quite a quarter of an inch in length. ;

The whorls of the shell are very convex ; the mouth is angulated
on the outer side; and the operculum is horny, with concentric
lines of growth.

SSeS

a

ii
\\\ KK Mi y

——~

ban

F ehadsbeh ‘il

f
UK

| . “awe

Fic. 139.—Paludina vivipara Fie. 140.—Paludina contecta

The commonest species—P. vivipara—is found in ponds, canals,
and slow rivers in many parts of England, but does not seem to
have been taken in the sister countries. It may be readily recog-
nised by reference to Plate IT, fig. 6, and the accompanying wood-
cut shows the form of the mouth and operculum, and the narrow
slit representing the umbilicus.

The other species—P. contecta—is slightly larger; and the
ground colour, which is darker, is relieved by brown bands as in
Vivipara. The whorls of the shell are more rounded, the suture
deeper, and the umbilicus more distinct. This species, though not
<o widely distributed as the last, is found in ponds and canals in
many parts of England.

The two shells of the genus Bithynia are very much smaller ;

FRESHWATER MOLLUSCS 165

the larger—that of B. tentaculata—being half an inch in length,
and the smaller (B. Leachii) only a quarter of an inch.

Both these species are oviparous, and both are easily reared in
an indoor aquarium. The eggs are laid in regular bands on the

Fic. 141.— Bithynia Fie. 142.—Bithynia Leachii,
tentaculata ENLARGED

stones and weeds in ditches and sluggish streams; and, in the
artificial aquarium, frequently on the glass. It has been said that
the molluse invariably cleans the surface on which it deposits its
eggs. This it undoubtedly does as a general rule, and the operation
may be watched most readily when the glass of an aquarium is
chosen as the material on which to lay; but I have often seen the
eggs of B. tentaculata deposited on such a dense confervoid growth
that they were hardly visible when viewed from the outside of the
aquarium. Theanimals are full grown in the spring of their second
year.

The operculum of Bithynia differs from that of Paludina in
that it is impregnated with carbonate of lime, and is therefore hard
and brittle, while that of the latter genus is horny and flexible.

The smaller species may be distinguished from B. tentaculata
by the following marks: the shell has only about four and a half
whorls, while that of B. tentaculata has six. The whorls are more
swollen, and separated by a deeper fissure. The mouth is almost
circular, while that of the other species is oval, and angular above.
In B. Leachii, too, there is an umbilicus, but this is absent in
Tentaculata.

Both the shells are widely distributed, the larger being found in
all the divisions of the United Kingdom. ‘They are mostly met with
in the southern counties, and B. Leachii, which is more restricted
than Tentaculata, has not been taken in Scotland or Ireland.

A third genus, called Hydrobia, is often included in this family.
It contains a shell (H. similis) which is to be found in the Woolwich
Marshes, in ditches which receive the brackish water of the Thames
at each flood tide. It is somewhat like PB. tentaculata, but the
operculum is horny, and a very narrow uibilicus exists.

166 LIFE IN PONDS AND STREAMS

Family VALVATIDA

This family contains only two British species, and these both
belong to the genus Valvata.

The larger of these (V. piscinalis) is shown in two positions in
fig. 143, and the smaller (V. cristata) in fig. 144. In both these
illustrations the reader will observe the depressed spire, especially

0 iM
Fic. 143.— Valvata piscinalis, Fic. 144.— Valwata
ENLARGED cristata, ENLARGED

of V. cristata, which is so reduced in height that the shell is almost
a disc. The circular mouth, with its complete peristome, will also
be noticed; as well as the large and gaping umbilicus of V. »iscv-
nalis.

Both species are widely distributed in Great Britain, Piscinalis
appearing to have the greater range ; but it is doubtful whether the
small size of Cristata does not cause it to be frequently overlooked
when its larger relative would have been seen and secured.

We will conclude our remarks on the Pectinibranchs by giving
the reader a tabular view of the whole group.

Order Pectinibranchiata

Shell spiral. Mouth closed by an operculum. Animal breathes
by gills.
(a) Family NERITIDA‘.—Shell semiglobular ; spire flat and
lateral ; mouth semilunar.
Genus Neritina. One British species. N. fluviatilis.
(b) Family PALUDINIDA‘.—Shell conical or discoid. Mouth
closed by an operculum. Animal breathes by internal
gills.
1. Genus Patupina.—Shell conical; swollen. Mouth
oval; peristome almost complete. Operculum horny.
Animal ovoviviparous.

FRESHWATER MOLLUSCS 167

A. Shell greenish. Umbilicus very narrow or absent.

Mouth angulated. P. vivipara.
B. Shell olive-green. Umbilicus distinct and deep.
Mouth nearly circular. P. contecta.

2. Genus Birnynra. Shell conical. Operculum shelly.
Animal oviparous.
A. Shell of six whorls. Mouth angulated. Um-

bilicus absent. B. tentaculata.
B. Shell of about four whorls. Mouth round. Um-
bilicus distinct. B. Leachii.

(c) Family VALVATID.—Shell depressed. Mouth round.
Peristome complete. Gill protrusile and plumelike.
Genus VALVATA.
A. Shell subglobular. Spire compressed.
V. piscinalis.
B. Shell discoid. Umbilicus large. V. cristata.

THE LUNG-BREATHING UNIVALVE MOoLLUscs

The lung-breathing gasteropods form the order Pulmonifera or
Pulmonobranchiata.

This order includes all the land snails, slugs, and the greater
number of the water snails.

The breathing organ of these molluscs is a simple pulmonary
sac, like that which we observed in the case of the garden snail,
surrounded by a closely set network of blood capillaries.

The shell is generally well developed, and in the form of a
spiral; but in some it is conical, and in others it is merely a cal-
careous plate, or is represented by a few granules of a limy deposit.
In some cases the mouth of the shell is closed by an operculum,
but not in any of our freshwater species.

The order contains about twenty-five species that inhabit our
ponds and streams, and these represent only one family—the
Limneide, of which the following are the chief distinguishing
characteristics :

The shell is thin, of a yellow or brownish colour, and is either
spiral or-conical. The animal has a short and broad muzzle,
two ‘tentacles, and sessile eyes. The teeth are very like those of
the common garden snail, and the upper mandible is also much
like that of the same species.

The greater number of the Limneide are easily kept and bred

168 LIFE IN PONDS AND STREAMS

in a small aquarium. They feed chiefly on vegetable matter, both
fresh and decaying; and some of them greedily attack decomposing
animal matter, and are therefore likely to prove very useful at times
as scavengers of the aquarium as well as of the stagnant pond.

They lay their spawn on the vegetation, stones, glass, or any
other surface at hand. It is an elongated oval mass of gelatinous
substance with the germs embedded in it; and being transparent
the development of the young may be watched with the greatest of
ease.

They hibernate in mud during the cold weather, but several of
the species may be taken with the net from weeds during mild days,
even in the middle of the winter.

The genera of this family, at least as far as they concern us at
present, are Planorbis, Physa, Limnea, and Ancylus; the first
three including what are commonly known as ‘ water snails,’ and
the last the ‘ freshwater limpets.’

The flatly coiled and discoid shell of Valvata cristata—the last
we examined of the Pectinibranchs—closely resembles that of the
first of these genera, for the most striking characteristic of Planorbis
is a many-whorled shell, the coils of which lie almost in the same
plane. The mouth of the shell, however, differs from that of V. cris-
tata, for it is either semicircular, semilunar, or crescent-shaped, and
has no operculum. ‘The peristome is also very thin, and is extended
on the upper side, so that the cavity of the mouth cannot be seen
from above. The animal has a short round or oval foot, and a pair
of long and slender tentacles with the eyes at their bases.

The next genus is called by a name (Physa) which signifies a
pouch. The shell is an elongated oval, very thin and glossy. The
spiral is sinistral or left-handed (page 139) ; the mouth is rounded in
front and has no operculum. The mantle is expanded and covers
part of the shell, and in some species is edged with a fringe of long
filaments. The tentacles are long and slender, and the eyes are
situated at their bases.

The third and typical genus of the family is Limnea, the name
being derived from a Greek word which means‘ a marsh.’ In
this division the shell is oval, with a dextral or right-handed spiral
more or less elongated. It is thin and semi-transparent, and the
mouth, which is oval or oblong, has no operculum. The animals
of this genus may be readily recognised by the short and wide head,
with its two triangular tentacles, and eyes at their bases. The foot
is oval.

FRESHWATER MOLLUSCS 169

¢

The last genus—Ancylus (agkulos=a small shield)—may be
known at once by the conical limpet-shaped shell, the base of which
is of an oblong-oval form. The cone is not symmetrical, but has
its apex nearer the posterior end. The apex is also bent towards
one side, and thus the shell may be regarded as a spiral, in which
case it may be either sinistral or dextral. The foot is large and
oval, the tentacles triangular or conical, and the eyes situated at the
bases of the latter.

Again I give the chief distinguishing characteristics of the
groups in such a form that they may be seen at a glance by the
reader when classifying his specimens.

Family LIMNAIDZE

Shell thin, spiral or conical. No operculum. Eyes sessile.
Animal breathes by a lung.
1. Shell spiral, discoid. Mouth semicircular, semilunar, or
crescent-shaped. Genus PLANORBIS.
2. Shell oval.
(a) Spiral sinistral. Mouth rounded in front. Mantle
expanded. Tentacles long and slender. Genus PuHysa.
(6) Spiral dextral. Mouth oval. Tentacles triangular.
Genus LIMnz%A.
3. Shell conical (limpet-shaped). Tentacles conical.
Genus ANCYLUS.

Genus PLANorBIs.—This genus is rather a large one, containing
about a dozen British species. There is not space for a detailed

Fie. 145.—Planorbis lineatus, ENLARGED

description of each of these; and so, after a few general remarks,
I shall put the leading characters, by which we identify the species,
in a tabular form.

First, as to their distribution, most of them have a rather wide
range, and some are very common in most parts of Britain.

170 LIFE IN PONDS AND STREAMS

P. albus, spirorbis, vortex, complanatus, and contortus are all
widely distributed and more or less common. Nitidus, Nawtileus,
Carinatus, and Corneus are more local. Lineatus and Parvus are

Fic. 146.—Planorbis nitidus, ENLARGED

very local ; and Dilatatus, which has been introduced by the agency
of our shipping trade, is to be found only in canals in the neighbour-

hood of Manchester.

Fic. 147.—Planorbis Fic. 148.—Plancrbis albus,
nautileus, ENLARGED - ENLARGED. BRIsTtLES REMOVED

Several species thrive well in the indoor aquarium, requiring no
attention whatever if once supplied with suitable vegetation. In

Fie. 150.—Planorbis

Fic. 149.—Planorbis parvus : ‘
sptrorbis

illustration of this statement I may mention that I have now a
considerable number of a few species (Albus, Spirorbis, Vortex

Ven 4 (ly © bis ; :
Fic. Fe Ge Fie. 152.—Planorbis carinatus

Complanatus, and Corneus) in a twenty-gallon aquarium, all the
issue of a dozen or two introduced about three years ago, since

FRESHWATER MOLLUSCS 171

which time the water has not been changed once. It should be
known, however, that young univalves are not so successfully reared
in the presence of fishes or carnivorous beetles. The latter, in fact,

Fic. 153.—Planorbis - Fie. 154.—Planorbis corneus
complanatus (SEE ALSO PuaTe II, ric. 7)

will attack molluses of all sizes, even biting through the thinner
shells to obtain their prey ; and the former, sticklebacks in particular,
swallow the young as soon as they are liberated from the spawn.
If it is desired to rear molluscs
successfully from the ova, they
should always be kept quite
isolated ; or, at any rate, per-
fectly free from all creatures of Fic. 155.—Planorbis contortus,
carnivorous tendencies. sar rig

Much has been said about the value of water snails as scavengers,
and for keeping the glass of an aquarium free from confervoid
growths. As scavengers for bringing about the effectual removal of

Fig. 156.—Planorbis dilatatus

decomposing organic matter, this statement is certainly true of
Planorbis and the other Limneide; but, as to the removal of
confervoid growths on the glass, I have observed that they often
crawl over such growths without making the least impression on
them.

The following table deals with the principal distinguishing
features of the species of the Planorbis genus:

172 LIFE IN PONDS AND STREAMS

Genus PLANORBIS

Shell spiral, flat. No operculum. Tentacles long and slender.
Foot small, round or oval.
I. Shell convex above, flat below (quoit-shaped).
(a) Whorls four or five. Shell yellowish, polished.

1. White transverse plates, visible from exterior, in outer
whorl. Umbilicus narrow, deep. Diameter one-fifth of
an inch. P. lineatus.

2. Outer whorl wide, overlapping the next. Umbilicus
small, shallow. Diameter one-fifth of an inch.

P. netidus.
(b) Whorlsthree. Dull brownish. Concavity above. Strongly
marked transverse ridges on exterior. Umbilicus large.
Diameter one-ninth of an inch.
3. P. nautileus.
II. Shell not quoit-shaped.
(a) Convex above; concave below. U:mbilicus large. Mouth

rounded.

4. Whorls five. Shell whitish, bristled. Diameter one-
quarter of an inch. P. albus.

5. Whorls five or six. Shell brownish, polished. Concavity
above. Diameter one-sixth of an inch. P. parvus.

(6) Shell flat.
A. Umbilicus deep.

6. Very convex below. Keeled. Whorls two. Mouth
large and square. Diameter one-tenth of an inch. _

P. dilatus.
B. Umbilicus shallow.

7. Slightly concave above or below. Slightly keeled.
Whorls six. Mouth round. Diameter one-quarter of an
inch. P. sptrorbis.

8. Shell very flat. Keeled. Whorls seven or eight. Mouth

rhomboid. Diameter three-eighths of an inch.
P. vortex.

9. Slightly concave above ; slightly convex below. Sharply
keeled a little below the middle. Whorls five or six.
Mouth oval. Diameter half an inch. P. carinatus.

10. Slightly concave above and below. Sharply keeled
below. Whorls five or six; outer one larger than in

FRESHWATER MOLLUSCS 173

Carinatus. Mouth rhomboidal. Diameter three-quarters

of an inch. P. complanatus.

(c) 11. Shell much swollen; reddish brown. Not keeled.
Whorls five. Mouth semilunar; wide. Diameter three-
quarters to one inch. P. corneus.

(d) 12. Shell flat above; very convex below. Whorls eight,
much compressed laterally ; outer one very large. Mouth
crescentic ; very narrow. Diameter one-fifth of an inch.

P. contortus.

The above table should enable the beginner to identify most of
his specimens of the Planorbis genus without trouble, but he should
remember that he must always be prepared to meet with variations
in form, size, and colour, which will at first cause him a little
trouble.

In some cases (and these remarks apply not only to Planorbis,
but also to a considerable number of species, both univalve and
bivalve) the variations are themselves very variable in character,
almost every possible gradation between the extreme and the
normal being obtainable. But we sometimes meet with a striking
abnormity of size, form, or colour which has become permanent in
certain localities, thus producing what we call a variety. These
permanent varieties have fixed names, which are appended to the
ordinary names of the species to which they belong.

Thus the common species Planorbis corneus, which usually has
a dark reddish-brown shell, is sometimes found perfectly white; and
the variety, which, by the way, is not particularly rare, is known as
Planorbis corneus, var. albina.

The study of variation in animal life is most interesting, and the
collector of natural history objects should always be on the look-out
for all kinds of abnormities, and compare those obtained very care-
fully with the normal specimens.

It would be impossible to deal with the varieties of the different
species in the space at disposal. My aim is to supply the reader
with a general outline of the structure and the broad principles
of classification; but should he, after a few seasons’ collecting,
desire to make a special study of variation as exhibited in the
shells of molluses, he should refer to one of the manuals devoted
especially to this branch of natural history.

Genus Puysa.—The shells of this genus may be readily distin-
guished from the other spiral shells by the sinistral or left-handed

174 LIFE IN PONDS AND STREAMS

turn. They differ from the Paludimide@ in having no operculum ;
and may be known at once from the genus Limnea by the two
long and slender tentacles, as well as by the extended mantle.

There are only two British species of this genus, if we exclude
one (P. acuta) which has been introduced into this country some-
what recently, and which is to be found only in the Kew Botanical
Gardens.

The larger of these (P. hypnorwm) sometimes reaches three-
quarters of an inch in length. The shell is an elongated oval,

thin and _ polished, of

a yellowish or reddish

colour. The mouth is of

i an elongated oval form,
pointed above, and a little

more than half the length

Fie. 157.—Physa Fie. 158.—Physa of the shell. This species
hypnorum fontinalis is widely distributed, but

is somewhat local.

The other species (P. fontinalis) is smaller, being generally less
than half an inch in length. The shell is oval, thin, and transparent ;
and may be distinguished from P. hypnorwm by the deeper suture,
and also by the larger porportionate size of the last whorl, which
forms more than three-fourths of the length of the shell.

This species is far more common and more widely distributed
than the last. Both inhabit ditches and sluggish streams.

Genus Limn2A.—Most of the shells of this genus are remark-
able for the number of their varieties, and the young collector must
therefore be prepared to meet with many features not mentioned in
the table which follows.

Fic. 159.—Limnea glutinosa Via. 160.—Limnea
peregra

L. peregra, stagnalis, palustris, and truncatula are common in
ponds, ditches, and sluggish streams in most parts. L. glutinosa,
auricularia, and glabra are local, particularly the first and last

FRESHWATER MOLLUSCS 175

mentioned. The other (L. involuta) has been taken only ina small
lake in the Killarney district.

As already mentioned, these molluscs thrive and breed well in
aquaria, and are, moreover, very useful for the removal of decom-
posing matter, which forms their principal food.

Fis, 161. Fie. 162. Fic. 163. Fic. 164.

Limnea Limnea palustris Limnea Limnea
auricularia truncatula glabra

L. stagnalis (Plate II, fig. 8), being a very large species, is orna-
mental as well as useful; and the muscular movements of the foot
are to be observed very easily as the creature creeps over the glass,
or, in an inverted position, on the surface film of the water.

L. peregra feeds on decomposing animal as well as vegetable
matter, and is therefore useful in reducing this dangerous source of
contamination.

The following is a tabular arrangement of the members of this
genus:

Genus LIMN2A

Shell oval or conical; spiral; no operculum. Animal with two

short triangular tentacles.

A. Shell oval, pale yellowish, thin, polished. Whorls three to
five, the last forming the greater part of the shell. Spire
small.

1. Shell globose. Whorls three or four. Mouth oval, about
three-fourths the length of the shell. Length half an inch.
L. glutinosa.

2. Whorls three or four. Spire sunken. Mouth large and
pear-shaped. Length nearly half an inch. L. involuta.
3. Whorls five. Spire extended and sharp. Mouth oval, about
two-thirds the length of the shell. Length half to seven-
eighths of an inch. L. peregra.

4. Shell globose, Whorls four; last much expanded. Spire

176 LIFE IN PONDS AND STREAMS

very short; acute. Mouth much expanded, about five-
sixths the length of the shell. Length three-quarters to one

inch. L. auricularia.
B. Shell conical; tapering. Whorls five to eight. Spire long;
acute.

5. Whorls six to eight; boldly striated. Mouth oval; rather
over half the length of the shell. Length one and a half to
two inches. L. stagnalis.

6. Shell thick, brown. Whorls six, separated by a fine white
line. Mouth ovate; nearly half the length of the shell.
Length one-third to three-quarters of aninch. L. palustris.

7. Whorls five or six. Suture very deep. Mouth ovate; less
than half the length of the shell. Umbilicus distinct.
Length half an inch. L. truncatula.

8. Shell an elongated cone. Whorls seven or eight. Mouth
oval; narrow; less than one-third the length of the shell.
Length three-quarters to one inch. L. glabra.

Genus AncyLus.—This is the last genus of the family Limnea.
It has only two British species, which are sometimes termed the
freshwater limpets. Both are small, and one (A. lacustris) inhabits
still or very sluggish waters, while the other (A. fluviatilis) is found
only in streams.

A. lacustris is generally stationed on weeds, and its small conical
shell fits so closely on the surface of the vegetation that it is liable

Fic. 165.—Ancylus lacustris, NATURAL SIZE AND ENLARGED

to be overlooked if not closely observed. The shell, too, is so very

thin that it is often difficult to remove it without injury; for the

animal holds on firmly by means of its broad oval foot. Those in

search of this shell should carefully examine

@ la) the surface of the leaves of flags and other

aquatic or semi-aquatie plants, including the

Fic. 166.—Ancylus ead and decaying leaves which may be quite
fluviatilis detached and lying on the bed of the water.

A, fluviatilis is larger than Lacustris, and

the base of the shell is a broader oval. It may be found on weeds
and on the surface of stones in rivers and streams.

FRESHWATER MOLLUSCS 177

Lacustris is local, but common in some parts. Fluviatilis is
common in most parts except in the extreme north.

SEMI-AQUATIC MoLuuscs

Those who devote their leisure hours to the-observation of life
in ponds and streams are sure to meet with many creatures of semi-
aquatic habits—creatures which spend a portion of their existence
only in the water, and the remainder either on the surface or in the
immediate neighbourhood ; and others which are never aquatic in
the strictest sense of the term, but which show their partiality for
the water by making their homes in the damp soil of marshes and
the banks of ponds, ditches, and streams, or on the semi-aquatic
plants that derive their food from ground saturated with water.

Such creatures may well be considered within the legitimate
province of a water-searcher’s labours, and among them we have to
place a certain group of ‘ snails’ that are more generally classed with
terrestrial species, but which are always found near water, either in
marshes, or on plants that grow on the banks of ditches, streams,
and ponds.

The group referred to (genus Swccinea) belongs to the family
Helicide, which contains the common snail (Helix aspersa) that
was, as a matter of convenience, chosen for our examination as a
type of the Gasteropods.

It will hardly be necessary to recall the various points in the
anatomy of this type, but it may be observed here that the chief
feature by which these semi-aquatic snails are to be distinguished
from their truly aquatic relatives is the presence of four tentacles,
cylindrical in form, the dorsal and longer
pair bearing the eyes at their summit.

In the genus Suwccinea the shell is spiral,
of an oval or oblong form, and very thin.
The spire is generally very short, and the
mouth, which is very large, has no oper-
culum. The tentacles are much shorter in», Uy ee: ee
proportion than in Heliz. putris

Perhaps the commonest species is S.
putris, which measures from a half to nearly three-quarters of an
inch in length, The shell is ovate in form, thin and transparent,
polished, and of a pale amber colour. There are three or four
whorls, and the mouth is quite two-thirds the total length of the

N

178 LIFE IN PONDS AND STREAMS

shell. This species may be found on flags and other semi-aquatic
plants in most parts.

Another molluse—S. virescens—is sometimes regarded as a
variety of S. putris, and not a distinct species. It is smaller than
S. putris, however, seldom reaching half an inch in length, and is
of a delicate greenish colour. It occurs in some districts round
London, and in a few other isolated localities.

A third species—S. elegans—is
very common in many parts, but
far more local than S. putris. Its
shell is not so transparent as the
preceding. It is also narrower, and
the spire is extended and more
acute. It reaches about half an
inch in length. Another one, S.
Pfeifferi, is of about the same size, but the shell, which is trans-
parent, is of a deep amber or reddish tint; and the spire, which is
shorter, is swollen. ‘This is also a local species, but common in the
districts where it exists.

To the above may be added a much rarer species, S. oblonga,
which seems to have a partiality for salt, as it inhabits only the
banks of ditches close to the sea. It is a quarter of an inch long,
of a pale yellowish colour, and the mouth is half the length of the
shell. Although rare, it is very widely distributed.

Fic. 168.—Succinea elegans

179

CHAPTER IX
FRESHWATER CRUSTACEANS AND SPIDERS

WE have now to deal with that large sub-kingdom of animal life
called the Arthropoda, which includes a vast number of creatures
that are distinguished by a hardened protective skin made up of
a number of segments, each bearing a pair of appendages.

Although there are considerable variations in the form and size
of the different segments, even in the same animal, yet all are con-
structed on the same plan. Each consists of an upper or dorsal
plate, usually convex above, and a lower or ventral plate, also
generally convex on the outer side; and the appendages arising
from the segment are attached at or near the points where these
two plates meet.

The appendages of Arthropods also consist of a number of
jointed parts, and are all surrounded by a hardened skin similar to
that which covers the body. Three or more pairs of these appen-
dages are used for purposes of locomotion either on land or in
water, and the others are modified for the performance of certain
special functions, such as prehension, the crushing or sucking of
food, or as organs of sensation.

We shall observe that the Arthropods are as a rule much more
highly developed than any of the creatures already described,
though in many respects they resemble the worms. They have
generally a very complicated digestive system; and, unlike the
simply formed soft-bodied animals, have special well-developed
organs of respiration by means of which air can be obtained either
from water or direct from the atmosphere. The nervous system
consists of a chain of little masses of nerve substance (ganglia)
arranged longitudinally along the lower part of the body, all con-
nected by nerve cords, and giving off radiating nerves to the various
parts of the body.

Hitherto we have been considering forms of animal life which

N2

180 } LIFE IN PONDS AND STREAMS

are not generally well known except to students of natural history.
They are either too small to attract the attention of ordinary
observers, or they are too far down the scale of life to be worthy of
notice; but the Arthropoda contain a large number of creatures
that are not only well known to every one, but even admired more
or less by all, either on account of the beautiful colours they
display, or their interesting ways, the high degree of intelligence
they exhibit, or because they benefit mankind by supplying them
with food or some other useful commodity.

The sub-kingdom is divided into four classes: Crustacea,
Arachnoidea, Myriapoda, and Insecta.

The first of these includes Crabs, Lobsters, Crayfishes, Shrimps,
Prawns, and other smaller and less familiar animals. The Arach-
noidea includes Spiders, Mites, and Scorpions. The Myriapoda
embraces Centipedes and Millepedes; and the Insecta or Insects
need not here be defined.

The third of these classes will not engage our attention at all.
The present chapter is to be devoted to the aquatic Crustaceans and
Spiders; and the Insects are of sufficient interest to claim a some-
what lengthy chapter to themselves.

CRUSTACEANS

The largest of our freshwater Crustaceans is the River Crayfish
(Astacus fluviatilis), which is very common in many of our rivers,
especially those in chalky and limestone districts, but either scarce
or unknown in the streams which flow over granite and other hard
rocks containing little lime.

Crayfishes can generally be obtained without much difficulty
from dealers in aquarium pets; but if the reader is in a position to
search out the creatures in their haunts he should capture his own
specimens rather than apply to a dealer. And this remark applies
equally well to all the various kinds of aquatic animals that are
kept in captivity. Aquarium keepers often rely solely on this
method of stocking their vessels; but how much better is it to
gather one’s specimens oneself, not only because we naturally take
more pleasure in studying the creatures taken with our own hands
than those bought at a price, or because the mere employment calls
us out and gives us exercise in the pure country air, but mainly
because we are thereby furnished with an opportunity of watching
the creatures in their native element, and of studying their habits
and habitats.

FRESHWATER CRUSTACEANS AND SPIDERS 181

No particular apparatus is needed by the crayfish hunter. The
animals are to be caught without bait, and may be taken home
alive without a drain of water.

During the winter months crayfishes spend much of their time
in holes in the banks of rivers, and they are then so inactive that
they are easily dug out with a spade ; but this is the least interesting
of all the modes of capture—at least to the naturalist.

In France, where crayfishes are in great request as an article of
food, several very different modes of capture are practised. Some-
times baskets containing meat or dead frogs are let down into the
water, and then lifted out again quickly either when crayfish have
actually been seen to enter or when it is supposed that they have
done so. During the heat of the day they remain in their burrows
in the banks, or seek shelter from the sun’s rays under stones in
shallow water ; but in the evening twilight, and also after dark, they
roam about in search of food, and can then be taken in a dredge.
When this method is employed a strong light is sometimes thrown
on the water, not with the object of rendering the crayfishes visible,
but because the light attracts them just as it does certain insects.

The above methods are perhaps more suitable for the profes-
sional fisherman than for the aquarium naturalist. To the latter
there is nothing better than searching for the crayfishes in their
hiding places in broad daylight. They lie at the openings of their
nooks, generally with nothing protruding save their long antenne
and their claws. Here they are always on the alert both for their
food ‘and for their enemies. On the approach of the latter the
crayfish suddenly darts backward into its hole, never turning, but
always keeping its face to the foe.

The best way is to proceed slowly up the stream, wading in
water close to the bank, and watching for the slender antenne. As
a rule their holes are too small to allow the hand to pass, but the
crayfish can usually be pulled out easily by means of its antenne.

Of course the captor must not expect to engage in much of this
kind of sport without an occasional nip of the crayfish’s claws ; but
although the power of these limbs is considerable, and the first nip
or two is rather startling, one soon takes it all as a matter of course.

I have always found crayfishes thrive best in a large shallow
tank or trough, with large stones loosely piled in such a manner as
to provide numerous hiding places. The water should either be
always running, or set flowing at frequent intervals; and the
waste pipe should be at the level of the topmost stones.

182 LIFE IN PONDS AND STREAMS

As to feeding, crayfishes will eat anything, either vegetable or
animal, that satisfies our own appetites. They will devour many
kinds of pondweeds, and aquatic snails and other animals, the
shells of the former being devoured as well as the soft structures
within them. They also partake readily of carrot and turnip and
the stalks of cabbage—in short, anything ; but care should be taken
that no large excess of decomposable matter be allowed to remain
in the water, or it will soon become putrid and poisonous.

Now let us watch our captive crayfishes in order to acquaint
ourselves with their habits.

to cg cep a.

a3 GAZ aia)

Fic. 169.—Tue Crayrisu (Astacus fluviatilis)

r, rostrum or beak ; cep, cephale or head ; tho, thorax ; cg. cervical groove, between head
and thorax; ab, abdomen; br, portion of shell covering the gills; an, antenne ;
a 9-14, thoracic appendages

During the greater part of the day they remain hidden among
the piled stones provided for them, with their heads and foremost
appendages just visible. If we make a sudden approach towards
them, or threaten them by thrusting a stick before their holes, they
suddenly dart backward under cover; and if we then intrude within
their homes they will not hesitate to grasp the intruding object
with their large claws by way of defence.’

In the evening they come out to feed; and if we now approach
so cautiously as not to disturb them we may watch their move-
ments with ease. Their long antenne are now held forward, and
kept in motion as if to try the way. In fact these organs are
undoubtedly very sensitive, and serve the purpose of feelers like the
antenne of insects and the whiskers of the rat and other mammals.

FRESHWATER CRUSTACEANS AND SPIDERS 183

If now we threaten or alarm them, we shall be able to see by
what means the crayfishes are enabled to dart backward. As they
climb about over the stones we observe that the powerful jointed
tail is extended, and that they progress principally by means of
their five pairs of legs. When, however, we alarm the creatures
they suddenly double their powerful tails forward under their bodies,

Wisaws Seo

t])

Le ee

na
ef
we

Fria. 170.—TnHe CRAYFISH, UPPER SIDE

at the same time spreading out their flat and fringed terminal
appendages to their full extent, and thus retreat with a rapid series
of jerks till they reach the entrance of their home, into which they
then shuffle themselves backward, never for a moment turning
their back on the enemy.

The crayfish will also demonstrate the power of its muscular
abdomen in an amusing manner if we lift it out of the water,

184 LIFE IN PONDS AND STREAMS

grasping it between the finger and thumb at the thickest part of the
body. Not knowing that its powerful organ of retreat loses its effici-
ency when struck against the air, it flaps it vigorously, striking the
under side of its abdomen with considerable force at each movement.

With the creature still in our hand we will proceed to note its
external form and structure. Its skin is tough, and is hardened by

ms
sagfild §

en
Sm,

Fic. 171.—THe CrayFisnH, UNDER SIDE

a deposit of carbonate of lime except where flexibility is required,
as between the moveable segments of the hinder portion of the body ;
and this same skin is reflected inwards at the beginning and end of
the food passage, forming an almost complete lining for the whole
digestive tube.

FRESHWATER CRUSTACEANS AND SPIDERS 185

The body is seen to consist of two main portions—a large one in
front, consisting apparently of only one segment, and a hinder por-
tion composed of six segments moveable one on the other.

The large anterior part is the head and thorax combined, and a
depression on the upper surface of the great shield (the carapace)
which covers it marks the division between these two parts. The
whole, however, is not looked upon as a single segment, but is
regarded as consisting of fourteen segments all fused together ; for
not only has it fourteen pairs of appendages, but on the under side
we may observe traces of a division as just suggested.

In order to get an idea of the general character of each segment
or somite, we will examine one of the moveable divisions of the
abdomen. It has an arched portion above,
and a narrower and slightly convex bar
below ; and the former is prolonged down-
wards beyond its junction with the latter.
Then close to the point where the two
meet, on either side, an appendage is
situated.

The appendage in this instance is
called a swimmeret, and is made up of a
single basal joint, at the end of which are Fic. 172.—-TuHe rovurtH
jointed an inner and an outer part, both SEGMENT OF eo AB-
of which consist of several joints and are rae we SRR ye
fringed with hair. ON ONE SIDE

Each of the abdominal segments has
its pair of appendages, but in some cases they are very imperfectly
developed ; and those of the last one are modified to form the
broad and flattened tail, the use of which we have already observed.

If we bend the abdomen under the body we notice that the front
portion of the upper arch of each segment is very smooth ; and on
extending the body again, we see that this smooth portion slides
without friction beneath the hinder part of the segment immediately
in front of it.

It will be interesting now to look at the various appendages of
the large anterior portion of the body, which, we have learnt, forms
the head and thorax, and which is consequently termed the cephalo-
thorax.

The first of these are the eyestalks—two short cylindrical rods,
each of two joints, which carry the eyes at their tips.

The eye itself is a very wonderful structure, for it consists of a

186 LIFE IN PONDS AND STREAMS

number of little transparent pyramids, four- or six-sided, all
radiating from a point at the head of the stalk, and their bases
forming the outer convex surface of the eye.

Each pyramid is divided from its neighbours by a layer of cells
containing a very dark colouring matter; and the outer membrane
of the eye, which is a modified continuation of the skin of the whole
body, consists of a number of little facets or lenses, one forming the
base of each pyramid.

Thus the eye of the crayfish is compound. Every one of the
little facets has the power of converging the rays of light that pass
through it, and of forming an image within its pyramid; and con-
fusion of the different images formed by the various facets is pre-
vented by the opaque pigment that lies between the pyramids.
Further, at the apex of each pyramid there is a nerve fibre to receive
the light vibrations and transmit them to the large ganglia of the
head.

Of course we are not able to determine the nature of the cray-
fish’s vision, but only those rays which strike the convex surface
perpendicularly can penetrate the eye and reach the optic fibres, and
therefore each little compartment of the compound organ forms
its own image of the object that lies exactly opposite its central
axis.

Between and above the eyes there is a sharp projection of the
hardened skin, forming what is known as the beak or rostrwm, and
beneath this there is a pair of antennules or short antenne. These
are followed by a pair of long antenne, and both these and the
smaller ones are composed of a number of little segments.

And now, if we examine the under side of the head, we see
several pairs of appendages placed more or less closely round the
mouth. Taking them in their proper order, from before backwards,
the first of these is a pair of mandibles or jaws, strong and hard, one
on each side of the mouth. They move horizontally, and are
toothed like a saw on their inner edges. Then follow two pairs of
maxille, the second of which has a large and thin plate that les
hidden beneath the overhanging shield at the side of the head, and
concerning which we shall have more to say presently.

The twelve appendages above named are all regarded as belong-
ing to the head of the crayfish, and the head is looked upon as con-
sisting of six segments fused into one. Then follow the segments of
the thorax, eight in number, with a corresponding number of pairs
of appendages. ‘The first three of the latter are termed maxillipedes

FRESHWATER CRUSTACEANS AND SPIDERS 1&7

or foot-jaws, because they are used in conveying the food from the
large claws or pincers to the mouth.

The other five pairs of thoracic appendages are the long walking
legs, the first of which bears the powerful claws just mentioned, and
the second and third also exhibit rudiments of a pair of grasping
organs.

The remaining appendages are the swimmerets of the abdomen,
one of which we have already observed. These little organs are
used as paddles, and assist the crayfish in moving through the water ;
but the creature spends its time chiefly on
the bottom, and the five pairs of legs are by
far the most useful organs of locomotion.

When examining one of the abdominal
segments, we observed that the dorsal plate
extended downward on each side below its
junction with the ventral plate. Now it will
be’seen that the same arrangement obtains
in the thorax, where a cavity is formed along
each side of the body, between the prolonged
dorsal plate and the side of the thorax, \
which is enclosed by the bases of the walking YA
legs. .

Within this cavity are the plumelike
gills, attached in part to membranes between
the limbs and the body wall, and in part to
the bases of the limbs themselves.

Water can pass freely through this
chamber, thus bathing the gills, and pro-
moting the exchange of gases that constitute :
the process of respiration. And since some te er
of the gills are attached to the bases of the i eed its
limbs, every movement of the latter must Ginx (7) ATTACHED
assist the breathing by promoting the circu-
lation of water in the gill chamber. Further, the thin broad plate of
the second maxilla, to which we have already referred as lying
within this chamber, is always moving backwards and forwards,
bailing the water out at the front opening at every forward
movement.

This movement can be easily traced in a living crayfish as
you hold it in your hand, the outer wall of the gill chamber being

188 LIFE IN PONDS AND STREAMS

generally sufficiently transparent to enable the movements of this
organ to be distinctly seen.

Although the crayfish is a gill-breathing animal, it can live for
a long time out of water, provided the atmosphere around it is cool
and moist; but the gills become absolutely useless when dry.

The internal anatomy of the crayfish reveals many points of
interest even to a beginner, and much may be made out by the aid
of simple dissections such as could be accomplished by any one.
The specimen chosen for dissection should be fresh, and if it is
found to be necessary to kill one for the purpose, this may be done
expeditiously by giving it a momentary immersion in hot water;
or a specimen that has been preserved in spirit will answer very
well.

In any case the dead animal should be pinned out in a shallow
trough of water, the pins being secured in a layer of wax that has
been previously melted and run into the trough, or in a sheet of
cork weighted with lead. Such an arrangement may seem un-
necessary to a young anatomist, but he will soon learn to appreciate
the value of this method of conducting a dissection if he will only
compare his results obtained both with and without the use of
the trough. With its use the soft parts are well displayed, and
an occasional change of water as it becomes turbid will keep his
work beautifully clean.

The top shell of the crayfish may be removed by carefully cutting
it away with a finely pointed pair of scissors, care being taken not
to allow the instrument to damage the internal organs.

By this simple process we expose the whole of the digestive tube,
including the large stomach in the thorax, and the straight intestinal
tube running through the abdomen.

The stomach consists of two distinct parts—a large chamber in
front, and a smaller one behind it; and if the organ be opened care-
fully it will be noticed that parts of it are of a hard bony structure.
It contains, in fact, several little ossicles which are actuated by
muscles, and thus constitute a very effective apparatus for the
mastication of food.

The same dissection also reveals the heart, which is a five-sided
organ, situated about the middle of the thorax; the digestive gland,
a yellow pulpy organ which prepares a digestive fluid; also a
pair of green glands, lying beneath the front of the stomach, which
separate waste products from the blood, and correspond with the
kidneys in vertebrate animals.

FRESHWATER CRUSTACEANS AND SPIDERS 189

In addition to these structures we observe the organs of re-
production, and the mass of white flesh which forms the powerful
muscles of the abdomen.

And now we must note the position of the nervous system,
which is very different from that of the vertebrates. In the latter
the central or chief part of the nervous system lies down the middle
of the back, near the dorsal surface, and is usually protected by a
bony tube; but in Crustaceans we find it lying along the middle of

da hog h mg li s

— {Py i
\ Oy je | : o “ye Sn
5 PMLINNNS sil Yy k

Fic. 174.—\LoneirupInaL SECTION OF THE CRAYFISH

a, anus ; d.a, dorsal artery ; #, heart ; /.g, intestine or hind gut; &, kidney ; Z.a, labrum
or lip; li, liver; m.g, mid gut; n.c, nerve chain ; s, stomach; s.a, sternal artery ;
v.a, ventral artery

the ventral surface, and occupying the same cavity as the organs of
digestion and circulation. In order to display it we must remove
all the latter, and very carefully pick away the muscles at the bases
of the appendages and the mass of flesh that fills the abdomen.
This being done, we see the chain of nerve ganglia and the delicate
white nerve threads which unite them.

We have previously noted the position of the gills. These organs
are necessarily richly supplied with blood sent to them for aération.

190 LIFE IN PONDS AND STREAMS

The aérated blood is then conveyed to the heart by means of several
vessels, and the contraction of the heart propels it to all parts of the
body. The circulation continues for a time ina crayfish that has
been killed, and if it is opened shortly after it is dead the contraction
of the heart may be observed.

The organ which serves the purpose of an ear is situated in the
first joint of the small antenne. It is a simple little pouch con-
taining grains of sand, and is surrounded with minute branches of
the auditory nerve.

The antennules are also the seat of the sense of smell; at least,
it is in these appendages that we meet with little organs that are
supposed to have an olfactory function. There are many other
points of interest which the student may observe in the structure of
the crayfish.

Like most other Crustaceans, crayfishes have the remarkable
power of reproducing lost limbs. It is a very common thing to meet
with some that have one or more limbs smaller than the correspond-
ing ones of the opposite side. These are new limbs that are growing
in the place of some that have been lost either in combat or during
struggles to escape from an enemy.

An injured limb is always cast off at a joint above the seat of
injury, and, in the case of the clawed legs, usually at the narrowest
joint. Thus the injury is transferred to a point where the soft
structures are constricted, so that there is not only less danger of
the animal bleeding to death, but the soft parts close over and heal
much more rapidly. ‘The new limb formed eventually becomes as
large, or nearly so, as the original.

In the fall of the year the body of the female crayfish contains a
large number of dark-coloured eggs, which, when laid, are covered
with a gelatinous substance ; and this substance not only causes the
eggs to adhere to the swimmerets of the parent, but soon hardens
and forms a number of little stalks by which they remain perma-
nently attached.

The young are hatched early in the following summer. They
are then little semi-transparent greyish creatures, rather less than
a quarter of an inch in length, and still cling by means of their claws
to the gelatinous matter that formerly supported the eggs.

Soon, however, they detach themselves from the parent, but
remain so near her that they can readily fly to her for protection in
times of danger. After a time, however, they stray away and shift
for themselves.

FRESHWATER CRUSTACEANS AND SPIDERS 191

At first they grow very rapidly, and attain a length of about an
inch and a half during the first year, but after that the growth is
less rapid, being rather less than an inch a year till the time that
they reach maturity at the age of four or five years.

At this period they are nearly five inches in length, but the males
are usually a little longer than the females, and the bodies of the
latter are considerably broader.

The growth of the crayfish is not regular, but takes place rather
rapidly at certain short intervals following the moults, or casting of
the skin; and these intervals are necessarily shorter during the
more rapid development of the young, occurring about three times
during the course of the first year, and about once a year after.
Although we use the term ‘ casting of the skin,’ it must be remem-
bered that the skin is not entirely shed, but only the outer and
hardened layer or epidermis.

When the time arrives for the moult the creature struggles
vigorously within its case, every limb and even every appendage
taking part in the action. Thus each part is loosened within its
shell, even to the eyestalks and the slender antenne, and is gradually
pulled towards the middle of the body. Then the membrane
between the thorax and the abdomen breaks away on the upper side,
the hardened integument of the libs is split, and the creature
struggles till it has completely freed itself from its old coat, which
retains its perfect form after having been vacated.

Now, though its body is firm, the newly exposed skin is soft
and yielding, and remains so for a few days, during which time the
creature grows rapidly. Then the new skin gradually hardens by
the deposition of carbonate of lime, and the growth is arrested till
the time of the following moult.

It not unfrequently happens that one or more of the limbs break
off during the creature’s struggles to release itself from its old coat,
but, as we have already learnt, these limbs are replaced by new
growths. Further, the moulting periods are times of great danger,
for not only is the crayfish liable to be injured by enemies which
could do it no harm while it was covered by a calcareous armour,
but it sometimes succumbs from the effects of the violent struggles
necessary to set itself free. It is interesting to note, too, that the
hardened lining of parts of the digestive tube is also cast off at the
same time as the outer skin; but this is gradually dissolved in
the creature’s stomach, and undoubtedly helps in the building up of
the new armour.

192 LIFE IN PONDS AND STREAMS

The Freshwater Shrimp (Gammarus pulex) is another very
common crustacean, to be found in abundance in almost every
stream and ditch. It isfar more lively than the crayfish, and swims
about very actively with a jerky motion. As a rule it keeps near
the bottom, or rests on the stalks of sub-
merged leaves, and feeds on all kinds of de-
composing organic matter, both animal and
vegetable.

Like the carrion beetles on land, it will
swarm round the decomposing body of a dead
animal, devouring it greedily ; and when such
feasts are not in its way, it will turn its atten-
tion to decaying vegetation. Hence, like all
carrion feeders, it performs a very useful
work in disposing of those matters which
would otherwise become putrid and poisonous:

Fic. 175. : :
Tue FRESH- and pollute either the water or the air.
WATER SHRIMP It thrives well in the aquarium, especially

when that aquarium is so badly managed as
to allow the food it requires to accumulate; but it cannot be kept
in company with carnivorous insects and fishes, many of which
feed on it. The River Bullhgad is very partial to it, and the little
Stickleback, though it does not seem to be able to swallow a
full-grown Gammarus, will nevertheless chase it about in a most
amusing manner.

The Freshwater Shrimp belongs to the section of Crustaceans
called Edriophthaima or Sessile-eyed Crustaceans, its eyes, though
prominent, not being mounted on moveable stalks like those of the
Crayfish. The section is also spoken of as the T'etradecapoda or
Fourteen-footed Crustaceans, while the Crayfish belongs to the
Decapoda or Ten-footed Crustaceans.

Its body is greatly curved, and its limbs are turned in all direc-
tions, and are used for walking as well as for swimming.

It breathes by means of air sacs, which are surrounded by blood-
vessels and connected with some of the limbs.

Other Freshwater Crustaceans, belonging to the same order, are
parasites, living on the flesh of fishes and other aquatic animals, to
the outer surface of which they attach themselves.

There is another division of the Crustacea termed Isopods—a
word which signifies ‘ equal-footed,’ but yet the legs are not always
equal in size, nor are they all of the same build. This division

.

FRESHWATER CRUSTACEANS AND SPIDERS 193

includes the well-known wood-lice that hide under stones and in
rotting trees. It also includes aquatic creatures, of a very similar
appearance, that belong to the family Asellide.

One of them, Asellus aquaticus, is exceedingly common in most
of our ponds, where it may be found creeping on the bottom or on
submerged weeds. It is about half

an inch in length, but the male is \ y,
larger than the female; and it is ae a
popularly known as the Water-hog . e
Louse. ~y Y A

The body is rather flat, and is ma:
made up of nine segments, the first amt =

of which is the head, the last one ce Sa 2
\

op
the abdomen, while the intermediate say ibs wt

seven segments are all regarded as
belonging to the thorax. The seg- SSA
mentation too is very distinct, the
body being very deeply divided at
the joints. It has long appendages
at the tip of the abdomen, and
the thoracic segments bear walking
limbs.

The Water-hog Louse is perfectly
harmless in the aquarium, and since

it feeds almost entirely on decom- Fic. 176.—Asellus aquaticus
posing organic matter it may even
prove more or less useful as a scavenger. Like the Freshwater

Shrimp, its eyes, which are compound, are not mounted on move-
able stalks.

The water from almost every pond or ditch contains little crus-
taceans, some so small as to be almost invisible to the naked eye,
swimming about actively with a very jerky motion. ‘These are
commonly called Water Fleas, but they include a considerable
variety of creatures which are not closely related to the true fleas.

Some of them belong to the genus Daphnia, which includes
about seven species. In these the carapace is of such a form as to
resemble the shell of a bivalve mollusc. It is also so transparent
that the whole of the internal organs can be seen most distinctly
within it. The abdomen is rudimentary, and is capable of being
withdrawn within the carapace.

The compound eyes are represented by a single spherical struc-

O

194 LIFE IN PONDS AND STREAMS

ture, the cornea of which is composed of many facets or lenses.
The jaws are strong and armed with spines, and the front of the
carapace terminates in a prominent beak.

The antennz are very large and powerful, and form the chief
means of locomotion; but the
antennules are small and rudi-
mentary.

Water Fleas belong to the
division Branchiopoda or Gill-
footed Crustaceans, so called be-
cause the breathing organs are
attached to the limbs.

They are most active when
the sun is low, both in the
morning and the evening, when
they are continuously jerking
about among the water weeds
or playing just under the sur-
face; but during the heat of the
day they settle on the muddy

Pigsa77 Wits es bottom, often in such vast num-

(Daphnia pulex), MAGNIFIED bers as to give a decided colour

to the water.

The male is much smaller than the female, and is comparatively
rare. In fact it is never to be seen at all except at certain seasons.

After the eggs are laid they are retained by the female in a space
between the side of the carapace and the body, and there they are
held until the young are perfectly formed.

Pond water also abounds with little pear-shaped creatures be-
longing to the genus Cyclops. These are often called Water Fleas,
for they swim about with a series of sudden jerks much in the same
way as the Daphnia, and they also resemble the latter in many
respects.

The body of Cyclops is flattened on the ventral and convex on
the dorsal side. The head and thorax form the larger part of the
body, and the carapace which covers this part terminates in front
in a curved rostrum.

The antennules are large and strong, and form the chief means
of locomotion, being used after the manner of oars; the antenne
are much shorter than these. ®.

The eyes are both fused into one dark mass of a globular form

FRESHWATER CRUSTACEANS AND SPIDERS 195

in the middle of the forehead, a feature which has suggested a
resemblance to the one-eyed giants of Greek mythology. Hence
the animals in question are termed Cyclops.

The mouth is provided with a pair of mandibles, and the fore-
most appendages of the thorax are two pairs of large and strong
foot-jaws, while the others are paddle-like organs which assist in
the movements of the animal, and are used like oars,

Fic. 178.—Cyclops quadricornis,
FEMALE CARRYING THE EGG SACS.
Aso THE LARVA, MAGNIFIED

Fie. 179.—A Cyclops viewED
FROM THE SIDE

Behind the cephalo-thorax there are four moveable segments,
behind which the abdomen is enlarged; and then follow other seg-
ments which taper off towards the extremity.

Attached to the enlarged portion of the body of the female there
is a pair of large pear-shaped egg sacs, in which the eggs are carried
till the young are hatched. At first these young are very unlike the
adult, but they undergo a series of metamorphoses like the larve of
insects.

The male is much smaller than the female.

AQuATIC SPIDERS

The spiders possess certain characteristics in common with
crustaceans. Like them their bodies are made up of two distinct
parts, the foremost of which is the combined head and thorax, and
the other the abdomen; but the latter is generally united to the
former by means of a very slender stalklike waist, and is not
segmented like the corresponding part of the crayfish, nor does it
bear any limbs,

02

196 LIFE IN PONDS AND STREAMS

As we commonly hear spiders spoken of as insects, it may be
well here, as we enumerate the chief points in their general struc-
ture, to call attention to certain important differences between the
Arachnide and the Insecta, which, as we have
already seen, belong to two distinct classes of the
Arthropoda.

In the latter, it will be remembered, the head
is quite distinct from the thorax, and often united
to it by an exceedingly narrow neck.

The abdomen of spiders is very variable in
form, being globular, egg-shaped, cylindrical, or
even triangular.

The walking appendages are eight in number
(in insects always six), and are all attached to
the thorax. They are built up on the same plan
as the legs of insects, each leg consisting of seven
parts. The first of these is the hip or cova,
followed by the trochanter and a robust femur or thigh. ‘Then
come the tibia or shank, represented by two joints, and the tarsus
or foot which terminates in powerful claws.

Unlike both crustaceans and insects, spiders have simple eyes,
and these, usually eight in number, are situated on the front of the
upper surface of the head. The arrangement of these organs is
very variable, but they are commonly placed in two transverse

Fig. 180. — Lee
OF A SPIDER

rows.

Above the mouth there is a pair of powerful forceps or falces,
by means of which the spider seizes and holds its prey. Each of
these consists of two joints, the first of which is stout and grooved
along the inner side. The second is slender, and terminates in a
sharp point. It is also traversed by a canal which opens at the tip,
and communicates with a poison-secreting gland in the first joint.
When the falces are not in use the second joint folds into the groove
of the first, just as the blade of a clasp-knife folds in the handle. It
will thus be seen that the falees are merely organs of prehension,
with the power of poisoning the prey, and are not concerned with
feeding in any way, as are organs of a similar build in certain
aquatic insects; yet they are often spoken of as mandibles.

Below the falces is a pair of maille or lower jaws, which are
composed of five joints, and are developed to such an extent as to
resemble a pair of legs, for which they may be easily mistaken by
those not acquainted with the structure of spiders. The organs in

FRESHWATER. CRUSTACEANS AND SPIDERS 197

the mouth are not conspicuous, being enveloped in a sheath, as we
shall presently observe is the case with many insects.

The spinning organs, or spinnerets, constitute one of the most
interesting features of spiders. These are situated at or just under
the tip of the abdomen, and are either two, four, six, or eight in
number, and mounted on wartlike prominences.

Each spinneret is perforated with a number of minute holes,
from which issue as many delicate threads of a viscid substance,
and these all unite to form a single thread, which hardens into a
kind of silk almost immediately on exposure to air. The fluid itself
is prepared by the silk-glands, which lie in the abdomen, and com-
municate with the spinnerets by means of fine ducts.

We have now to note one or two of the chief features in the in-
ternal anatomy of the spider, and first we will briefly examine its
breathing apparatus. In the front portion of the abdomen there
are two or four air sacs which serve the purpose of the lungs of
higher animals, since the blood circulating round them is aérated
by the absorption of air obtained direct from the atmosphere.
The air is admitted into the air sacs through slitlike apertures
which may be seen on the under side of the front part of the
abdomen.

In addition to these organs the spider possesses a system of
trachez or air tubes, which communicate with the exterior by two
openings either near the air sacs or at the tip of the abdomen.

The digestive tube of the spider is short, and the stomach, which
is a hollow ringlike organ, gives off a number of radiating blind
tubes.

The blood is colourless, and is propelled by a four-chambered
heart situated in the abdomen. The chambers are arranged longi-
tudinally in a single line, and the blood is received behind, and then
propelled forwards into the arteries which carry the fluid to all
parts.

It will be remembered that some of the crustaceans and most
insects undergo metamorphoses, so that the young are very different
from the adults in form. This is not the case with spiders, the
young, just_having issued from the egg, being of the same form and
build as the adult. Further, unlike insects, but like some of the
crustaceans, spiders continue to moult after having reached the
adult stage.

Spiders are usually divided into two main groups, the Six-eyed
(Senoculina) and the Eight-eyed (Octonoculina). Most of the

198 LIFE IN PONDS AND STREAMS

British species and all our aquatic ones belong to the latter, of
which there are several families.

The common Garden Spider belongs to the family Epetride, in
which the eyes are arranged with a square of four eyes in the
middle of the forehead and two oneach side. The legs are long and
stout, the third pair being shorter than all the others. The abdomen
is large and generally oval or globular, and there are three pairs of
spinnerets.

All the Epeiride construct snares to entrap their prey, and most
of them are of terrestrial habits; but afew species are likely to come
in the way of the pond-hunter, as they spin their webs among
aquatic plants, and prey almost entirely on aquatic insects. None,
however, actually live in water.

The pet spider of the student of pond life is undoubtedly the
Water Spider (Argyroneta aquatica), and the habits of this creature
are so interesting that it has attracted a great deal of attention for
along time. It belongs to the family Drassid@, the members of
which are distinguished by an oval abdomen, and eyes arranged in
two curves which are convex towards the front of the head.

Although an air breather, obtaining its air direct from the
atmosphere, yet it spends the greater part of its existence beneath
the surface of the water, and is very commonly to be found among
the contents of the pond-hunter’s net. Still it seems quite at home
when on land, and it often leaves the water to search for prey
among the vegetation of the banks. In this case, however, it
seldom devours its captives on land, but carries them away to its
aquatic home, where it will even store up food for a future day.

Its abdomen is covered with a very fine downy hair which the
water cannot penetrate; hence when it dives or walks down the
stems of aquatic plants it is covered with a layer of air which gives
it the appearance of a moving globule of silver.

This air is of course necessary for its respiration, but is not
sufficient to satisfy its wants for any great length of time; there-
fore the creature must either make frequent visits to the surface to
renew its supply, or it must in some way or other lay up a store of
air beneath the surface.

Now, both these alternatives are resorted to by Argyroneta at
different times, and its method of conducting the latter is exceed-
ingly interesting. It constructs a silken cell like an inverted cup,
and moors it by threads of the same material to the stems and
leaves of submerged plants. Having finished this portion of its

FRESHWATER CRUSTACEANS AND SPIDERS 199

work, it makes several visits to the surface, each time returning to
its cell with a fresh supply of air entangled among the hair of its

ong
Ti
‘wit

son onnn youn gun tg eMAERAELARLAELAT OAL

mr
somone ert)

TT

SRT Lo

Fic. 181.—Argyroneta

aquatica ANP ITs NEstT

abdomen, and allowing a portion of this air to rise into its inverted

silken cup. In this way it stores

up sufficient air to enable it to

200 LIFE IN PONDS AND STREAMS

rest below the surface for some time without the necessity of paying
further visits to the top.

It further utilises its little home as a nursery for its young, for
the female places within it the little silken cocoons in which she |
encloses her eggs, and these she watches closely till the young
ones are hatched. During the winter months itis far less active ; in
fact it shuts itself up within the cell when the cold weather arrives.

Argyroneta is about half an inch in length, but the male is
larger than the female. I strongly advise the reader to capture
a few in order that he may watch their interesting proceedings ;
but they must have plenty of room, a good supply of weeds, and
must be fed regularly with insects. It must be remembered too
that many carnivorous aquatic creatures prey on water spiders, and
several of the larger insects are among their enemies.

Another family of spiders—Lycoside—have aquatic, or rather
semi-aquatic, representatives. They run on the surface, or live
almost exclusively on the banks of ponds and streams, and prey
largely on aquatic insects. 5

The members of this family may be known by the arrangement
of the eight eyes, of which four are placed in a row in front, and
the remaining four, which are larger, in the form of a square be-
hind them. The abdomen is oval, and the third and fourth pa‘rs
of legs are shorter than the others.

One of them, Dolomedes fimbriatus, is a very pretty creature,
its hairy brown body being marked with yellow. It measures nearly.
an inch in length. It chases its prey on the surface of the water,

but runs on the floating leaves of
water lilies and other plants more

: N i ij J than on the water itself, and is
SS i found principally in the. sluggish

GZ 77 wl streams of the fens.
A x Other smaller species of this
Gf i, \ | family are similar in habit, and one
ff x ; : dill | or two of them even dive below the

: I 1 ‘ | surface when threatened from above.

=A Finally, a brief reference must

Fic. 182.—A Warer Mire — be made to the Water Mites, which

(Hydrachna), MAGNIFIED belong to the same class as spiders.

Of these there are several species,

varying much in size ; some being almost microscopic, while others
are nearly a quarter of an inch in length.

FRESHWATER CRUSTACEANS AND SPIDERS 201

The species figured belongs to the genus Hydrachna, some ot
the members of which are very common in our ponds, where they
swim about steadily by the rapid movements of their fringed legs.
They undergo metamorphoses when young, and it is a curious fact
that the larva has only six legs, while the adult has eight.

Most Water Mites seem to have a remarkable power of resisting
the action of certain powerful substances. I once placed a number
of them in a small tube of fifty per cent. alcohol, and then hermeti-
cally sealed the tube. After this was done I was surprised to see
the mites swimming about, apparently with as much comfort as
when they were in water ; and nearly two hours had elapsed before
they ceased to show signs of life.

202 LIFE IN PONDS AND STREAMS

CHAPTER X
AQUATIC INSECTS

No part of the pond-hunter’s work could possibly be more interesting
than the observation and study of aquatic insects; for not only are
these creatures generally very active in their movements, and the
movements also extremely varied, but most species exhibit marked
changes in structure and habits as they develop ; and, moreover, the
number of species is so large, and their distribution so wide, that
insect life is rarely wanting among the takings of the net, but often,
if not generally, forms the most prominent feature.

And it is not only in ponds that we find insect life predominat-
ing above all other forms. Every stream, even to the impetuous
mountain torrent, has its insect population. The air literally
swarms with them except in the coldest climes, and there are
many species which retain their activity in the season of biting
frosts. The soil harbours its thousands ; myriads seek their food on
all kinds of vegetable life ; some bore into the very heart of trees ;
and others live in the blackest atmosphere of caves. Brackish
tidal waters often teem with them, and even the sea has its own
particular species from this extensive group.

Insects have been assigned a place at the very head of the
invertebrates. They are mostly of small size, the largest of them
being much inferior in this respect when compared with many of
their crustacean cousins. Like the latter, they exhibit a very
complicated external framework, with highly developed appendages,
some of which give them a most amazing power of locomotion. The
internal anatomy too points to a high position in the scale of life ;
but it is the superior intelligence displayed by a large number of
species that awards them the place of honour at the summit of the
scale of the invertebrate sub-kingdoms.

The term ‘ insect’ signifies ‘ cut into,’ and at once points to the
most obvious characteristic by which the creatures of this sub-

AQUATIC INSECTS 203

kingdom are to be distinguished from those of all the others, for the
body of an insect in its perfect state is usually divided by distinct
constrictions into three main parts—the head, the thorax, and the
abdomen ; and the constrictions are often
so deep that the head is joined to the
thorax by a very narrow and almost
threadlike neck, or the abdomen con-
nected with the thorax by an equally
slender waist.

All three of these divisions are further
divided into ringlike segments, often very
indistinct in the foremost divisions, but
usually well marked in the abdomen.
Several of the segments bear each a pair
of appendages, as we observed was the
case with the crayfish and the freshwater
shrimp; and where no external line of
division is visible between the segments,
the pairs of appendages without, and the
arrangement of nerve ganglia within, both
aid us in mentally separating those which
have become so far fused together as to
obliterate the external lines of union.

Thus the head of an insect is regarded
as being made up of from four to six or
more segments. The thorax consists of

Fic. 183.—Bopy or An

three segments, each of which bears a pair INSECT, UNDER SIDE
of legs. The abdomen is of eight segments, a, antenne; »b, tarsus: ¢,
= : relics - . tibia; d, femur; e, palpi;
none of which have true walking limbs ; A okra anes cs
and to these are often appended two or abdomen, with segments

nee numbered
three others, more or less modified, and

forming together what is known as the post-abdomen.

As already stated, insects undergo marked changes in form and
structure during their growth and development. In most cases the
changes are two in number, so that they exist in well-defined forms,
known respectively as the larva or grub, the pupa or chrysalis,
and the imago or perfect insect. We shall first note the general
structure of the perfect form, and then pass on to an observation of
the earlier stages, and of the metamorphoses through which the
insect passes during its development.

The head of the perfect insect bears a pair of antenne, each of

204 LIFE IN PONDS AND STREAMS

which is made up of a number of joints like the antenne | of:
crustaceans. These appeadages are sometimes simple, and either
pointed or thickened at the
extremity ; sometimes they are
pectinated or comblike, or the
tip may be furnished with a
number of flat leaflike plates.
They are the organs of touch

to some. investigators, are also
the seat of the sense of smell.
In some insects, too, they are
undoubtedly a means of com-
munication.

The eyes are usually large,
and compound like those of
crustaceans, each filament .of
the optic nerve having its own

Fic. 184. -THe STAGES OF AN

‘1G. 185.—SEcTION OF THE
INSECT Fie >

Eve or AN _ INSECT,
a, larva: b, pupa ; c, perfect insect MAGNIFIED

crystalline cone, pigment sheath, and facet of. the cornea. . The
number of cones is often very large —over two thousand in the: eye
of the common house-fly, and from twenty thousand to near thirty
thousand in the eyes of dragon flies. ANS

The mouth is situated on the under side of the front of the head,
and varies considerably in structure-according to the habits of the
owners. There are two lips, the upper or labrum, and the lower or
labium ; and between them, in many species, lie two pairs of jaws
which move horizontally.

The labia correspond with the second pair of jaws in the cray-
fish, but are usually united in insects. ‘They bear a pair of feelers
which are called the labial palpi.

AQUATIC INSECTS 205

In cases where the jaws are well developed the upper pair
(mandibles) is used for biting, and the lower (masrill@) for chewing ;
and the latter, like the labium, bear another pair of feelers, which
are termed the maxillary palpi.

These biting and chewing organs, however, undergo strange
modifications in the different orders of insects. In butterflies and
moths, for example, they are not in the least adapted for the
division of solid food, but form a long tube through which these
insects suck the sweet juices on which they feed.

In these insects the maxille are long and slender, and each one
is grooved throughout its length, and shaped in such a manner that
when the two are brought into apposition they form a long tube.
Each maxilla too contains a second tube, running parallel with
and just beneath its groove; and thus a transverse section of the
compound structure, which is called the proboscis, reveals three
distinct tubes, one of which is central, and the other two lateral,
This proboscis is retractile, and, when not in use, is neatly coiled
into a close spiral which lies partially concealed between the two
large labial palps.

In some of the Hymenoptera the upper lip and the mandible are
both adapted for biting solid substances ; while the lower lip and
the mavxille are grooved like the latter organ in butterflies and
moths, so that they form a sucking tube when brought into appo-
sition.

In the common house-fly we see another interesting modification
of these appendages of the mouth, for here the labium forms a
sheath, within which the mandibles and the maxille, both reduced
to a simple bristle-like form, are encased.

These are only a few of the wonderful modifications of the
mouth appendages of insects, and others will be dealt with when we
come to examine the structure of the aquatic species which more
directly concern us; but we must now pass on to the structure and
arrangement of the limbs.

These consist of three pairs of legs, and usually one or two
pairs of wings; but it must be remembered that the latter are not
limbs in the strict morphological sense of the term, being merely
modified extensions of the body wall, supported and strengthened
by ribs or rays of a horny substance, about which I shall have
some remarks to make presently.

One pair of legs is attached to each of the three segments
of the thorax. Each consists of five distinct parts, covered with

206 LIFE IN PONDS AND STREAMS

a hard chitinous exo-skeleton like that which surrounds the

body.

The basal joint is the hip or cora, beyond which is the short

ringlike trochanter.

1G. 186.—LEG or AN
INSECT
a, tarsus; 0b, tibia; c,
femur; d, trochanter ;
2, coxa

The third is the thigh or femur, the fourth
the shin or tvbia, and the last the foot or
tarsus.

The last named is made up of several
small joints, varying in number, and usually
terminating in a claw or claws, frequently
with broad discs which enable the insect to
adhere by suction.

The accompanying woodcut gives an idea
of the general structure of the leg of an
insect, but of course we shall be prepared to
meet with many interesting and peculiar
modifications in the arrangement, joints, and
form of the limb in the various aquatic species
which we shall examine.

When the winged insect has just com-

pleted its final metamorphosis the wings are soft, and often more
or less folded. Soon, however, they will have developed to their
full dimensions, and shortly after will be dry and rigid and adapted

for flight.

Fic. 187.—W1nG oF AN INSECT, SHOWING THE Rays oR NERVURES

Each wing consists of a membrane, usually thin and transparent,
sometimes quite naked, but often clothed with minute scales or a
soft hair. In some instances, however, the fore pair are wholly or

AQUATIC INSECTS 207

partially composed of a hard horny or chitinous substance, in which
case they are not adapted for flying, but merely serve as a protection
for the hindermost membranous pair, which are folded up beneath
them.

Thin membranous wings are always supported by hollow rays
(ribs or coste) of a chitinous material, which give the necessary
rigidity to the whole structure without materially adding to the
weight. These at first—that is, immediately after the emergence
from the pupa case---contain fluid ; but within the rays are branches
of the trachee or breathing tubes, which contain nothing but air
after the wings are dry.

The arrangement of the wing rays of insects is very varied, some
wings being supported by only a few, while others have an exceed-
ingly fine and almost invisible network; and the disposition of
these rays is a matter of considerable importance to the student of
insect life, since it forms an important basis of classification, not
only for the main groups, but also for minor subdivisions of these
groups.

When examining the external structures of insects we usually
observe small openings in the sides of several of the segments.
These are called spiracles or stigmata, and are the openings of the
main air tubes (tracheal trunks) which branch off into smaller
tubes (¢trachew) within the body.

The number of stigmata varies greatly in different insects.
Frequently there are nine pairs, but in some insects there are only
two or three; and in some of the aquatic larve the number is
reduced to a single pair.

As a rule there are none in the head, one or two pairs in the
thorax, and several pairs at the sides of the abdominal segments,
either on the segments themselves or between them. But we do
not always find the stigmata at the sides of the body. Sometimes
they are situated on the dorsal surface, or the extremity of the ab-
domen, or even on the ventral surface. And as it happens that
these interesting modifications occur principally in the aquatic
species, we shall have favourable opportunities of dealing with them
in the present chapter. Many aquatic larve too, though possessed
of well-developed trachew, have no stigmata, but the branches of
the trachew ramify into leaflike or fringed appendages, through the
very thin walls of which dissolved oxygen is absorbed from water
while the animals are submerged, and carbonic acid gas is at the
same time given off in exchange. Again, some of these larve,

208 LIFE IN PONDS AND STREAMS

particularly those of certain dragon flies, though they are provided
with stigmata in the thorax, do not appear to make use of these
openings, but receive their oxygen and give off carbonic acid gas from
and to water which is periodically drawn into and expelled from the
enlarged terminal portion of the digestive tube, on the thin walls of
which the finer divisions of the tracheal system are distributed.

The stigmata of insects are not permanently open, but are pro-
vided with a valvular lip by which the opening may be more or less
perfectly closed at will. The movements of the lip are produced by
the contraction of a special muscle, and, on the subsequent relaxa-
tion of this muscle, by the elasticity of the chitinous edge which
extends round one half of the stigma.

The main tracheal tubes which start from the stigmata soon give
off branches, and these further divide and subdivide within the

body of the insect, thus

forming a complicated

system of air tubes by

l which the blood is aérated,

ic the exchange of gases

Fic. 188.—Tracuea or Insect, suowrne taking place through the

THE SPIRAL THREAD extremely thin mem-

branous walls. As a rule

the branches of each tracheal trunk unite with those of the next, so

that each segment of the body is almost equally dependent on all

the trunks; and frequently we find all the main tubes of each

side connected by a wide longitudinal trunk, and, further, the

main trunks of one side are often connected with the corresponding
ones of the opposite side by means of wide transverse tubes.

It is absolutely necessary that the walls of the tracheal tubes
should be so thin as to allow the exchange of gases to take place
with freedom, and at the same time they should be sufficiently
rigid to retain their circular section for the easy passage of air
throughout the system. It is further necessary that these walls be
sufficiently elastic to regain their normal form after having been
altered by the muscular movements of the insect. All these con-
ditions are fulfilled in the structure of the trachew, for their thin
membranous and easily permeable walls are supported by a coiled
elastic chitinous fibre, the arrangement and use of which remind
us of the coil of wire that supports an indiarubber gas-tube.

Every muscular movement of the body of an insect probably
does more or less to promote air currents in the tracheal system,

AQUATIC INSECTS 209

but insects are capable of special motions by which air may be
rhythmically inhaled into and expelled from the air tubes. If
you attentively watch a dragon fly-—Platetrum depressum answers
admirably for the purpose—at rest, you will observe that the
abdomen is considerably flattened at intervals by the* approxi-
mation of the dorsal and ventral walls. Such a movement will of
course compress the tracheal tubes more or less, and thus cause
air to be driven out through the stigmata, providing they are open;
while the opposite movement, which immediately follows the com-
pression of the abdomen, allows the trachex to recoil by their own
elasticity, thus reducing the air pressure within, and causing air to
rush in from without.

. There is yet another means by which air is set in motion in the
trachee. The abdominal segments of insects are generally con-
structed in such a way that each one is capable of sliding more or
less with a telescopic movement within the one in front of it, thus
considerably shortening the body, which can afterwards be as easily
elongated by the action of an antagonistic set of muscles. And
these movements, again, by alternately enlarging and reducing
the size of the abdomen, cause air to enter and leave the tracheal
tubes.

The digestive organs of an insect usually consist of a mouth,
esophagus or gullet, stomach, and intestinal tube.

In some larve which subsist on liquid food derived by suction
there is no mouth, but canals or grooves convey the nourishment
from the tips of the mandibles direct into the cesophagus. Some
perfect insects too, and notably the Ephemerida, have no mouths.
These live for an exceedingly short time in the adult form, some-
times only a few hours, and consequently require no food.

_ Butterflies, and other insects that subsist entirely on liquid food,
while in the perfect form are provided with a special stomach
for suction only. This is a thin-walled bag which opens into the
esophagus, in front of the true digestive stomach. In others,
which feed on solids, there is a gizzard with a number of horny
teeth for mastication. ‘

The glandular or digestive stomach is followed by the intestine,
which is usually short in those species which feed on liquids or on
solid animal matter, but longer in the case of those which subsist
on solid vegetable matter.

The heart is a flattened tube lying along the middle of the back,
just beneath the skin, and may be seen pulsating in those insects in

P

210 LIFE IN PONDS AND STREAMS

which the dorsal skin is transparent. It consists of a chain of
chambers, separated by valves, and closed behind. It gives rise to
only one vessel, termed the aorta, which proceeds forward from the
front extremity; but there are several pairs of openings along the
sides. The heart receives the impure blood from the different parts
of the body, together with newly formed blood and nutritious matter
from the digestive tube. These are then propelled into spaces
between the tissues, thus nourishing those
tissues, and also in part becoming oxy-
genated and freed from carbonic acid gas
by contact with tracheal tubes. In most
insects the blood is colourless, but it is
frequently yellow or green, and less com-
monly of a reddish colour.

The nervous system is very similar
to that of the crayfish. There is a large
ganglion in the head, supplying nerves
to the antenne and the eyes. Three
double ganglia in the three segments of
the thorax supply the limbs; and behind
Fic. 189.—Nervous Sys- these lies a chain of ganglia in the abdo-

TEM oF AN IysEcT men, one ganglion in each segment.
(BEETLE), SHOWING a The sounds produced by insects are
tS Aa IETS, sometimes brought about by the vibration
NERVE CORD of little projections of a horny material
within an enlarged tracheal trunk. This
seems to be the case with the buzzing of flies. But they are
apparently more generally produced by the friction of two hard
parts of the skin which are provided with minute ridges or tooth-
like projections. Thus in the grasshopper the femur of the third
leg rubs against a ridge on the front wing ; in crickets the two
outer horny wings are rubbed together ; and in certain beetles the
hind leg is rubbed against the side of the abdomen.

Those insects which produce sounds are usually provided with a
special auditory apparatus in addition to that in the antenne, and
this is situated on the tibie of the forelegs.

Another interesting feature in the structure of some insects is
the presence of an organ that is capable of emitting rays of light.
This, in the case of the glow-worm, the only British luminous
insect, is a whitish organ, situated under the last three segments of
the abdomen, and very plentifully supplied with nerves and trachee,

AQUATIC INSECTS 211

We must now pass on to the consideration of the changes which
insects undergo during their growth and development, confining
our attention at present to those whose metamorphoses are
complete.

The eggs are laid by the female on or near the food required by
her offspring. They are often arranged in some definite order, and
the shells are frequently beautifully sculptured. The female is often
provided with an apparatus by which the eggs can be deposited
in crevices, or by means of which they may be thrust into animal
or vegetable substances. This apparatus may consist merely of
bristle-like appendages, or it may take the form of a pair of forceps
or little saws; and it appertains to the eighth segment of the
abdomen, or is a modification of the post-abdomen.

The young or larve are usually of a cylindrical form, and dis-
tinctly segmented. The head bears a pair of antenne, and one or
more pairs of ocelli or simple eyes. They are in most cases pro-
vided with a pair of jaws that move horizontally.

They are sometimes quite limbless, but usually there are three
pairs of walking legs, one pair attached to each of the three
segments that immediately follow the head, and which represent
the three thoracic segments of the perfect insect. Some of the
hindmost segments are often provided with other appendages called
prolegs, which not only assist the larve in their progression, but
also enable them to fix themselves firmly when at rest.

Larve are as a rule voracious feeders, and usually grow very
rapidly. The skin does not keep pace with the body in its growth,
and consequently soon becomes stretched. The larva then ceases
to eat for a time, and remains at rest, awaiting the moult or casting
of the skin. The skin soon splits behind the top of the head, and
after a series of contortions the larva relieves itself of its rent
garment. The new skin thus exposed is at first very soft and
affords a very imperfect protection to its owner; but it soon
hardens, and the creature returns to its food as vigorously as before.

Several such moultings take place before the larva is fully
grown, and then it prepares for its change to the pupa, and in
some cases for a longer or shorter period of quiescence.

Soine burrow into the ground, or seek out a sheltered crevice in
which to spend this stage. Many are provided with a spinning
apparatus, and either construct a silken cocoon, or, by means of
silk threads, bind together pieces of earth, wood, leaves, or other
substances to form a home, or tie themselves up in leaves which

P2

212 LIFE IN PONDS AND STREAMS

they have folded, or suspend themselves by means of bands or
threads of silk. )

The spinning apparatus consists of two tubular glands in the
abdominal segments, which secrete a tenacious fluid. These glands
open by a small aperture in the lip; and the fluid dries immediately
on exposure to air, thus forming an exceedingly thin fibre of silk.

After the larva has completed the preparations for its quiescent
period, it undergoes its last moult; and the insect then generally
presents quite a different appearance. The limbs of the perfect
insect are now distinctly outlined in the new skin, or even plainly
visible where the new covering is transparent, as is often the case ;
and the same is true of the antenne, proboscis, and other appen-
dages.

The skin now hardens, and the insect is a pupa, often with no
means of obtaining food, and usually no power of motion beyond
that of wriggling its hindmost segments.

The time spent in the pupal condition varies much in different
species. Sometimes it is only a few hours; but often the whole
winter, and in some cases even more than a year, is spent in this
inactive form. As a rule, however, aquatic insects spend the
winter as larve, and the pupal condition lasts for only a short time.

When the time arrives for the final metamorphosis, the pupal
skin bursts, and the perfect insect creeps out of its case, and sus-
pends itself by its legs till its wings are capable of supporting its
body in the air.

At first these appendages are moist and soft, and frequently
much below their normal size. They soon attain their full dimen-
sions, however, and shortly after become dry and rigid; and the
winged insect then takes to flight, seeks its mate, and engages
itself in the propagation of its species.

Such is a brief life-history of those insects whose metamorphoses
are complete; but it must be remembered that many exhibit
scarcely any change in form during their whole career. Some
there are that never develop wings at all, and others in the perfect
state differ from their larve or their pup but little except in the
possession of wings.

We have hinted at two features in which larve differ materially
from the perfect insects into which they develop—namely, that the
former are voracious feeders that grow with rapidity, while the
latter do not grow, but are to be regarded as the adults, gifted with
prodigious powers of reproducing their species. In accordance with

AQUATIC INSECTS 213

these facts we should naturally expect to find corresponding differ-
ences in structure. And such is really the case; for while in larve
we find the organs of digestion developed to an astonishing degree,
these organs are generally suppressed in the perfect insects, and the
organs of reproduction take a prominent place in the structure.

We have also referred to an extreme case in regard to certain
insects (Hphemeride) which require absolutely no food during the
short term of their adult existence; and also to others (such as the
Lepidoptera) which devour enormous quantities of solid food in the
larval form, but partake only of an inconsiderable amount of liquid
food in the adult stage.

There are, however, remarkable exceptions to this rule as far as
the food and the digestive organs are concerned ; for many insects,
among which a number of aquatic species take a prominent place,
are equally voracious in all their stages ; and these often exist for a
long period in the adult form, in some instances even for a longer
period than the larva. As an example we may mention the great
carnivorous water beetle (Dyticus marginalis), which often sees a
second summer after arriving at maturity.

As we proceed in the examination of aquatic species, we shall
observe many points in which these differ in structure from the
terrestrial and aérial forms. Thus we shall note that their build
is especially adapted to their aquatic habits, that their breathing
apparatus is modified in accordance with their mode of obtaining
air, and that the specific gravity of their bodies is also suited to
their requirements as floaters or bottom feeders, as the case may be.

In the first chapter were enumerated the different orders of
insects, and the chief characteristics by which they are dis-
tinguished briefly stated. We shall now examine the commonest
species to be met with in our ponds and streams, the list being far too
long to allow of even a bare mention of all of them; and we shall
deal with the groups in the order in which they have been pre-
viously named.

Tue RaYNCHOTA OR HEMIPTERA

In this order either the metamorphoses are incomplete or there
are none at all, and wings may be present or absent in the mature
insect. The larve are as a rule much like the imagines, but of
course always without wings, and the insects do not pass through
any quiescent stage corresponding with the pupe of the higher
orders.

214 LIFE IN PONDS AND STREAMS

All of them partake of liquid food only, and this is obtained by
suction from plants and animals; hence we find the mandibles and
maxille are not adapted for chew-
) TANG ’ ing, but modified so as to form part
my ‘N 4) pe of a suctorial beak. The labium is

ie (a)

produced into a long and sharply
‘ pointed tube, and within this work
bristle-like processes of the man-
dibles and maxilla, the whole form-
ing a very effective organ for piercing
and sucking. It is also interesting
to observe that neither the maxille
nor the labium is provided with
palpi.

The Rhynchota are divided into
two sections—the Heteroptera and
the Homoptera.

The Heteroptera include the

Fie. 190.—Movrn or a Bue bugs, some of which inhabit water,

a, antenne ; 7, labium: m, bristles of | While others derive their food from

the mandibles and maxille ; e, eye plants or are parasitic on terrestrial
animals.

The word Heteroptera signifies ‘ varied-winged’ (Gr. heteros,
another or different), and the section is so named because the basal
portion of the forewing is usually composed of a firm horny
material, while the other portion is thin and membranous. In some
species the wings are never fully developed, and in others only a
portion of the adult individuals have their wings perfected, the
remainder being entirely deprived of the means of aérial locomo-
tion. The pointed beak is not only an organ of suction, but is used
by several species as a means of defence. The bodies of most
of the Heteroptera are very flat, so that they can readily conceal
themselves in narrow crevices.

The Homoptera, or ‘ same-winged’ insects (Gr. homos, same),
are so called because both pairs, at least of those that have wings,
are membranous. The section includes plant lice, cuckoo spits, and
frog hoppers. They differ from most of the Heteroptera in that
their bodies are not flat, but very convex.

The Heteroptera, which we have more particularly to consider
here, are divided into two main sections—the Awrocorisa or Air
Buzs, also commonly known as Land Bugs; and the Hydrocorisa,

AQUATIC INSECTS 215

or Water Bugs. The former are mostly quite outside our province,
but they happen to include some insects which, although they
spend much of their time on the water, do not obtain air for
respiration from this element, but inhale it direct from the atmo-
sphere. The latter section contains some well-known aquatic
species.

We will first examine some of the aquatic Awrocorisa, popularly
known as Water Gnats and Pond Skaters ; but, before commencing
our descriptions of aquatic insects, it will be well to mention the
fact that the number of species which may from time to time
become entrapped within the net of an enthusiastic pond-hunter is
so great that we shall have to be content with accounts of repre-
sentatives only.

Water Gnats (Hydrodromica)

On the surface of almost every pond and sluggish stream during
the summer months, and even during the milder days of the winter,
we may see numbers of brownish insects, with very slender bodies
and long and exceedingly thin legs, walking on the surface of the
water; and others, of a somewhat similar build, darting about on the
surface with a series of leaps or jerks.

The former belong principally to the genus Hydrometra, or
Water Measurers, and are commonly known as Water Gnats, their
slender forms being very suggestive of wingless gnats.

As a rule we find them in little sheltered nooks at the margins
of ponds and streams, and also frequently making their way among
the herbage of the banks ; and their movements are so sluggish that
they are easily taken in the net or captured with the hand.

If we examine one of these creatures we are at first inclined to
compare it with a spider, for it appears to have eight legs. A closer
examination, however, shows that it has six legs only, and these
almost as fine as a hair; while the two foremost appendages are
the antenne, so disposed that they somewhat resemble a pair of
limbs.

The slender body is only as thick as an ordinary pin. It is
distinctly segmented, and covered with a hard chitinous substance,
but has only the rudiments of wings.

The thorax is elongated, and the three pairs of legs are attached
at the sides, and not beneath, as is usually the case with aquatic
insects.

216 LIFE IN PONDS AND STREAMS

The head is most peculiar. It is elongated to such an extent
that it is usually longer than the thorax, and nearly as long as the
abdomen. It is thickened behind, where it articulates with the
thorax, very thin throughout the greater part of its length, and
enlarged again at the front extremity,
where it gives rise to the antenne and
the beak. The eyes are small but
prominent, and are situated at the sides
of the middle and thinnest part of th
head.

The beak is long, but not so lorig as
the head, and is directed backward beneath
the latter. |

Locomotion is effected principally by
the middle pair of legs when the creature
is progressing on the surface of water, the
foremost pair being kept in readiness for
the seizure of its prey, while the hind legs
are usually directed well backward, so
that they serve the purpose of a rudder
as well as assist in the onward move-
ment.

Any one engaged in observing the move-
ments of Hydrometra for the first time
may well be astonished at the manner in
which the insect keeps itself entirely above

stagnorum the surface. The extreme lightness of the

creature may be in itself regarded as

sufficient explanation to those who are not acquainted with the
physical properties of the surface on which it treads.

It is a well-known law that a floating body rests on water in
such a position that it displaces its own weight of water. Thus a
piece of wood weighing one ounce will if thrown into a pond be
submerged to such an extent that it has pushed from beneath it
exactly one ounce of the liquid.

Sut if we closely watch Hydrometra as it rests on the water,
we find that no part of its body is beneath the surface —that even its
feet are dry. And yet we have some evidence to show that the
weight of the insect does tell a little, for under each foot is a slight
concavity ; and the surface, thus bent, has the effect of refracting

AQUATIC INSECTS 217

rays of light, and so producing small illuminated spots on the
bottom when the creature stands on shallow water. |

How is it, then, that the legs of Hydrometra, and, of course, of
other insects that walk or run on water, are capable of pressing
down the surface, and yet do not penetrate it ?

In order to answer this question we cannot do better than resort
to one or two very simple experiments.

Cover a piece of glass with a very light layer of oil or beeswax,
apply so little indeed that it is not even visible on the surface.
Now lay the glass on a table, and let a few drops of water fall on it.
On striking the glass the drops break up into little globes of water,
which run along like little balls for a short distance, and then
remain in the form of little spheroids, slightly flattened beneath by
their own weight.

Again, arrange a fine jet of water so that it may fall perpendicu-
larly into a pond or large aquarium, and you will see numerous little
globules of water, formed by the falling drops, rolling on the surface
just as a toy ball runs on a solid ground.

Now, why should the water remain in the form of globules on
the glass ; and why should the rolling drops on a pond refuse, at
least for a time, to unite with the water beneath it ?

The reason is this: the free surface of water is always covered
by a kind of invisible film, formed by the external molecules; and
this film cannot be broken without a certain amount of mechanical
force, but when once broken, the intruding substance passes through
the liquid easily. é

Where is the schoolboy who has not demonstrated the presence
of this ‘ surface film’ by gently lowering a needle on to the surface
of water, and thus causing it to float ?

The needle is made of a substance about eight times the weight
of its own volume of water, and yet it cannot break through the
film. But apply just sufficient pressure to push one end of the
needle through the film, and it sinks so rapidly that we can hardly
trace its path.

As a striking instance of the supporting power of the surface
film, make a small sieve with rather fine wire gauze, say about
three inches in diameter, and about one inch deep. Water thrown
into such a sieve will of course run out quite readily; and if an
attempt be made to float the sieve as a boat, water will as readily
run in and fill it, and in a moment the sieve is at the bottom.

But now dry the sieve, and then dip it into melted paraftin. It

218 LIFE IN PONDS AND STREAMS

comes out covered with a very thin and almost invisible layer of
this substance. Part of it, too, stretches across the meshes of
the gauze, thus closing the holes; but this may be removed at
once by tapping the sieve on the table or blowing one or two sharp
puffs of air at it while the paraffin is still hot.

Now pour water into the sieve, and you find that you can fill it
almost or quite to the top. Also put the empty sieve on water,
and the water below it refuses to enter, even though pressed by
the weight of the metal. So much resistance indeed does the
surface of the water now offer to the passage of the metal wire, that
a weight of two or three ounces may be placed in the sieve without
breaking the film.

This experiment proves beyond all doubt the presence of a kind
of invisible skin on the surface of water, and also shows that some
substances have less power of breaking through it than others. The
substances that most easily break through the film are those which
are most easily wetted by water, while those which are most effec-
tually resisted by it are those which come out dry after immersion.

Let the reader, when an opportunity occurs, catch a Hydrometra,
or any other insect that runs or jumps on water, and immerse it,
and he will notice that it emerges in a perfectly dry state. Nay
more, he may even find that the: creature has considerable difficulty
in breaking the surface film on its upward journey, notwithstanding
its remarkably low specific gravity, and consequent great tendency
to rise when under water.

This latter feature of the surface insects may also be demonstrated
by means of the little paraffined sieve. Thus, invert the sieve and
push it under water. Then put beneath it a cork sufficiently large
to make it rise. On reaching the surface, the film may be seen to
be heaved up above the normal level, but yet it refuses to break
and give passage to the metal, even though the upward force is con-
siderable.

I cannot refrain from mentioning one other property of the
surface film, again introducing it by means of a simple experi-
ment. Blow a soap bubble on the end of a piece of glass tubing,
and then leave the tube open. The bubble then gradually collapses,
driving the air back again. Or, as an alternative, bend up a piece
of wire into the form shown in fig. 192, and fix a piece of cotton
loosely across the circle. Now immerse the whole of the circle into
soap solution, and on withdrawing it a film of the solution will fill
the circle, and the thread will be found to move easily in the film

AQUATIC INSECTS 219

without breaking it. Next touch the film on one side of the thread
with a hot wire. It immediately breaks on this side, but the film
on the other side of the thread pulls the latter sufficiently to form
a strong curve.

These two simple experiments show that the film is decidedly
elastic—that it always exerts a considerable pull, which is spoken

Fic. 192._-Wire Rivne anv Cotrron Fic. 193.—Tuer THREAD PULLED
THREAD TO DEMONSTRATE THE BY THE ELASTICITY OF THE
ELASTICITY OF THE WATER Fitmu Fru

of as the tension of the film. It must be remembered, however,
that the film in these cases really consists of two films, with an
extremely thin layer of the solution between them.

An apology may seem necessary for digressing thus far on a
subject that may seem foreign to the purpose of this work; but I
have thought fit to do so because it is impossible to understand the
movements of many aquatic creatures, and these include others
than insects, without a knowledge of the properties of the surface film.

Now to return to the Hydrometra. In these creatures the meta-
morphoses are incomplete. The larve and pupe are both very much
like the perfect insects, but the former never have wings, and the
latter only possess these organs in a very rudimentary state. The
perfect insects, too, often have wings in an undeveloped form. Still
there is no difficulty in distinguishing between the perfect and the
earlier stages; for in the latter the larve, as is generally the case,
are covered with a soft and yielding skin, while the perfect insects
are always protected by a hardened horny integument. I have
already hinted at the necessity for this difference in the chapter

220 LIFE IN PONDS AND STREAMS

giving a general outline of insect life, where, it will be remembered,
- | spoke of the larva asa growing grub, undergoing several moultings
while the loose covering expands as the creature increases in size in
the intervals between. The perfect.insects, on the other hand, do
not grow, and therefore admit of the protection that can be afforded
by a chitinous coat of armour.

But, it may be asked, how is it that sects such as the Hydro-
metra, and many others, which eat ravenously in all their stages,
cease to grow as soon as the mature form has been attained ? The
reason is, and it applies to animal life generally, that the food taken
over and above that required to repair the waste to the system, and
which in the earlier stages adds to the size, is utilised in the mature
animals for the function of reproduction.

It may be mentioned that Hydrometra stagnorum is the only
British species of its genus; but there are a few other insects of
similar structure and habit.

Pond SKATERS (Gerrid@)

Allied to the Hydrometra are the Pond Skaters (genus Gerris),
which may be distinguished from the former, even at a considerable
distance, by their habit of sliding on the surface film of the water in

. . . ve ean -
Fic. 194.— Gerris gibbifera, Fie. 195.—Gerris argentata,
ENLARGED ENLARGED

a series of long jerks, and even sometimes of leaping from one
point to another. They are much more active than the Hydro-
metra, and instead of confining themselves to the sheltered nooks

AQUATIC INSECTS 221

close to the banks of ponds and streams, venture well out into
the open, and often allow themselves to be drifted along by the wind,
at which time their progress is naturally smooth and steady.

When alarmed, they some- ;
times dive below ; and it seems
probable that this is also done By ——_
at times in search of food,-for I
have seen one feeding on a larva
that was probably brought from
the bottom, for the larva was
one of the bottom feeders that = pyg. 196.— Tue Hew or Gerris
never come to the surface. argentata, SHOWING THE BEAK

Like the Hydrometra, the AND ANTENNA, ENLARGED
insects of this genus somewhat
resemble spiders, the antenne looking something like a fourth pair
of legs except at a close view. In fact they are even more like
spiders than their allies, for their bodies are not so slender. And
this is even more true of the larve, for at this stage the abdomen is
only slightly developed, and therefore the body is still wider in pro-
portion to its length.

The head is not long and slender as in Hydrometra, but the
eyes are prominent, and the antenne are
composed of four joints, the first of which is
much longer than the others.

The beak also is composed of four joints,
and contains four bristles by which the insect
pierces its prey. It is long, and is always
curved under the head; and the creature is
consequently compelled to hold its prey be-
neath its thorax while it sucks out the juices.
It will be seen from fig. 196 that the third
joint of the beak is much longer than the
others.

The structure of the thorax is peculiar.
The first pair of legs, which are used as pre-
hensile organs only, are placed at the front
of the first segment, and this segment is p,,. a Ae T
usually so long that the second pair of limbs, Ponp Sxarer, ENLARGED
which of course are attached to the second
segment, are widely separated from the first. So long in-
deed is the segment in question, that the second and _ third

222, LIFE IN PONDS AND STREAMS

pairs of limbs are often nearer to the tip of the abdomen than

the head.

The result of this peculiarity of the thorax is even more marked
in the larva, for at this stage the abdomen is so short that the
second and third pairs of legs appear to arise from the hindmost
portion of the body.

Nearly the whole surface of the body is clothed with a short
velvety hair which stands out at right angles to the integument ;
and this hair so effectually resists the water that the insect never
becomes wetted when immersed; and consequently, when it is
below the surface, the body is covered with a film of air, and looks
as if it were bright metallic silver.

When forcibly pushed below the surface of the water, the Gerris
is often unable to break through the film as it ascends; and, in its
struggles to find an exit, it will sometimes
turn over on its back, and walk in an inverted
position on the film, being kept in close con-
tact with the surface by its low specific gravity.
At such times an observation with the aid of
a hand lens will show that the water is
pushed up into a minute heap at the ex-
tremity of each of the limbs employed in this
mode of progression.

Fic. 198. — ForELEG The two front legs are normally bent
or Gerris argen- under the thorax, but these limbs are extended
tata, ENLARGED ie ae = :

when the Gerris is in the act of seizing its
prey.

The middle legs are thrown well out at the sides. These are
used for propulsion ; and being very long, they give the insect a
good leverage, enabling it to take strides of considerable length.

The hind legs project backwards. They are not used much for
propulsion, but serve the purpose of a steering apparatus.

Some only of the adults have their wings fully developed; in
others they are short, so much so that they have no power of flight.

The outer wings are strong, of a horny nature, and of a very dark
colour. The others are thin and membranous, and are folded.

The larve of Gerris may be found on ponds throughout the summer
months. They skate on the surface of the water, much like the adults,
but, unlike the latter, are often to be seen on submerged weeds.

The insects hibernate in the adult stage, but they do not seem
to be heavy sleepers, for they may be seen at large on mild days in

PLATE 111.

Danicisson & Co., London, del. ad. Nat. et Chremolith,

AQUATIC INSECTS 223

the middle of winter. They are not so active at this time as they
are in the summer, and may sometimes be seen at rest, with all
three pairs of legs folded under their bodies, so that they look just
like a little piece of floating stick.

The eggs are laid on pondweeds, to which they are attached by
a glutinous substance. j

The genus Gerris contains ten British species, all of which are
very similar in their general structure and habits.

WaTER Buas

We have now to deal with the Hydrocorisa or Water Bugs, which
may be readily distinguished from the Water Gnats both by their
form and their habits. Their bodies are usually of a stouter build,
or they are flattened like those of many plant bugs. The antennze
are not conspicuous, as in the case of Water Gnats, but are always
closely concealed in cavities below the eyes.

These insects also use their fore limbs as organs of prehension
rather than of locomotion, but, unlike those previously described,
have not the power of walking, skating, or jumping on the surface
of the water. They are bottom feeders, and spend their time almost
entirely in the mud or on the water weeds, coming to the surface
only for the purpose of obtaining air, or when about to migrate, or
to seek a hiding place in which to hibernate.

This section of the Heteroptera contains some well-known and
very interesting insects, a few typical examples of which we will
now examine.

WatTER BoatMEN (Notonectid@)
(Plate ITT, figs. 1 and 1a)

One of the first of aquatic insects to fall into the net of the
young pond-hunter is the common Water Boatman (Notonecta
glauca). In fact, so abundant is this creature that it is often a very
difficult matter indeed to find a pond, large or small, that does not
harbour it.

It is not a very easy matter to learn the life history and habits
of this insect while in its natural haunts; but fortunately it is easily
kept and reared in a moderately large aquarium, and its interesting
movements certainly make it a most desirable aquarium pet.

We have in this species a splendid example of adaptation to
aquatic life. The form of the body forcibly reminds one of that of
an inverted boat, for the back of the insect is bluntly keeled, and the

224 LIFE IN PONDS AND STREAMS

ventral surface flat ; and when we observe that the creature swims
in an inverted position (hence the term notonecta, which means
‘back-swimmer’), the likeness is seen to be still more perfect.
There is this difference, however, between
the shape of an ordinary boat and that of
the body of Notonecta—the former is
pointed in front, but not behind; while
the latter is blunt in front, and tapering
behind.

The head is moderately large and
protected by a very hard and smooth
integument ; and the large eyes are
Fic. 199.— Tur Water yendered very conspicuous by their dark

Boatman (Notonecta brown colour and brightly burnished

glauca)

surface.

The front segment of the thorax also is covered with a hard
and burnished integument; and there is no doubt that this feature
must materially compensate for the general bluntness of the fore
part of the body, by reducing the friction as the creature darts
through the water.

Behind this polished covering is a large black triangular plate,
with its apex directed backward. This is also a portion of the
covering of the thorax, and is named the scwtellum. The presence
of this plate is very characteristic of bugs generally, and it often
attains a very great size. In the present species it may be easily
mistaken for a portion of the elytra or outer horny wings, of which
we shall speak presently ; but there is
no risk of this confusion when the
wings are extended (fig. 200).

The wings of Notonecta are powerful,
and its flight rapid. . The outer pair
are partly horny and partly mem-
branous—a feature which has already

a ee ee been mentioned as characteristic of the

glauca, WITH WINGS Heteroptera.
EXTENDED A close examination will show that
each of these wings consists of three
distinct parts. The largest of these is an isosceles triangle, the
base of which forms the front margin when the wing is extended.
The usual colour of this triangle is a dark brown, with a long tri-
angular yellow patch near the body, and another light but less

AQUATIC INSECTS - 225

defined patch at the other extremity. The inner side of this tri-

angle forms the base for a second of similar shape but much smaller,
which is almost covered by a yellowish patch much like that on
the first. It must be remembered, however, that the colour of this
insect is very variable, the dark tints of the outer wings being often
almost entirely wanting.

These two parts together form the horny portion of the wing ;
and the third, which is attached to the other side of the largest
triangle, and forms the hindmost part of the tip of the wing, is
the membranous portion.

The outer wings somewhat resemble those of beetles, being
organs of protection rather than of flight; and, like these, they are
commonly spoken of as the elytra.

The inner wings are beautiful objects, not at all like what we
should expect to see in the case of a creature known by the detest-
able name of ‘bug.’ They are extremely delicate, and would be
almost invisible were it not for the dark but exceedingly fine
nervures which support the fragile membrane and the beautiful
iridescence exhibited by them when they reflect light at certain:
angles.

As regards the legs, it will be seen that the first pair are short,
and usually kept folded beneath the thorax. They are not used as
organs of locomotion at all, but serve to hold the creature’s prey,
and to anchor its body to weeds and to objects which lie on the bed
of the pond. This latter use is a highly important one, for the
specific gravity of Notonecta is very low, and it therefore requires
a strong limb to keep it below the surface for a great length of
time.
The second pair of legs are much longer, and are employed both
when the insect is pushing its way among the foliage and stems of
aquatic plants, and when it wishes to anchor itself to submerged
objects to rest.

The hindmost limbs are the longest of all, and are unmistakably
the organs of locomotion. They are long and strong, and moved
by powerful muscles. The last segment is fringed with a row of
stiff bristles, and thus the limb forms an admirable swimmirig
organ., In fact, we have here the one feature above all others which
justifies the popular name of ‘ boatman’ as applied to this insect.

No one who has ever seen Notonecta in motion in its native
element could fail to see its resemblance to a boat. The long hind
legs are stretched out at right angles to the body, and the latter is

Q

226 LIFE IN PONDS AND STREAMS

urged forward with considerable speed by their oarlike motion.
There are these differences, however, between the motion of the
oar and that of Notonecta’s third leg: The oar is rigid, and is lifted
out of the water during each back strake; but the leg of the insect
is gracefully bent while performing the back stroke, so that it offers
less resistance to the progress of the owner; and it always remains
submerged while the animal swims. Then, again, the experienced
oarsman reduces the resistance by turning the edge of the blade of
the oar to the water at the end of each stroke, just while it is being
raised out of the water; but the same end is gained in the case of
our Water. Boatman, not only by the bending of the limb already
referred to, but also by the depression of the bristles which form the
blade, for these bristles can be made to stand out or lie close, at the
will of the insect.

The limbs of Notonecta, at least the front and hind pairs, serve
other purposes than those already mentioned. Take the creature
out of the water, and lift up its elytra by means of a blunt pin. It
will resent this liberty of yours by endeavouring to keep the wings
tightly closed; and, as soon as you have ceased your endeavours,
both the hind legs will be used in vigorously replacing the wings,
as well as in a final brushing after they are set in their proper
position. The forelegs, too, are often employed in brushing over
the hard and polished integument of the front parts of the body.

The positions taken up by Notonecta when at rest are highly
characteristic. If anchored to a submerged object by means of its
forelegs, the hind legs are fully extended in such a manner as to
suggest a boatman resting on his oars; but sometimes a paddling
movement is maintained the whole time, as if the creature were
keeping itself in practice for a sudden dart in the event of the
approach of a suitable victim to satisfy its hunger.

As soon as it releases its hold we observe its tendency to rise,
owing to the low specific gravity of its body. So light indeed is
the insect that vigorous efforts are necessary in order to keep itself
near the bottom when not anchored.

We observe, further, that during a cessation of these efforts the
insect naturally turns over on its back. This of course is due to
the fact that the ventral portion of the body is the lightest. Hence,
if the creature allows itself to rise in the water without effort, the
ventral surface is the first to touch the surface film of the water.
As a matter of fact, however, the oars are always held in such a
position when the insect rises that they strike the surface film

AQUATIC INSECTS 227

before the body. Then, since these limbs are not able to penetrate
the film, they tend to keep the body entirely below it. But, the
abdomen being lighter than the head and thorax, the body swings
into an oblique position, so that it rests in equilibrium on three
points, all of which are being pressed against the surface film by the
buoyancy of the insect.

While the insect is in this position we have an opportunity of
examining its under surface, and of learning something of its
breathing apparatus; but we must not approach too suddenly, or
the creature, ever on the alert, will at once dart to the bottom. The
under side of the abdomen is now seen to be completely covered
with a film of air, which gives an appearance resembling that of
polished silver, and is particularly striking when the insect is
swimming in bright sunshine. We shall see too that the hairs at
the tip of the abdomen project a little above the surface of the
water, and that the air entangled between them forms a means of
communication between the atmosphere and the layer of air that
covers the ventral surface of the body.

Now let us take our Notonecta out of the water by making a
sudden sweep at it with a small net. Its body is perfectly dry.
Indeed the water never touches the lower surface, being kept off by
the film of air that remains in contact with it. If we examine the
creature we find that this surface is covered with short hairs, the
chief of which are arranged in rows on either side; and it is these
which entangle the film of air that prevents contact with the water.
Further, a lens will reveal the abdominal stigmata in the depres-
sions between these rows of hairs, and if we return the insect to its
native element we may even watch the manner in which the air is
made to pass over the breathing holes.

It will be seen that the rows of hairs on each side of the stig-
mata not only serve to entangle air, and thus form a film that
communicates freely with the atmosphere above, but they also form
clear passages, along which air can pass freely over the openings of
the trachee. The movements of the air may also be observed under
the edges of the elytra, which are sufficiently transparent to allow
them to be seen.

The air passes from the tip of the abdomen, along the channels
at the sides where the stigmata are situated beneath the edges of
the elytra, till it reaches the thorax, also provided with stigmata.
Then, having given up some of its oxygen to the tracheal system,
and become more or less charged with carbonie acid gas from that

2

228 LIFE IN PONDS AND STREAMS

system, it escapes in the form of occasional bubbles from beneath
the bases of the wings.

If we disturb Notonecta while enjoying the benefits of this free
communication with the atmosphere, we find that it is unusually
buoyant, and consequently has to struggle hard to reach the bottom.
This is due to the large amount of air stored beneath the elytra.
During its struggles, however, we often observe that a very large
bubble becomes disengaged from beneath the shoulders. Also, when
the insect has anchored itself, a bubble may still be seen to form
at this part, and to grow gradually larger, till at last it breaks free.

Notonecta is entirely dependent on air obtained at the surface
of the water, not having any means of absorbing dissolved oxygen.
Hence the creature is obliged to make frequent visits to the surface
for the purpose of renewing its supplies. In the summer, however,
it will often remain at the surface for a long time together, thus
apparently enjoying the sun’s rays as well as the uninterrupted
communication with the pure air.

At times, too, it will turn with its back uppermost, and support
itself on weeds in such a manner that it is half out of the water.
It may often be found in such a position when the sun is high and
bright, thus showing its undoubted appreciation of the light and
warmth of summer. At such times the elytra are often raised a
little, as if the insect were about to fly ; but this is probably only a
means of putting the stigmata in direct communication with the
free air.

I have spoken of the movements of Notonecta in the water,
but how does it behave when out of its natural home? Put the
creature on the ground, and how awkward is its motion! Its
front and middle legs are practically useless. True it can help to
drag its:body along by means of the latter, but walking is out
of the question. The oars are no longer gracefully wielded and
feathered, but are jerked so violently that the body is thrown about
in a most irregular manner.

But the creature is not always so awkward when out of the
water, as every one will admit who has seen it fly. Its flight is
rapid and steady, and accompanied by a humming sound; and is
usually taken in the evening, though at times it flies in very bright
sunshine.

It sometimes takes its flight direct from the water, for, unlike
many of the aquatic beetles, it does not necessarily require a foot-
hold while expanding its wings. It will leap out of the water by a

AQUATIC INSECTS 229

strong stroke of its oars, and then suddenly expand its wings before
it has had time to fall back. I find, however, that this is not the
usual mode of procedure in captivity.

Put a number.of the insects into a pan or tub of water. Leave
them undisturbed after sunset, but have sufficient artificial light to
enable you to watch their movements. You will soon see them
climbing up the sides of the vessel which holds them, even if the
sides are perpendicular and as smooth as glass. But how can they
climb on such surfaces as these, seeing that the legs are not supplied
with suckers? Here again the creature makes use of the properties
of the surface film of water. In its struggles to leave the water it
wets the side of the vessel. The little drops of water then cause its
body to adhere, and with its oars pushing against the wet glass,
and aided by the tenacity of the films, gradually, and often some-
what laboriously, it finds its way to the edge. Here it obtains a
steady foothold, expands its wings, and starts on its flight.

Notonecta is entirely predaceous. It will fearlessly attack an
animal larger than itself, hold it firmly under its thorax by means
of the forelegs, and then suck its juices till there is little or nothing
left but a mere skeleton. If disturbed while feeding, it will swim
about with its prey as though its food were dearer than life itself.

Those who have handled Water Boatmen freely probably know
something of the power of the beak, for the insect does not hesitate
to use this organ either as a weapon of offence or defence. The
pain produced by the intrusion of the bristles is so sharp that it is
difficult to believe that it is caused solely by mechanical irritation—
that no irritant poison has been injected into the wound. But the
sensation is of very short duration, and there are no signs remain-
ing which would suggest the presence of any poisonous substance.

From what has just been said it will be seen that the ‘ bite’ of
Notonecta is not really a bite, not being produced by the approach
of two opposing jaws; nor does it resemble the stinging of hymeno-
pterous insects, for in this case a powerful poison is injected into
the wound.

The eggs of Notonecta are laid singly on the stems of pond-
weeds or .on decaying fragments of aquatic vegetation, each egg
being deposited in an incision made by means of a_protrusile
ovipositor.

The larve are much like the per‘ect insects, but of course have
no wings. In the pupe the wings are rudimentary.

In all three stages the creatures are equally predaceous, and the

230 LIFE IN PONDS AND STREAMS

perfect insect, like many rapacious species, enjoys a rather long
existence. In the indoor aquarium it may be kept alive through-
out the winter, and, unless the apartment in which it is situated
is a very cold one, it remains active the whole time.

Several other insects are often included under the popular title
of ‘ Boatmen,’ but they differ from Notonecta, which is the only
member of its genus, in not having their backs distinctly keeled. In
fact they are mostly very flat on the upper side, and their chief
right to the title lies in the mode of using their oarlike legs; and
even here the resemblance to the true ‘boatman’ is not nearly so
marked as in the case of the species just described.

THE CoRIXIDE

If we take up a position close beside a pond and watch the water
intently we are almost sure to see a number of little insects of a
dark colour, making a very sudden appearance at the surface from
below, and, after a momentary pause, darting away again with
great speed to the bottom.

We try to secure one with the net as it makes its appearance,
but its visit is of such short duration, and its movements so rapid,
that we do not succeed. Then the thought strikes us that a dash
at the bottom may enable us to take it by surprise as it rests. We
try it, and with what result ? Among the contents of the net we
find a number of small insects jumping about by means of long legs
that remind us of the oars of Notonecta, and which are evidently
not adapted for motion on land.

The insects to which we refer are much smaller than Notonecta,
but the resemblance is at first sight so striking that the casual
observer might suppose them to be the young larve of that species.
But no; they are provided with perfectly formed wings, and must
therefore be regarded as the perfect forms of a smaller species.
They belong to the family Corixide, of which nearly thirty species
form the typical genus Corixa.

When we examine one of the Corix@ we find certain points of
resemblance between it and Notonecta. Its body is somewhat
boat-shaped, but instead of being keeled is almost flat on the back.
The beak resembles that of the true ‘boatmen,’ but is considerably
shorter in proportion; and the scutellum, though present, is not
conspicuous, but is covered by an extension of the first thoracic
segment.

AQUATIC INSECTS 251

The front legs are not so well adapted for prehension. The
tarsus consists of a single long joint, and this is fringed with stiff
hairs, so that it becomes useful in helping the insect to swim. The
middle legs, which are the longest, are slender, and the tarsus ter-
minates in two long and thin claws. The hind legs, as in Notonecta,
are long and strong, and are used after the manner of oars; and the
_tarsus, which in this case consists of two joints, is flattened, and
fringed with bristles.

The outer wings are horny with the exception of the tips; and
the inner ones, which are membranous, exhibit a beautiful irides-
cence.

Now let us examine a Corira in its native element, introducing
with it, for the sake of comparison, a Notonecta. We put them

Fic. 201.—Coriza Geoffroyi, Fic. 202.—Corixa Geoffroyi,
ENLARGED UNDER SIDE, ENLARGED

into a bottle of clear water, at first without any weed or any other
solid object. They both dart about vigorously, and, not being able
to distinguish between the colourless glass and the water, dash
their hard heads against the former with a force that would be fatal
in many other creatures.

At last these efforts to secure a shady corner become less furious,
and both the insects resolve on resting. But how different are
their modes of swimming, and also their positions of rest !

Notonecta swims on its back, as we have already observed, but
the Corixa keeps its back uppermost all the time. The former also
rests in this same position; and having no object below to which
it can anchor itself, has to be satisfied with a position just below
the surface, its light body being kept there by the film. But some

232 LIFE IN PONDS AND STREAMS

species of Corira are heavier than their own volume of water, and
can remain at the bottom without anchorage.

Having observed these differences, we introduce a little gravel
and some aquatic vegetation, and then prepare for further observa-
tion. Both creatures are soon anchored below, the Corixa almost
invariably choosing the very bottom, often indeed hiding itself quite
out of sight if possible, but Notonecta seeming equally at home at
the bottom or in midwater.

Again, we notice that the two insects breathe in very different
ways. The Corvxa does not float to the top without effort, on
account of the higher specific gravity of its body; but when it
swims to the surface, its body remains stationary for a time with
the back uppermost, this part being lighter than the ventral portion,
and especially the thoracic region, which contains the stigmata. A
film of air extends from these, round the very narrow neck, to the
surface of the water, thus forming a communication between the
stigmata and the pure atmosphere above. In a moment this air is
exchanged for a fresh supply by diffusion, aided by a downward
bend of the head, and the creature darts below with this supply
between its head and thorax.

Like Notonecta, the Corixe generally fly by night, and are
attracted by bright lights. They hibernate during the cold
weather, burying themselves in mud, or congregating under dead
leaves at the bottom of the water; but they resume activity in
mild weather, even in the depths of winter, and if kept indoors
retain their activity throughout the season, devouring each other
if no other food is provided for them.

The eggs are fastened by a glutinous substance to submerged
objects, and the larve resemble the perfect insects except in the
possession of wings.

The species figured (Corixa Geoffroyt) is both the largest and
the commonest of the typical genus, and may be found in almost
every weedy pond. Its colour is a dark brown, but tinted with
yellow, the latter tint being due to transverse rows of small
yellowish spots on the thorax, as well as to minute yellow hairs
scattered irregularly over the elytra. The head is yellow, and the
eves large and black.

These latter characteristics obtain more or less in all the Corize;
but some species of the same family have no yellow markings on
the thorax, and in others the scutellum is not hidden by the proto-
thorax.

AQUATIC INSECTS 233

It may be mentioned in conclusion that the members of this
family are so similar in general appearance that it is a difficult
matter to distinguish between species; but the mature small species
may be readily distinguished from the larve of the larger ones by
the presence of the wings.

WATER SCORPIONS

These insects are so called because of the peculiar form and
action of the front legs, which are used entirely as prehensile organs,
and disposed in such a manner as to remind one of the forceps of
the scorpions of warmer countries. It must not be assumed, how-
ever, that these two creatures—the water scorpion and the true
scorpion—are closely related because they are similarly named.
The latter is not an insect, but belongs to the same class as spiders
and mites, and possesses eight legs; but the former is an insect,
with only six legs.

The Water Scorpion (Plate III, figs. 2 and 2a) is one of those
insects that are sure to be found in the net of a pond-hunter, unless
indeed all his energies are eonfined to one of those few localities
where the commonest and most widely distributed species fail
to make their appearance. And once found it is certain to be re-
cognised, for it is the only member of its genus, and there is no
other British species for which it can possibly be mistaken.

If any insect forms can rightly be described as ugly, then surely
the Water Scorpion (Nepa cinerea) must be included under that
category, for neither its flat buglike shape nor its dirty mud-brown
colour is particularly pleasing to the eye. Yet the creature is cer-
tainly a very interesting one, and though not likely to prove attrac-
tive at first sight, it has its good points, and may even be made to
display a little bright colouring when we have learnt where to look
for it.

Its body is broad, flat, and thin, and shaped much like a small
leaf ; hence it is not always readily recognised in the pond or among
the contents of the collector’s net. If it rests on aquatic weeds, as
it often does, it is easily mistaken for a dead leaf; or if on a muddy
bottom, it is hardly to be distinguished from the mud itself, so
closely does it resemble the latter in colour. In this position, too,
we often find its back covered with a deposit of pond sediment that
adds to the difficulty of detection; and this difficulty is still further
increased by the general sluggishness of the creature,

23 LIFE IN PONDS AND STREAMS

So sluggish indeed is the Water Scorpion that it would die of
starvation were it not for the agility of the movements of its front
prehensile legs. Its resemblance to a dead leaf and the similarity
of its colour to that of the mud in which it grovels are of little service
as a protection against enemies, for, judging from observations
of varied collections of predaceous insects in aquaria, the Water
Scorpion is not regarded as a delicate morsel. It is not often
attacked by its carnivorous companions, who prefer rather to devour
their own species. And this seems wise on their part, for there
cannot be much nourishing matter between the two layers of the
integument of the flat Nepa.

The resemblances referred to, however, are a great help to the
insect, for they enable it to lie in wait for its unwary victims without
being detected. Thus when on the watch for prey the Water Scorpion
remains motionless, being apparently aware of the deficiency of its
locomotive powers, and trusting to its deceptive appearance and the
alacrity of its front legs. When, however, a hapless victim comes
within range the two forcep-like legs close upon it smartly, allowing
no hope of escape; while at the same moment the short but
sharp beak is thrust into the victim, and the process of suction
commenced.

Let us now note a few points in the structure of Nepa. The
forelegs are very peculiar. They are furnished with sharp claws,

Fic. 204.—Foretec or Nepa,

Fic. 203.—Nepa cinerea WITH ENLARGED ; SHOWING THE DEEP
FoRELEGS FOLDED GROOVE WHICH RECEIVES THE
TARSUS

bent inwards; and are so constructed that they can be closely folded
after the manner of a pocket knife, one part being deeply grooved
in order to receive the other. The other legs are rather slender, and
are used for walking only.

AQUATIC INSECTS 235

The outer wings are horny, with a membranous portion at the
tips. They overlap slightly when closed, but the scutellum always
remains visible. The under wings are membranous, and rather
opaque. They are of a smoky grey-brown colour, with a longitudi-
nal scarlet streak extending from the base to the middle.

It is when the wings are extended that we see the beauty of this
insect, for the upper surface of the abdomen is rather richly coloured
at the edges with bright red, and this
forms a pleasing contrast with the wide
patch of black down the middle.

The eyes are small, but rendered con-
spicuous by their intense blackness; and
the antenne are concealed in grooves be-
neath them.

At the tip of the abdomen is a long
and slender filament that closely resembles
the ovipositor of some other insects, but
it is really a breathing tube, and is in py, 205.—Nepa cinerea
communication with the trachee. It is wrrn Wriycs EXTENDED
composed of two distinct parts, which may _
be easily separated by means of a needle. Each half is grooved on
the inner side, so that they form a tube when brought together.
They are locked together by rows of bristles on the inner edges,

If we watch the insect when it is crawling over pondweeds we
often see it-walking backwards, with the tail filament directed up-
wards, until the latter is thrust through the surface film of the
water ; and in this way it opens up a free communication between
the trachee and the atmosphere.

The tracheal system consists of two main tubes which run longi-
tudinally along the sides of the body, giving off numerous branches
at right angles. These two main tubes terminate in a pair of stig-
mata at the tip of the abdomen, just at the base of the breathing
tube, and are thus brought into communication with the free air.

Nepa appears to require very little air, especially during the cold
weather, when it exists in a semi-dormant condition. For hours
together it will remain in midwater, attached to pondweeds, with-
out ever approaching the surface. And even during the summer
months—the period of its greatest activity, if we may truthfully
apply such a word to so sluggish an insect—it will often remain
below for a long time together; and yet on the other hand it will
often take up a position close to the surface, and stay there for a

236 LIFE IN PONDS AND STREAMS

long time with the tip of its breathing tube just exposed to the
air.

During the prolonged intervals spent below, I have reason to
believe, the insect is not always deprived of fresh air. I have often
seen it walking backwards on weeds, with the tail filament directed
obliquely upwards, just as though it were feeling for the surface.
Now it has often happened on such occasions that the growing
weeds, exposed to a good light, supported a number of small bubbles
of gas, consisting principally of oxygen; and as soon as the tip of
the breathing tube penetrated one of these bubbles the insect ceased
to move, being apparently satisfied at finding a temporary supply.

This same feature may be observed more readily if larger bubbles,
produced by forcing a fine jet of water into the aquarium, become
entangled in the dense filamentous foliage of such a plant as the
Hornwort. In this way a number of moderately large bubbles may
be easily suspended in the water, and the Nepa will soon pierce one
as it moves about.

A restless Water Scorpion may be even more easily quieted by
entangling a large bubble of air in a small mass of cotton wool which
has been lightly oiled, and then presenting it to the extremity of the
breathing tube by means of a thin piece of stick.

Water Scorpions hibernate in the perfect state, as has already
been hinted. In an indoor aquarium they remain more or less
active throughout the winter, except when exposed to extreme
cold. Those I have at the present time (middle of January) are
kept in a room in which a fire is seldom made; and they remain
motionless, as long as they are undisturbed, huddled together in two
or three small clusters on the American Pondweed.

The eggs are very curious objects. Each
one is oval, with seven little hairlike projec-
tions, arranged in a circle and forming a small
conical cup. They are laid in a continuous
string, each egg lying in the cup formed by the
filaments of the preceding one. After they
are deposited the seven filaments curve back-
Fic. 206.—Larva or Ward, forming as many little hooks.

Nepa cinerea The larva of Nepa is very similar to the

perfect insect; but its body, though smaller,
is not so thin and flat. Two little swellings at the side of
the thorax mark the position of the rudimentary wings. It is
further distinguished by the absence of the slender breathing tube,

a

AQUATIC INSECTS 237

instead of which it has a thick, short, and bluntly pointed projec-
tion at the tip of the abdomen.
The insect is aquatic throughout the whole of its existence.

Ranatra linearis

There is another insect that is popularly known by the name of
Water Scorpion; but, as will be seen by its name just given, it
belongs toanother genus. Like Nepa cinerea, it is the only British
member of its genus. ;

Fic. 207.—Ranatra linearis

At first sight it seems to form a marked contrast to the last
species, for its body is very long and slender; and instead of being
flat, as is generally the case with bugs, is cylindrical. The colour is
also much darker, being of a very deep ashy brown, almost black
in fact.

The head is small, and the eyes, though small, are prominent
and conspicuous. The beak is shortand sharp. It is curved down-
wards when not in use, but directed forward when the insect is
preparing to attack.

This insect is hardly to be described as active, but is certainly
more so than Nepa; for not only does it display considerable agility
when in pursuit of its prey, but will also boldly defend itself when
in danger. It will fearlessly attack any creature that affronts it,
and will close its pincerlike forelegs on any object thrust in its
path.

The forelegs are very long and slender, and are used solely as
prehensile organs. The basal joint, which is usually very short in
insects, is in this case much elongated. The femur also is very
long. It is also curved, and bears a toothlike projection beyond the
middle. The portion beyond the tooth is grooved like the femur of

238 LIFE IN PONDS AND STREAMS

Nepa, in order that it may receive the tibia and tarsus when these are
not required for raptorial or defensive purposes. It will be seen, too,
that the tibia and the tarsus together form a sickle-shaped and
sharply pointed portion, admirably adapted for its deadly purpose.

One would hardly imagine that an insect with such a slender
sticklike body could possess two pairs of wings; yet such is the case.
The outer pair are of a horny nature, excepting a small membran-
ous portion at the tips; and they are so narrow that they meet in the
middle of the abdomen without any overlapping except in the narrow
membranous portions. The hind wings are wider, and form the
real organs of flight. They are exceedingly delicate and transparent,
and are neatly folded beneath the outer pair when not in use.

Like the last species, Ranatra delights in grovelling in mud
and in clambering on pondweeds, now and then coming near the
surface and thrusting its long breathing filament into the air.

When taken in a pond net, it is often so sluggish in its move-
ments that it may be easily mistaken for a piece of stick, and it
frequently makes little or no endeavour to free itself from the mud
and weed that have been dredged in with it. When, however, it
attempts to walk, it covers ground much more rapidly than its
brother scorpion, and it often elevates its body to such,an extent
on its long and slender legs as to suggest the idea of a creature
on stilts. The position of the forelegs, too, is very characteristic.
They are elevated above the body in such a manner as to add to the
menacing attitude of the insect.

Its mode of walking is also peculiar, for it moves its second
legs. forward, one after the other, while the hind legs remain
stationary, and then pulls up both hind legs while the others retain
hold. Thus it progresses by means of a series of long strides, using
each pair of walking legs almost as one.

Ranatra is easily kept alive in the aquarium, providing it is
supplied with food; and, as to this, it is not particularly dainty. It
will attack small fishes, worms, freshwater shrimps, and almost
any kind of insect larva. It lies in wait on the mud or, more
generally, among weeds, with its raptorial forelegs in position for
the attack; and so nimble are the movements of these seizing
organs that it often succeeds in securing creatures that move
rapidly in the water.

Occasionally it will take to flight ; and when it alights upon the
water, or when placed on the water after having been removed, it
has some little difficulty in getting below, on account of its extreme

AQUATIC INSECTS 239

lightness, and partly on account of the fact that its body does not
become wetted. As it thrusts itself into the water the surface film
is forced down all around it, so that, for the time, it lies in a little
hollow.

The eggs of Ranatra are laid singly on submerged objects
Each egg has two hairlike filaments, but these do not clasp the
succeeding one as in the case of Nepa.

The larva is similar to the adult in general form, but it has no
long breathing tube, and of course no wings.

Ranatra is not an uncommon insect, but it is not nearly so
plentiful as Nepa.

Naucoris

We shall briefly note one other Water Bug—a species called
Naucoris cimicoides, which is sometimes included in the same
family as Nepa and Ranatra, but sometimes placed in a separate
group.

Its body is oval, slightly pointed at the tip, and broad and
depressed, but not nearly so flat as Nepa. The upper surface is
convex, and completely covered by the outer
wings, with the exception of a very narrow
margin on each side.

This insect is not so widely distributed as
the other Water Bugs we have mentioned, but is
extremely common in some parts. In many yy, 208. — Nau-
ponds indeed it actually swarms, and several coris cimicoides
specimens may be taken at almost every dip.

Its habits are like those of Notonecta in some respects. It swims
by means of its long and fringed hind legs, using them after
the manner of oars, and proceeding with a vigorous but jerky
motion.

It spends most of its time at or near the bottom, where it
anchors itself by its front legs to the pondweeds ; but it comes to
the surface at frequent intervals to renew its air supply, and this
respiratory movement is carried out much in the same way as in
Notonecta. -

The middle legs of Naucoris are rather long, but very slender,
and of little use for swimming. ‘The forelegs are very short, and
used for prehension only. They are provided with long and sharp
claws, and are exceedingly powerful in comparison with their size,
the femur being of a globular form, thus accommodating the well-

240 LIFE IN PONDS AND STREAMS

developed muscles which enable the creature to seize and hold its
prey. |

Like Notonecta glauca, Naucoris flies well, but usually employs
this means of locomotion during the hours of evening twilight alone.
If kept in an indoor aquarium it will frequently fly freely about
the apartment in which it is kept, and, like moths, is attracted by
artificial lights.

Its outer wings are stiff, and serve more for protection than for
flying ; but the hind wings are exceedingly delicate in structure, and
exhibit a most beautiful display of iridescent colouring.

Fic. 209.—Naucoris Fic. 210.—HEAD oF
wiItH WINGS EX- Naucoris, SHOWING
TENDED THE BEAK, - EN-

LARGED

The beak is exceedingly sharp, and is directed backward between
the bases of the forelegs. The latter are usually directed forwards,
but in our engraving the left one is turned out of its natural position
in order to show the whole of the beak, which would otherwise
have been hidden from view. The pain produced when the beak
pierces one’s skin is intense, but it lasts for a very short time.

AQUATIC SPRINGTAILS

We have next to deal with some very small insects belonging to
the order Thysanura. Most of the species are terrestrial, and live
under the cover of stones, leaves, and other objects in dark and
damp places, and hop about by means of filaments which are bent
under the abdomen. ‘This latter feature has earned for them the
popular name of Springtails.

There are a few aquatic species, the commonest of which—the
Common Water Springtail (Podwra aquatica)—may be taken as a
type of the group.

If we examine the surface of water in ditches and at the margins
of ponds we may often meet with black patches that look like

AQUATIC INSECTS 241

collections of floating dust. Thrust the end of a stick into one of
these clusters, and immediately the particles disperse. Remove the
stick and watch steadily, and they are seen to collect again.

These movements are mysterious when viewed at a distance of a
few feet ; but when we look more closely we find that each of the
black particles is really a little animal that leaps about actively on
the surface film.

It is not an easy matter as a rule to watch the movements of
these creatures in the field; but they do well in an aquarium, and
it will repay one to secure a number of them for observation at
home.

They may be easily taken in this manner: Gently push a
wide-mouthed bottle into the water close beside a cluster of the
creatures, holding it a little obliquely with the mouth uppermosi.
As soon as the lower part of the rim of the bottle passes below the
surface, the surface water will flow into the vessel, carrying the
floating insects along with it.

This is the most convenient method of securing them when they
are required isolated from other forms of pond life. A preferable
plan, in my opinion, is to make a dash at cluster after cluster with
a small pond-net, and then transfer the contents of the net, weeds
and all, to a small bait-can.

When you return, throw all into a moderately large vessel of
water—a glass aquarium or an earthenware pan—and you will soon
see the little creatures, rather less than a line in length, collecting
on the surface of the water. Some also will attach themselves tc
the sides of the vessel.

Whenever they are disturbed, either by tapping the vessel,
touching the water, suddenly throwing a strong light on them, or
by any other means, the scene becomes a very lively one. The
clusters break up, and those round the sides skip about, jumping
from the water to the sides of the vessel, and then back again to the
water, but soon becoming steady again when the disturbance is
over.

But even then they are by no means motionless, for, though the
clusters do.not change much in appearance, the little insects are
almost continuously on the move.

We now remove one of them for examination under a magnifier.
A camel-hair brush is moistened slightly between the lips and then
pressed gently on the animal’s back. It will adhere slightly, and
may be quickly transferred to a small cell on a glass slip and

R

242 LIFE IN PONDS AND STREAMS

covered with a cover glass. This must be done quickly. or the
Podura will soon recover its feet, and then leap off the brush
with a powerful movement of the bristles which form the ‘ spring-
tail.’

Having captured the insect in this way, we study it with a
powerful hand magnifier, or, better still, by means of the low
power of a compound microscope.

Now we see that it is really an insect, for it has six pairs of legs.
The segments of the body are also very distinct, but there is no
constriction dividing the thorax from the abdomen. In fact the
body is thick and clumsy, cylindrical in form, but tapering slightly
towards the tip of the abdomen.

The body appears quite black in a moderate light, but when
more strongly illuminated it is seen to be of a bluish colour. It is
so opaque, too, that it is of no use reflecting
light from below it; but it is best viewed
when a strong light is thrown down on it by
means of a condensing lens.

The antenne, like the body itself, are
thick and clumsy. The legs are reddish, and
short and thick. They are provided with stiff
hairs, and terminate in a single sharp claw.
The mouth is not suctorial, like that of the
Hemiptera, but is provided with jaws for
chewing solid food.

Podura has no wings in the adult state,
and undergoes no metamorphoses ; hence the
Vis. 814s. Pagans adult is to be distinguished from the earlier

aquatica, ENLARGED stages only by its size.
DIAMETERS If captured before they are fully grown,
and then kept under observation in the
aquarium, specimens of a-much lighter colour than the others may
often be seen. These have just undergone a moult, and thus
appear in their new dress, which turns darker shortly afterwards.
Where a large number are kept we may also observe the cast skins
floating on the surface of the water.

It will be necessary to turn the Podwra on its side or its back in
order to see the springing apparatus. This consists of a prolonga-
tion of the abdomen in the form of a forked appendage bent under
the body. When the insect leaps, this appendage is forcibly ex-
tended, so that it strikes against the surface film of the water, or

AQUATIC INSECTS 243

against the solid object on which it happens to be stationed, thus
lifting the body into the air.

The length of the leap varies from one to three or four inches—
that is, from about twelve to fifty times the length of the body. It
seems surprising that the surface film should be capable of resist-
ing the sudden pressure necessary to lift the fat and bulky body
of Podura with such force and yet remain unbroken. Yet such
is the case.

When the insect alights, too, the film resists the blow so effec-
tually that it is not broken, and the Podura is therefore never
wetted during the contact. And even if the film were to break and
the creature become more or less submerged, still it would not be
wetted, for the body is covered with short close hairs which prevent
the water from coming in contact with it ; and thus the submerged
Podura would be covered with a thin layer of air entangled between
the hairs.

Although the insect displays so much agility when leaping about,
yet it is probably at this time that it appears at its worst. It is
eminently superior to the cat in leaping powers, but it might learn
much from that animal as to how it should fall. The Podwra is as
likely to fall on its back as on its feet, and when it does so, it
scrambles about in a most awkward manner in order to gain its
footing. It is only fair to mention, however, that this awkwardness
is far more apparent when the insect has been removed from its
natural habitation—when placed, for example, on a sheet of paper.
On the other hand, Podura seems to be able to walk far better on
a solid substance than on the surface film of water. The latter,
though unbroken by its claws, seems to give way behind it when it
tries to thrust its body forward.

Podura is essentially a creature of the surface, but it evidently
descends into the water sometimes. It appears to have no power
to penetrate the surface film except by walking down the stems of
water weeds, or down the banks of the pond or ditch in which it
lives. In this way it can make use of its legs and claws to over-
come the resistance offered to its progress.

The Podura is so small that the young pond-hunter may have
no desire to preserve specimens for his collection. As a rule it
is to be readily obtained through the greater part of the year, and
therefore there is no need to set by specimens for examination.
Again, a colony of these insects, once deposited in an aquarium,will

R2

244 LIFE IN PONDS AND STREAMS

establish themselves and give rise to successive generations year
after year.

Should the reader, however, desire to preserve Podura, he must
cive up all idea of dry preservation, for the body of the insect soon
shrivels to a shapeless mass. I have found specimens keep well in
asmall tube of diluted alcohol ; but where the necessary knowledge
and skill are possessed, they should be preserved as microscopic
objects.

Aquatic NEUROPTERA

The Neuroptera is such a varied group of insects that it is im-
possible to name many features common to all; and this difficulty
is further increased by the great difference of opinion as to the
extent of the order. They all agree, however, in the characteristic
intended to be expressed by the word newroptera, which signifies
‘nerve-winged ;’ for in all of them the wings are divided into a
large number of spaces by a delicate network of nervures.

The wings are four in number, and both pairs are similar in
structure, consisting of a very thin and transparent membrane.
They are also nearly equal in length, and are seldom folded ; nor
do the foremost pair cover the others as in the winged species pre-
viously described.

The subdivisions of the order vary considerably in their meta-
morphoses. Some pass through a quiescent pupal stage, while
others are active and predaceous throughout their existence.

The aquatic insects of this order include Dragon Flies, May Flies,
and Stone Flies.

Dracon Furies (Odonata)

These insects, at least the commonest of them, are well known
to every lover of the country, for they are to be seen flying in the
neighbourhood of ponds and streams almost everywhere during the
summer months. But though so well known in the perfect state, it
is doubtful whether many of my readers are acquainted with their
whole life history and their habits at different stages of their exist-
ence. In fact there is yet much to be learnt concerning many of
the British species, which number nearly fifty, even by experienced
entomologists; for the rarer species, and even some of the more
common, are as yet imperfectly known in their larval and pupal
states.

Although there are marked differences in the form and colouring

Fic. 212.—Agvatic INsEcTs

1, Ephemera vulgata; 2, Ephemera larva; 3, Platetrum depressum; da, P. depressum
emerging from pupa case; 4, 7, depressum, larva; 5, Calopteryx virgo; 6, Agrion
minium;, 7, Phruganea grandis ; 8, Phruganea, larva cases

246 LIFE IN PONDS AND STREAMS

of the various species, yet, as far as their habits and life histories
are concerned, they may be divided into two groups, so that a general
description of a chosen type of each will answer equally well for
the others.

We will first note the chief characteristics of the perfect insects,
and then speak of the earlier stages.

The bodies of Dragon Flies are generally very long, slender, and
cylindrical, but in some species they are shorter, broader, and much
flattened. In the former case the number of segments is the same
as in the latter ; in fact the segments are so long in some species
that the abdomen presents a number of obttise angles when curved
under.

Some species lay their eggs on the stems and leaves of water
plants a little below the surface, and the long bodies are of service
here in allowing the operation to be performed without danger of
getting the thorax and wings wet.

The thorax is always broader than the abdomen, and, especially
in the slender-bodied species, is very deep from dorsal to ventral
surface, in order to accommodate the powerful muscles that move
the wings.

The head is large in proportion to the size of the body, but it
will be seen that the bulk of it consists of the eyes, which are not
only large and prominent, but so formed and disposed as to give the
creature a very wide range of vision. These organs too are gene-
rally most gorgeously coloured. The outer surface is highly polished,
and though apparently perfectly smooth when viewed with the
naked eye, may be seen to be regularly honeycombed when more
minutely examined.

Each little hexagonal area is a facet of one of the divisions of the
compound structure, and the whole outer structure is so transparent
that we can look into the interior and often witness a grand display
of brilliant colour, changing from one hue to another as we alter
the angle at which we view it. In some species the eyes are nearly
spherical, and situated at the sides of the head, with a considerable
space intervening ; but in others they meet in the middle line above,
looking like one continuous organ, and almost completely hiding the
other parts of the head when viewed from that side.

In addition to these large compound eyes, Dragon Flies possess
three simple eyes or ocelli, which are arranged in a row or form a
triangle on the front of the head. A pair of small antenne also
arise from the inner edges of the former.

AQUATIC INSECTS 247

It will be imagined from the above remarks that Dragon Flies are
especially gifted creatures as far as visual organs are concerned, and
as to their efficacy, no one who has ever watched one of these insects
on the look-out for flies can have any doubt. It will make straight
for an insect some distance off, and never fail to catch its victim, so
sharp is its vision and so powerful its wings.

The mouth of the Dragon Fly is a very complicated structure.
If we look at it when the insect is not feeding, it appears to have no
biting jaws; but poke a small stick or a piece of straw against the |
front of the creature’s head, and it will begin at once to bite away
savagely at the intruding substance, thus enabling us to observe the
different parts of its mouth.

At first sight it appears to possess jaws that move vertically, like
those of vertebrate animals, but a closer inspection will prove that
this is not the case. The parts referred to are really the lips, and
when these are brought together, the true jaws are quite concealed
beneath them. Then, while the insect is chewing, the large flat lips
are kept continuously moving up and down, thus giving the false
impression just mentioned. However, the true jaws—both maxille
and mandibles—are easily seen behind the lips. They are strong
and powerful, armed with toothlike processes, and work horizontally
as in all other chewing insects.

While thus engaged in tantalising the vicious Dragon Fly in order
to make it display its jaws, we can hardly fail to notice the extreme
slenderness of the neck, for the slightest pressure on the head is
sufficient to make it rotate on the thorax; and if the top of the head
be tilted forward, we see the neck itself, so narrow and threadlike
that it would appear quite inadequate to support such a massive
head.

In carrying out these observations we shall probably hold the
Dragon Fly between the finger and thumb, either grasping the thick
and firm thorax, or else pressing the wings together over the body.
In either case the insect may curl its abdomen below and forward
in a most menacing manner, just as a wasp or a hornet would
under the same circumstances; and the movement is so suggestive
of these hymenopterous insects that an inexperienced person would
instinctively avoid contact with the tip of the body for fear of being
stung. In fact it is probable that few, having caught a Dragon Fly
for the first time, would have the nerve to retain it a moment after
observing such a threatening attitude, unless previously advised of
the total absence of anything in the form of a stinging apparatus.

248 LIFE IN PONDS AND STREAMS

It may be mentioned, too, that the tip of the abdomen often termi-
nates in one or more sharp appendages, which add still more to the
menacing appearance of the insect when the above attitude is
assumed, for such appendages may be mistaken for stings by those
who are not acquainted with the true nature of these organs.

I have mentioned the beautiful colours displayed in the large
eyes of Dragon Flies, but equally brilliant hues are often reflected
by other parts of the body. Thus, the thorax and abdomen are fre-
quently most gorgeously tinted, the surface often giving brilliant
metallic reflections. But these, though a source of great pleasure
to observers of the living insects, are a cause of much disappoint-
ment to those who preserve the insects for the cabinet. In nearly
every case these beautiful colours fade away to ugly yellows and
browns, and sometimes change to black, the changes taking place
soon after the insects are dead.

There is no known method of preserving the beautiful colours of
these insects, but those of the abdomen may be in part maintained
by the removal of the contents. There seems to be no doubt that
the loss of brilliancy is due greatly, if not entirely, to decomposition ;
and this may be reduced considerably by slitting down the abdomen
along the under side and thoroughly clearing it of all its internal
parts. This is no easy task in the case of the small slender-bodied
species, but should invariably be carried out with the larger speci-
mens preserved.

Another source of trouble to the collector of Dragon Flies is the
extreme brittleness of the slender abdomens and of the narrow necks
when the insects are dry; but the only remedy here is care and
delicacy in handling the specimens, and also in avoiding anything
in the way of violent shocks, such as might be produced by the care-
less depositing of a store box, or the sudden closing of a drawer in
the cabinet. Of course the detached portions of a dried insect can
be easily replaced by the aid of a little coaguline or a suitable gum ;
but it is far better to take pains to study the prevention rather than
the cure.

The wing of a Dragon Fly generally consists of an exceedingly
thin and transparent membrane, and in some species this is deeply
and beautifully coloured. The principal nervures run from the base
to the tip of the wing, or curve round towards the hind margin.
Along the front margin the nervures with their branches are so
disposed as to form small square spaces or ‘ cells,’ and in some of
the small species the whole area of the wing is similarly divided up

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AQUATIC INSECTS 249

into square spaces; but in some species the reticulations become
much smaller towards the tip and the hind margin, and the spaces
have from four to six sides. Near the front margin of each wing
there is usually a slight bend, from which a short but strong nervure
passes backward. Also, near the tip of each wing there is generally
a dark spot called the stigma, sometimes elongated, sometimes short,
and often sharply rhomboidal. In some species the stigma is absent,
or represented by a pale spot.

In nearly all, the wings have polished and glistening surfaces,
which give a very pretty effect when the insects flit or sweep through
the air. In some of the small species the wings are so thin and
transparent that they would not be visible when the insects are
flying were it not for the flashes of sunlight reflected by their bright
membranes, and nothing would be .observable except the slender
body, floating like a thread wafted through the air.

Let us now repair to the haunts of the Dragon Fly. We choose
a scorching summer's day, and journey to some spot where isolated
ponds, whose banks are overgrown with semi-aquatic vegetation, are
distributed in the neighbourhood of a sluggish stream.

Before we reach the water we probably meet with a few of the
larger species, such as Cordulegaster annulatus, or the broad-bodied
Platetrum depresswm, which often wander far from the patch of
water that formed their home in search of food.

Here is one sailing backwards and forwards in a small wooded
glen, confining itself strictly to one little district not more than
twelve or twenty yards long, and following the same course as it
journeys to and fro, except when it makes a sudden dart to the right
or the left to pounce on some hapless insect that comes too near its
track.

Yonder we see another, engaged in a similar manner, and also
confining itself to its own chosen area.

We stand quite still, just in the middle of the course of one of
them, and carefully watch its movements. For some time it con-
tinues sailing up and down its track, its powerful wings never tiring
in the rapid flight ; and so fearless is it, that it takes no notice of
our presence, and even darts within a foot of us out of sheer bravado
or perhaps inquisitiveness.

Now a butterfly flits across its sacred track ; and the Dragon Fly,
with one steady but rapid dart, seizes the creature in its powerful
jaws, and continues its flight as before. Then down falls a wing,
which has been clipped from the butterfly’s body, like a faded leaf

250 LIFE IN PONDS AND STREAMS

a

on the moss below. Then another and another, till, in the space of
a few seconds, the Dragon Fly is feasting in the air on the wingless
trunk.

At last the voracious insect settles on a twig, and we approach
it stealthily, net in hand, feeling confident that now is ats turn to
become a victim. We find it quite motionless on its perch, and
prepare to strike ; but just then we hear a short rustling sound, like
the sudden shaking of a single leaf, and the Dragon Fly has disap-
peared. Its powerful wings had rustled against a leaf as it started
into the air, and its first dart was so rapid that we missed the
direction.

But it has not gone far. Here it is,in the same beaten track,
and now it alights again on the selfsame twig, apparently gazing
on its enemies at close quarters in pure defiance! We strike, but
miss our aim; and the creature seems more defiant than ever, for
it flies past us two or three times, approaching dangerously within
range, and then settles again almost within arm’s reach.

Another stroke of the net, and we have it! Its long wings lose
their freedom in the folds of the net, and so we secure it easily
between the finger and thumb, and transfer it to a dark box in which
it remains quiet, having lost the stimulus provided by the scorching
sun.

Now we approach a large pond the banks of which are overgrown
with flags and rushes. Here we see scores of smaller and more
delicate creatures resting on the leaves, but starting off with a more
feeble flight as we approach them, and soon settling again just a
few yards ahead. ‘These are easily taken in the net, often three
or four at one stroke, though many of them move to a safe resting
place on the rushes beyond our reach.

The scene is a very interesting one, for although these species
are too small to give any display of brilliant colours at a distance,
yet their glittering wings, airy flight, and floating threadlike bodies
have a very pleasing effect, especially when they appear in pro-
fusion, as they often do, round the banks of ponds.

But what a change when the shadow of a passing cloud sweeps
over the field! Not a single Dragon Fly is now to be seen on the
wing; but a careful search among the flags will reveal them at
rest, with their wings folded together just over their slender bodies.
And, having lost the stimulating power of the sun’s rays, they have,
alinost in a moment, become so sluggish and unwary that they may
be removed from their resting places by taking the wings between

AQUATIC INSECTS 251

the finger and thumb. But this period of lethargy is over as soon
as the shadow has passed and the bright rays again strike the pond.

In addition to these small and fragile species we shall probably
see one or two of a larger and sturdier build, flying gracefully but
swiftly forwards and backwards along the line of rushes, restricting
themselves each to the same limited beat, and seldom swerving
from the chosen path except to pounce on a passing insect. One
has to wield the net with great vigour to catch these powerful fliers,
and they often evade all our attempts by keeping over the water
just beyond our reach. |

We next stroll beside a sluggish brook the banks of which are
overhung with the boughs of bushes and the foliage of tall, herba-
ceous plants. Here our attention is attracted by a cluster of rather
large insects that much resemble the Dragon Flies we have already
seen in general form, but their wings are deeply coloured; and,
instead of isolating themselves and flying rapidly forwards and
backwards within a limited range, they sport about in the same
little nook, something after the manner of gnats.

Having now observed a few of the most striking features in the
structure and habits of Dragon Flies, we will briefly study the earlier
stages and metamorphoses. We have seen that the perfect insects
are not aquatic in the true sense of the term—that is, they do not
live in the water, but hover over or near it. But the term of the
imago is short compared with the total life, for nine or ten months
are occupied in the preparatory stages; and as the whole of this
time is spent in water, we must regard the study of the insect as a
necessary part of the work of the student of aquatic life.

As soon as the young larve are hatched, they find their way to
the bottom of the water, and there they remain, grovelling in the
mud and climbing on the low-lying weeds, till they are fully grown
in the following summer.

During their development they undergo a series of moultings,
but they never change much in form till the final transformation,
when the perfect insects emerge from the pupal skins. The wings
begin to appear at an early age, and the development of the insects
is so gradual, and the habits remain so constant throughout the
whole of the truly aquatic existence, that we have no well-defined
pupal stage.

Throughout the summer months, and in fact through nearly
the whole of the year, the larvee may be dredged out with the mud
and bottom weeds of nearly every pond and sluggish stream.

252 LIFE IN PONDS AND STREAMS

Among them we notice two distinct kinds, one with broad and
flattened bodies, and the other slender and fragile, with three
flattened appendages at the tip of the abdomen. The former are
the larvee of the large and powerful species, forming the families
Eschnide and Libellulide, and the latter are those of the small
and slender Agrionide. Both seem to delight in grovelling in the
dirtiest mud, and thrive well in stagnant ponds, the offensive odours
from which would repel any one other than the enthusiastic ento-
mologist.

We will describe the broad larva first. Its body is of a dirty grey
colour, so closely resembling that of the mud on which it lives that
it can lie unseen at the bottom, safe from its enemies, and a hidden
danger to the weaker and less destructive inhabitants of the water.
The surface of its body is very irregular, and generally covered
with a deposit of mud, which would of course add to the difficulties
of detection by those who would either attack or avoid it.

Its form, as well as its
colour, might be rightly
described as ugly. The
broad abdomen, which is
widest just behind the
middle, is very distinctly
Larva or Dracon Fiy, wirh segmented,and terminates
‘ Mask” EXTENDED behind in thick but sharp

spines. The thorax bears
six strong, spiny, sprawling legs, and rudimentary wings. .

The head is a very strange structure. It is big and broad,
with two short antenne, and two prominent eyes at the sides.
It is the mouth, however, that is most attractive from a structural
point of view. If we look at it from the front we see no jaws, for
the same reason that we cannot see them in the perfect insect,
except that in the present instance they are hidden behind a single
lip, and not behind two which move vertically and meet at their
edges.

The lip referred to is the lower, or labrum, which is here
developed to such an extent that it quite covers the front of the
head, and is therefore commonly known as the ‘mask.’ But it is
more than a simple covering for the face, for it is developed into a
long, jointed organ by which the insect seizes his prey.

In order to make out its structure we must push down the part
that forms the mask proper, and then ‘straighten out the lip, this

Fie. 213.

AQUATIC INSECTS 253

being easily accomplished by means of a stout needle. Now we see
that it consists of a long basal joint that is folded backward under
the thorax when the organ is not in use; also another part bending
forward, and widened and thickened in front, where it forms
moveable joints with the mask.

As to the mask itself, it consists of two distinct parts, arranged
side by side, and capable of two distinct movements. They can be
brought down from the face, so as to be in a line with the next
joint; and can also be moved laterally, just like a pair of jaws.
And they are virtually a pair of jaws, and the whole lip is used as a
prehensile organ, by means of which the larva seizes its prey.

Those who would like to witness the movements of this peculiar
appendage should secure a few of the larve in question, and place
them in a shallow aquarium where their habits may be observed
from above, a side view being often unsatisfactory in the case of a
creature that grovels in the mud. And it may be mentioned, by the
way, that the larve of Dragon Flies are not at all difficult to rear if
a little attention be given to their requirements. Put them into a
shallow pan or glass tank, together with the pond dredgings taken
in the net at the same time—mud and all, always including a little
vegetation. The mud will soon settle to the bottom, forming
just the kind of bed that the creatures like. Then keep them
supplied with aquatic larve, small worms and fishes, any living
creatures, in fact, not too large to be disposed of by the voracious
foes. There should be no difficulty in rearing the creatures till they
assume the perfect state; and in an indoor aquarium they will
remain more or less active all through the winter.

But to return to our study. Introduce a few aquatic larve, and
if the Dragon Fly larve have not recently partaken of a meal, you
may watch with great hopes of being able to witness a scene.

The Dragon Fly larva is so sluggish and clumsy in its movements,
at least as far as the legs are concerned, that it could never succeed
in catching very active creatures if it depended on these alone.
But it is seldom seen on the chase. It prefers lying in wait with
all the stealthiness of a cat, remaining quite still, and often half
buried in its muddy bed, thus awaiting its opportunity to strike.

Should an unfortunate creature pass within range, the mask is
straightened out with surprising agility, and at the same moment
the pseudo-jaws grasp the victim with such power that escape is
hopeless. Immediately the mask is retracted, thus bringing the
prey quite close to the mouth, and it is then rapidly devoured by

254 LIFE IN PONDS AND STREAMS

the aid of the true jaws, which are quite concealed behind the mask
when the latter is closed. ,

It may be observed that the ‘jaws’ which form the'mask proper
(these ‘jaws’ being the part of the lip that covers the face) vary in
form in different species. In the Libellulide they are broad tri-

Fie. 214.—Mask oF THE Dracon Fiy
Larva (Libellula) As SEEN FROM THE Fic. 215.—THE SAME VIEWED
SIDE WHEN ONLY PARTIALLY EX- FROM ABOVE
TENDED, ENLARGED

angular plates, hinged at the apices, and toothed like a saw at the
bases. They are also concave above (when the mask is extended),
and form, together with a concavity in the fore portion of the joint
to which they are fixed, a deep basin-like cavity, into which the
whole lower part of the head fits closely. When the ‘jaws’ are thus
closed over the face, the sawlike teeth fit so nicely into one another
that the division is hardly observable. These teeth, too, it need
hardly be added, serve to hold the prey firmly while the true jaws
are performing their task.

In other species the mask jaws are narrow and pointed—sickle-
shaped, and more like claws in appearance, and consequently do
not form such a complete covering for the face.

If we touch one of these larve when at rest, we shall observe
that it moves away from us with a sudden dart, sometimes without
the slightest movement on the part of its legs, just as though it
were urged forward by a propelling force acting behind. This in
itself is very puzzling, but a careful observation will reveal other
movements, evidently connected with this one, simultaneous with
it, which will furnish a clue to the mystery.

It will be seen that the abdomen is suddenly compressed just at
the moment when the larva darts forward, also that any particles
of mud or fine sand that happen to be close behind it at the time
are thrust backward. Also, during the intervals between the spas-

AQUATIC INSECTS 255

modic movements of the insect we may discern a gradual dilatation
of the abdomen, and even detect, by careful observation of small
particles suspended in the water, that a current is flowing into the
creature’s body through an aperture at the tip of the abdomen.

This solves the whole problem. When the abdomen dilates,
water flows in through the anal orifice, filling up the enlarged
rectum or hindermost portion of the digestive tube. Then, when
the insect is annoyed or threatened, it suddenly compresses its
abdomen by means of strong muscles, thus forcibly ejecting the
water, and the recoil or reaction urges the body forward, the prin-
ciple involved being exactly the same as that by which we explain
the kicking of a gun or the turning of a revolving water-spray.

But now let us watch the larva as it rests unmolested. The
abdomen is still pulsating, but slowly, and sometimes at rather long
intervals. The introduction of a very small quantity of a soluble
colouring matter, or of a solution of some pigment—which should be
placed in the right position, just behind the insect, by means of the
dipping tube—will show that water currents are passing gently in
and out of the body.

Again, if we watch the extremity of the abdomen while these
pulsations are in progress we may see the orifice opening or closing
as occasion requires. Around the opening are five thick spines,
three of which are much larger than the other two. Each time the
abdomen dilates, the spines turn away from the opening, and the
valvular flaps which guard it separate, thus allowing the current to
enter freely. And then follows the muscular contraction by which
the water is expelled, in this case slowly and gently, producing no
motion of the body as a whole.

Now what can be the object of this movement of water to and
from the interior of the abdomen ? This question is answered by a
careful examination of the walls of the cavity, aided by a low mag-
nifying power.

In the first place we may mention that the larva does not come
to the surface for air, but lives entirely at the bottom of the pond;
and hence it is clear that it must derive all the air it requires for
respiratory purposes from the water. Then, when we examine the
structure of the creature, and especially that of its tracheal system,
we find this conclusion confirmed ; for although the tracheal system
is well developed, there are no open stigmata at the surface of the
body, and hence all the air that enters the tracheal tubes must pass
from the water through their walls.

256 LIFE IN PONDS AND STREAMS

The walls of the rectum are drawn up into several folds, thus
increasing the area of the membrane that linesit. Then round this
membrane there are a large number of small tracheal tubes, which
are in communication with two main trache that run longitudinally
through the body, one on either side. Again, a number of other
tubes branch from these two and penetrate every part of the body.
Thus the whole tracheal system is brought into communication
with the water cavity of the abdomen.

When water is taken into the rectum, some of the oxygen it
contains in solution passes through the thin walls of this cavity, and
also through. the walls of the small air tubes that ramify on its
surface. This oxygen diffuses through the tracheal vessels of every
part of the body, and the carbonic acid gas that collects in the air
tubes passes into the rectum for expulsion.

The larve of the Agrionide, to which we have already briefly
referred as being of slender build, are not by any means so ugly
as those we have just described. In fact they are comparatively
pretty and graceful. Their bodies are often delicately tinted, and
taper gradually towards the ‘tail,’ which is ornamented by three
transparent leaflike plates.

These creatures are also much more active than the broad-
bodied species, sometimes walking about nimbly by means of their
six slender legs, and also swimming at times by vigorous undulations
of the body. In the latter case the appendages of the abdomen
are a great assistance. They are in fact the swimming organs, and
serve the same purpose as the tails of fishes.

The chief function of these appendages, however, is respiratory,
and their value as organs of locomotion must be regarded as of
secondary importance.

The larve in question do not take water into their bodies as the
others do, but the dissolved oxygen is absorbed, and carbonic acid
gas discharged, through the walls of fine tracheal tubes that are
thickly distributed in the thin plates. And, as with the larger larve,
these tubes communicate with the tracheal system, which sends its
ramifications to all parts of the body.

The pup of Dragon Flies are as voracious as the larve, and, as
before stated, differ but little in habits and structure from the latter,
except that the wings are more conspicuous.

When the time approaches for the final change, the insects may
often be seen climbing the pondweeds, and resting at the surface
of the water. Their stigmata are now becoming functional to a

AQUATIC INSECTS 257

certain extent, and they are no longer entirely dependent on the
dissolved oxygen of the water.

At this stage the insects should be watched at frequent intervals
by those who would like to observe the very interesting final meta-
morphosis. Of course there is a possibility
of witnessing this in the field; but one might
search for a long time round the bank of a
pond, even where Dragon Flies are very
plentiful, without seeing a single insect jusi
at the right moment. I have had this
opportunity myself on a few occasions, but
have always found it more convenient to
watch them in captivity; and then, after one
has had the insects under observation for yg 916.-Prpa or
some time, one knows when to expect the Dragon Fry
interesting event.

Let us suppose, then, that we have some pup in our aquarium
that appear ready for their final moult. We must see that they are
supplied with a suitable resting place out of the water. This may
be provided in several ways. You may obtain some semi-aquatic
plant, tall enough to stand well out of the water of the aquarium.
Plant this in a flowerpot of soil, and stand it in the middle. Ifa
suitable plant is not readily obtainable, one of the truly aquatic
plants that happens to be in the aquarium may be raised a little, so
that a portion of it, suspended by a thread, remains slightly above
the surface. Or objects of any kind, such as pieces of stick, strips of
calico, or pieces of string, may be suspended above the aquarium so
that they touch the bottom, or else rest on the tops of submerged
objects.

When the pupa is about to change, it creeps up out of the water,
and then remains quite still, save for a few slight movements of the
body that give one the idea of a creature ill at ease. Then, after a
short time, the skin, which is now loose on the body, gets dry and
splits. Almost immediately the insect shows evidences of its desire
to escape from its old coat, and it gradually frees its head and legs
by contorting the body. At last the head and thorax are quite free,
and it is not long before the perfect insect is entirely without its
pupal skin, which is still clinging by the claws to the object on
which the pupa rested. Thus the Dragon Fly leaves a coat, complete
even to the skin of the legs and claws, and often so perfect that it
might easily be mistaken for the former occupant.

258 LIFE IN PONDS AND STREAMS

But now let us watch the Dragon Fly itself. Its body is very
soft, and its newly exposed skin moist and flexible ; and the creature
is, for the time, quite helpless. ‘The wings are small, creased, and
unsightly ; and so soft that they bend with the slightest pressure.

A change soon takes place, how-
ever. The wings gradually expand
and straighten out, but are still soft
and useless for flying. But they,
and also the skin, rapidly become
dry in the sun; and it is not long
before the creature releases its hold
and takes its first flight into the
air.

CLASSIFICATION OF DRAGON FLIES

Dragon Flies are divided into two
main groups, the Libellulina and
the Agrionina. The members of
each group may be very readily
distinguished by the form of the
head, which in the former is mas-
sive, and rounded in front; but in
the latter is small, and very wide

Rig Ot ecaon are from side to side. There is also a
EMERGING FROM THE Pupa Case ready means of distinguishing be-

tween the two divisions in the
wings, the hind pair in the case of the insects of the first group
being very wide at the base, while all four wings of those of the
second group are narrow at the base. Nor is there any risk of
confusing these two groups in their earlier stages. We have
already referred to two distinct types of the larve of Dragon Flies,
the one distinguished by a short and broad abdomen, and a respira-
tory cavity formed by the enlarged rectum, surrounded by a number
of fine tracheal tubes; and the other with a slender body, termi-
nating in three leaflike respiratory plates. The former is a type
of the Libellulina, and the latter of the Agrionina.

The Libellulina is subdivided into two groups—the Libelluline,
with head about the same width as the thorax, and the ocelli
arranged in the form of a triangle ; and the A/schnine, with head
wider than the thorax, and the ocelli placed in a straight line,

“MUNN 0 : \

AQUATIC INSECTS 259

These, again, are divided into families, the Libelluline into two
families—Libellulide and Corduliide; and the A’schnine into
the Gomphida, Cordulegastride, and the A?schnide.

Similarly the section Agrionina is divided into two families—
the Calopterygide, with broad and beautifully coloured wings ; and
the Agrionide, with narrow and transparent wings.

It would be uninteresting to enumerate here all the chief dis-
tinguishing characteristics of the various families, genera, and
species of the whole of the British Odonata; but nevertheless such
particulars are essential to aid those who would study the relation-
ships of the insects, and would arrange their specimens in the
cabinet in their proper order.

I shall therefore supply sufficient information to enable the
reader to identify and arrange his specimens, putting the same in a
tabular form, so as to be convenient for ready reference.

Before doing this, however, it will be necessary to explain a few
terms that will be used, not that the actual terms are absolutely
necessary to enable one to correctly describe the insects in question ;
but they are very convenient, since they allow us to express our-
selves in a very concise manner.

First, with regard to the head of the Dragon Fly, we have already
observed that the large compound eyes form the bulk of it. When,
however, the colour of the head is spoken of,
the eyes are not included, and the note is
intended te apply only to the space between
them. The simple eyes, or ocelli, are placed
on the crown of the head, and the arrange-
ment of these is in some cases important,
as it assists us in distinguishing between
species. It will be observed that in the yg a9 ee rs

case of Platetrum depressum—one of our Platetrum depres-
commonest species (fig. 218)—the large com- sum, ENLARGED ;
pound eyes meet in the middle line above, SHOWING THE LARGE

nia h s that tl wears f CompounD Eyes,
occupying so much space that the crown o cok’ Conti aia
the head is very small. When the eyes ANTENNE

meet in this way, they are said to be con-
tiquous. Our illustration also shows the arrangement of the
three ocelli, and the short antenn arising from the inner edges of
the compound eyes.

Fig. 219 shows the arrangement of the same parts in another
common species—Cordulegaster annulatus. Here the compound

8 2

260 LIFE IN PONDS AND STREAMS

eyes also meet, but are narrowed down to such an extent towards
the inner side that they only just touch at a point; and the ocelli are
arranged ina line. In other species of the same tribe (A’schnine)
the head is similar except that the compound eyes do not touch
at all.

Fic. 219.—Herap or Cordulegaster
annulatus, ENLARGED virgo, ENLARGED

Our next sketch illustrates a marked difference, for the head is
very wide in proportion to its length, and the large globular eyes
are very remote, being placed on the extreme sides of the head.

We will now examine the wing of a Dragon Fly, making use of
an enlarged sketch that we may better delineate the delicate nervures
or wing rays.

Fic. 221.—Hinp Wixe or Cordulegaster annulatus, ENLARGED

1, costal nervure ; 2, hind margin ; 3, tip; 4, anal angle; 5, base; 6, stigma; 7, cubital
point ; 8, principal radius; 9, medial radius ; 10, triangle

That portion of the wing which is joined to the body is termed
the base. The front margin is the costa, and is supported by the
costal nervure ; and the opposite edge is termed the hind margin.
In this particular wing there is an angle at the hind margin, close
to the base, and this is called the anal angle. Close to the base,
between it and the anal angle, is a membrane called the accessory
membrane. On the costal margin, near the apex of the wing, is an
elongated black spot called the stigma. About halfway between
this and the base of the wing there is a point marked by a short but

q

AQUATIC INSECTS 261

strong transverse nervure: this point is known as the cubital
point. It will be seen that there are about twelve or more short
transverse veins between the cubital point and the base of the wing,
each running from the costal nervure to another parallel with it,
thus dividing the long and narrow intervening space into so many
little square areas. An observation of the number of these little
nervures is often useful when identifying and classifying the different
species. Further, it will be observed that a few of the principal
nervures run direct from the base of the wing to the tip and the
hind margin. These are called radial nervures ; others, branching
from them, and running uninterruptedly to the hind margin,
dividing the wing into large segments, are called sectors.

It is interesting also to note the different shapes of the very
small areas of the wing enclosed -by the smallest nervures. Many
of these, especially near the costal margin, are four-sided ; while
the smaller ones towards the tip and the hind margin have five or
six sides.

Near the base of the wing there is a very conspicuous triangular
space, enclosed by three strong nervures, with its apex directed to-
wards the hind margin. This area is termed the triangle, and in
the case of C. annulatws—the species of which
the wing is figured—it is divided into smaller
areas by a delicate transverse nervure.

When describing the form and colour of the
different species of Dragon Flies, it will be fre-
quently necessary to mention the segments of 4
the body, calling them by their numbers ; and,
in order to avoid mistakes in this direction, it
is desirable that some attention should be given
to the general build of the body of these insects.

The illustration (fig. 222) represents the
abdomen of one of the Corduliida (Cordulia
enea), enlarged, and with some of the seg-
ments numbered. As regards the thorax, it 10
will be remembered that it has three segments,

each bearing a pair of legs; and that the Fic. 222.—Bopy or
Cordulia nea,
ENLARGED, SHOW-

be |

wings are attached to the second and third

segments. The abdomen, it will be seen, ING THE SEGMENTS
. wb oS sa .
consists of ten segments, and these are gene- OF THE ABDOMEN

rally so distinct in the Dragon Flies that it is
not at all difficult to make them out. The tenth segment usually

262 LIFE IN PONDS AND STREAMS

bears two pairs of appendages, the form and arrangement of which
vary in the different genera.

In C. enea the upper appendages are cylindrical in form, while
the lower are curved like a clawand deeply
notched. In Platetrwm depresswm they are
very small and inconspicuous. ‘Those of
Aischna cyanea are long and flattened in the
S male, shorter and narrower in thefemale. In
Fic. 223.—Tue Ap- Lestes sponsa the upper ones are curved like

DOMINAL APPEN- a pair of pincers, and toothed on the inner

paces or Cordulia side; and the lower straight and narrow.

bar Bae a aa Having called attention to these few
particulars, we will proceed with. our table of the families.

Table of the Families of Dragon Flies
I. Head large, and rounded in front. Hind wings broad at the
base. Larva with short and broad abdomen.
(Section LiBELLULINA.)
A. Head about same width as thorax. Ocelli arranged in a
triangle.
1. No metallic colours. Family LIBELLULIDA.
2. Abdomen club-shaped. Metallic colours.
Family CORDULIIDAL.
B. Head wider than the thorax. Ocelli in a line.
5. Eyes not contiguous. Family GOMPHIDA.
4. Eyes just meet at a point.
Family CORDULEGASTRIDA.
5. Wings broader. [yes contiguous.
Family ASCHNIDA.
II. Head small and wide. Eyes very remote. Abdomen
slender. Larva long and slender, with three flat abdominal appeén-

dages. (Section AGRIONINA.)
6. Wings wide and deeply coloured. Bright metallic
colours. Family CALOPTERYGIDAS.

7. Wings narrow and transparent. Only two nervures on
the costa before the cubital point. Family AGRIONIDAS.
Family LIBELLULIDA

This family contains thirteen British species, but only four of
these are really common insects. In one case (that of Lewcorrhinia

AQUATIC INSECTS 263

pectoralis) the insect has been placed on the British list on the
strength of one single specimen, which was taken near Sheerness
about thirty-five years ago. Of Sympetrum meridionale, only a
few specimens have been taken, and these near London; and of
S. Fonscolombu, only three.

It is interesting to note that insects which are placed on British
lists on the strength of one or two captures are generally taken in
the extreme south, and, moreover, belong to species which are more
or less abundant on the other side of the Channel. Hence we have
reason to believe that they are not true natives of Britain, but
consist of specimens which have strayed or have been blown over
from their own country, and their appearance in our maritime
counties ought rather to be regarded as accidental.

It is only fair to add, however, that such may not be the case—
that the specimens taken were insects which were born and bred in
our own ponds; and even the youngest of our pond-hunters should
keep on the watch for such rarities, for it is possible that he may
not only become the fortunate possessor of one of these gems, but
that he may also gain such experience as will enable us to claim
these rare insects as our own, or even add fresh species to our
Odonata.

One of the commonest species of this family is Platetrum
depressum, the female of which is figured on Plate IV. Itisa
powerful insect, with a broad, flattened abdomen. It strays far from
the water, and may be seen sailing backwards and forwards in
wooded places, often confining itself to one small tract.

So defiant is it when attacked with the net, that it sometimes
seems advisable to strike when there is really no chance of reaching
it, for it will often make a nearer approach after the first assault, as
if to challenge your skill; and will sometimes, after darting by you
two or three times, suddenly alight on a twig quite within the range
of your net.

Chase is perfectly hopeless with the largest and most powerful
insects of this family. Your only chance is to stand in wait, striking
when a good opportunity occurs, and stealthily following them up
when they show an inclination to settle.

Another peculiar feature of this and some of the other large
Dragon Flies is their great tenacity of life. Many instances of this
have been recorded, but the most remarkable case that ever came
within my own experience is the following:

On one occasion I struck at a Depresswm as it was flying past.

264 LIFE IN PONDS AND STREAMS

I was successful, or at least partially so, for on examining the net
I found that I had the creature, minus its abdomen. The hoop of
the net had struck it, severing the body at the waist, and enclosing
the fore portion only. The thorax and head were quite uninjured,
and the wings were intact. After examining the half-insect for a
time, and noticing with surprise how little it seemed to care for the
loss of such a large portion of its anatomy, I placed it on the ground.
Immediately it began to fly, but it could not balance itself well,
and was easily caught again. Just then I caught a large fly that
had caused me some little inconvenience by persistently settling
on my perspiring face ; and, without anticipating the result, held it
close to the jaws of the Dragon Fly. Without a moment’s hesitation
the creature began to chew vigorously, and soon devoured the
whole of the fly with the exception of the wings. I was previously
well aware of the fact that some species of Dragon Flies will eat
readily from the hand as soon as they are captured, and while still
held in the captor’s hand, but this was a decided advance on such
indifference, for here was an insect taking food, apparently with a
relish, and having no stomach in which to digest it! And this is
not, I believe, an isolated case of its kind, for I have heard of others
who have had similar experiences with the larger Dragon Flies.

It is doubtful, to my mind, whether the act just referred to on
the part of Dragon Flies is prompted by hunger or sheer savagery ;
for they will chew up a straw or any other such substance pre-
sented to their powerful jaws. It should be noted, however,
that they will generally swallow parts of the flies that may be
presented to them, while the chips of straw &c. are allowed to fall
to the ground.

teturning again to the unfortunate Depresswm mentioned
above, it should be mentioned that the fly given to it was actually
eaten, and fragments of its body were seen to emerge at the back
of the thorax. And, further, the Dragon I'ly seemed so unconcerned
at the loss of its abdomen, that there appeared to be no immediate
need to kill it in order to terminate what might be supposed to be
a painful existence. So I boxed it, and, on arriving home, placed
it in a large vivarium. Here it remained comparatively quiet for
nearly two days, after which time a brilliant sun roused it to
activity. But its glee was cut short; for a green lizard, occupying
the same case, attracted by its attempts to fly, soon attacked it,
and seemed to enjoy the meal, except that it had considerable
difficulty in disposing of the large and broad wings.

AQUATIC INSECTS 265

The general characteristics of P. depresswm may be observed
in the illustration on Plate IV (fig. 1), where the female is figured.
The male differs in having the abdomen covered with a cobalt bloom,
and yellow spots exist on the sides of the middle segments only.

This species, as well as other common insects of the same
family, is often called the ‘ horse-stinger’ by the country folk, who
will declare that they have seen it sting horses as they feed in
meadows or as they walk through the lanes. But there is not the
slightest foundation for the name, nor can there be any other than
purely imaginary reasons for the statements made.

Libellula quadrimaculata (fig. 224) is another well-known
insect of the same family. It is not so generally distributed as

Fie. 224.—Libellula quadrimaculata

P. depressum, but it is often very abundant where it occurs. Those
who live in the metropolitan district should search for it in Epping
Forest, where it is tolerably plentiful; and the New Forest—a famous
hunting-ground for entomologists—is also one of its favourite resorts.

It varies considerably in brilliancy of colouring. In fact there
are two or three distinct varieties of the species. It may be dis-
tinguished. from the last species by its narrower and tapering
abdomen, also by the presence of a dark spot on the middle of the
costa of each wing.

There are also two common species belonging to the genus
Sympetrum, both of which are considerably smaller than the two
previously named. One of them—S. vulgatum (tig. 225)—is most

266 LIFE IN PONDS AND STREAMS

abundant in the southern counties, while the other—S. scoticwm (fig.
226)—abounds more in the north; but both are generally distributed

Fig. 225.—Sympetrum vulgatum

S. vulgatum is about an inch and a half long, and two and a
quarter inches in width, from tip to tip. The thorax is of an olive-
brown colour, with three black stripes on each side; and the abdo-
men is reddish olive, marked with yellow between the segments.

S. scoticum is much smaller, being less than an inch and a
quarter in length, and only two inches across. The head, thorax,
and abdomen of the male are all of a blackish colour tinged with

Fic. 226.—Sympetrum scoticum

purple, and the eyes green. The female is olive, except the hinder
half of the eighth,and ninth segments, which is black. The wings,
especially the hind pair, are slightly tinted with yellow.

Other species of this family may be taken by the young collector ;
but as it is impossible to give descriptions of all, we append a table
which will enable the reader to classify his captures.

AQUATIC INSECTS 267

Family LIBELLULIDA®

I. Antecubital nervures ten to sixteen in number.

A. Abdomen broad and flat. Genus PLATETRUM.
B. Abdomen thick, tapering. Genus LIBELLULA.
C. Abdomen cylindrical. Genus ORTHETRUM.

II. Antecubital nervures six to eight. Length of body an inch
and a half or under.
D. Dark spot at base of wings. Genus LEUCORRHINA.
E. No spot at base of wings. Genus SYMPETRUM.

The reader should first determine the family to which his
captures belong, by the help of the table on page 262. Having
settled this matter, he should place each in its proper genus, making
use of the small tables given under the heads of the families.

In the case of the present family the following notes may prove
useful :

The genus Platetrum contains only one British species—
P. depressum.

The second genus (Libellula) contains two; one, L. quadri-
maculata, which may be known by the spots on the middle of
the costa of each wing; and the other, L. fulva, a very rare species,
without such spots.

In the genus Orthetrum there are also two species, but both very
local in their distribution, especially O. cancellatum, which may
be recognised by the brown accessory membrane. In the other
(O. caerulescens) this membrane is white.

As regards the genus Leucorrhina, the young collector can
hardly expect to secure a representative ; for besides L. pectoralis,
of which, as we have already pointed out, only a single specimen has
been taken in Britain, there is only one species—L. dubia, which
is exceedingly rare.

The last genus—Sympetrum—contains a few smaller insects,
none of which exceeds an inch and a half in length. The smallest of
these is S. scoticum, and this species and S. vulgatum have already
been named as the only two of the genus that are generally dis-
tributed. S. flaveolumand S. sanguineum are both very local. The
latter may be known by the blood-red stigma, and the former by its
black nervures.

Two other species have been added to the British members of
this genus on the strength of two or three recorded captures.

LIFE IN PONDS AND STREAMS

bo
oo
CO

Family CORDULIIDA&

We have only three species of this family, and they represent as
many genera. They are all beautiful insects, being rendered so by
the brilliant metallic hues of their bodies.

One only of these is likely to be seen at large by young collectors,
but it is possible that one or both of the others may be taken.

The commonest species is Cordulia eanea (Plate V, fig. 1), the
head, thorax, and abdomen of which are all of a beautiful brassy
green colour. The eyes are also green, and the mouth yellowish
brown. The wings are stained with yellowish brown at the very
base, and those of the female are very slightly stained with brown
throughout.

It will be observed that the triangle of the forewings is not equi-
lateral, and that a strong nervure runs from the middle of the base
to a point very near the apex, on the outer side. Other nervures
are usually present within the triangle, but these are not by any
means constant.

The abdomen of 4?nea is also club-shaped.

This beautiful insect is moderately common in the south and
south-eastern counties. I have taken several within a few miles of
London.

Although the other two species of this family are rare, yet I
include a little table which will serve for their identification, hoping
that the reader may be so fortunate as to require its aid.

Family CORDULITDAL

I. Triangle of forewings not equilateral, and crossed by a trans-
verse nervure.

A. Face with yellow spots. Genus SOMATOCHLORA.

One species (very rare). S. metallica.

B. No yellow spots on face. Genus CORDULIA.

One species (generally distributed). C. enea.

Il. Triangle of forewings equilateral, and having no transverse
nervure. Genus OXYGASTRA.
©. One species (very rare). O. Curtist.

It will be interesting to note here that the last of these species is
to be found in Britain alone, and, being also very rare, would be
regarded as a great acquisition by any entomologist. It is to be

AQUATIC INSECTS 269

hoped, however, that, should a collector happen to find the insect
tolerably plentiful in any locality, he will not be tempted to take life
unnecessarily for the purpose of merely adorning his cabinet. The
total extinction of this beautiful insect would be deemed a great
loss by all true lovers of insect life.

Families GOMPHIDA and CORDULEGASTRIDA

The first of these families is not likely to come within the ken of
the reader, for it contains only three species, two of which have been
added to our list through the capture of a single specimen. The
third (Gomphus vulgatissimus) is very rare and very local, having
been taken in but few localities in the southern and south midland
counties.

This species is nearly two inches in length, and a little over two
and a quarter across. The wings are entirely transparent, with
stigma of a bluish colour; and there is a deep notch at the anal
angle. The head is brown, and crossed by three black lines, and
the eyes are of an ashy grey colour. The thorax is yellowish, with
two dark lines above, and two others on each side. The abdomen
is marked with black and yellow above, and spotted with yellow at
the sides.

Of the Cordulegastride we have only one species, but this a
moderately common Dragon Fly. Itis very widely distributed, but
seems to favour only certain localities. I have taken several in the
wooded hills in the neighbourhood of Bournemouth, particularly on
the slopes of the branksome Chine.

It is a very rapid flier; and, like Depressum and other large
species, it confines its ravages to one particular limited area, darting
to and fro after its insect food, often skimming the surface of the
water, but sometimes confining its attentions to a little track of
wooded ground some distance from the nearest pond or stream.

The species to which we refer is called Cordulegaster annulatus
(Plate IV, fig. 2), and it is, both as regards size and colour, a really
fine insect.

Its body measures about two and three-quarters of an inch in
length, and the width from tip to tip is quite three and a half inches ;
but a variety of the species that is considerably smaller is occasion-
ally met with. The head is yellow; the thorax black, with three
golden yellow stripes on each side, and two, placed obliquely, above.
The abdomen is club-shaped—a feature which has given rise to the

270 LIFE IN PONDS AND STREAMS

generic name, for the word ‘ cordulegaster’ signifies ‘ club-bellied.’
The general colour of this portion of the body is black or dark
brown, but most of the segments are variously marked with a bright
golden yellow. ‘The first segment is yellow at the sides ; the second,
before and behind; the third, fourth, fifth, sixth, and seventh,
across the middle ; the others are entirely dark with the exception
of small dots on the last but one. The wings are transparent in all
parts with the exception of the usual stigma.

Family AU0SCHNIDA

This family includes eight British species, all of which are large
insects; but only two of these can be described as common, and it is
feared that one of them—schna rufescens—is very nearly extinct.

The typical genus contains two fine insects that must have
exhibited their masterly flight to all frequenters of the country.

One of these—Aischna grandis—is often to be seen during July
in all kinds of localities, for it frequently strays far from the water
which formed its home during the earlier stages of its existence, and
even ventures into gardens in the midst of our towns. It seems
very partial to woods, and will often fly high among the topmost
branches of tall trees, and settle there at times to devour its prey.

The body of this insect is two and three-quarters of an inch
long, and the wings measure nearly four inches across. The head
and thorax are red, the latter with two yellowish patches on each
side. The abdomen is also red, spotted with blue in the male and
with yellow in the female. The wings are stained with brown, and
the nervures are of an orange colour. |

The other species referred to is 4’. cyanea, and this one is still
more common. Like the preceding insect, it frequents all manner
of localities, and it is also similar inits habits. Such powerful fliers
as these are not easily taken in the net, and they often make a dart
over the tops of tall trees when attacked. A very bright day with
passing clouds is the best for the hunter of these creatures. As long
as the sun shines brightly they keep actively on the wing, and a
sharp eye is required to follow their movements. But as soon as
the shadow of a dense cloud covers their beat, they settle on a twig
to rest. If, now, the observer has been fortunate enough to see
where one of them alighted, he should have little difficulty in
securing it with a sharp sweep of the net.

48. cyanea may be distinguished from 4’. grandis by the bright

AQUATIC INSECTS 271

greenish blue eyes, and the two large oval greenish spots on the front
of the thorax. The abdomen of the male also is spotted with greenish
blue, but the spots of the female are yellow. The wings are stained
with yellow, and the stigmata, which are shorter than in 4. grandis,
are black in the male and brown in the female.

———
a5 jsoeane
THES

by

eT ON
A Slay aang

PAW Woe ic

Fic. 227.—A’schna cyanea

Af. juncea, unlike most of the Dragon Flies, is more abundant
in the North than in the South ; and is found to be far more plenti-
ful in Scotland and Ireland than in England. It is not so abundant
as the two members of the same genus just mentioned, but is plenti-
ful in some northern localities.

The thorax of this species is brown, with two very broad yellow
oblique stripes at the sides, and two narrow ones in front, the latter
being broken in the female. The abdomen is spotted with blue in
the male and with pale yellow in the female. The wings are stained
with brown, and the stigmata are long and narrow.

There are two other species in this genus, One of them,

bo

72 LIFE IN PONDS AND STREAMS

E. borealis, has been taken only in Perthshire; and the other
A). mixta, though widely distributed, is regarded as a rarity.

The former has blue lateral and front stripes on the thorax, and
the abdomen is spotted with blue in the male and with yellow in
the female. The latter has the thorax spotted and striped with a
yellowish colour. The abdomen is brown, with black bands, and
is marked with yellow in the male and with green in the female.

The remaining species of the family are Brachytron pratense
—a very local insect, the whole body of which is hairy; and Anaz
formosus, which is the largest of all the British Dragon Flies, also
very local, but widely distributed.

Family CALOPTERYGIDA

No one could possibly mistake the members of this exceptional
family. It contains only two species, and both these have very
broad and coloured wings. These wings, however, are not wide at
the base, like those of the Libelluline, and there is no anal angle.
The neuration of the wings is exceedingly delicate, and the bodies
are adorned with brilliant metallic hues.

The country folk often show their appreciation of the beauty of
these brightly coloured insects by naming them ‘ Kingfishers,’ and
the French honour them with the title ‘ Demoiselles.’

There is a very great difference in the general habits and flight
of the Calopterygide and those of the various Dragon Flies pre-
viously mentioned. Most of the latter remind us of the powerful
and rapacious birds of prey, while the former are more fitting
emblems of the small, brightly coloured and social song-birds.

They are seldom seen singly, but dance about in the air in little
groups, something after the manner of gnats, and generally remain
immediately éver the water of a stream or pond, apparently far
more attentive to their frolicking games than to the numerous
insect delicacies that swarm in the immediate neighbourhood.

Their flight is so weak, and their habit of remaining in one re-
stricted spot is so persistent, that there is no difficulty in catching
them, provided they are within reach of the net ; but they frequently
tantalise the collector by hovering over the middle of a stream that
is just wide enough to prevent them being within range from either
bank.

I have often found it necessary to cut a stick, several feet in
length, to tie to the stick of the net in order to make it sufficiently

PLATE YV.

5

Danielsson & Co., London, del. ad. Nat. et Chromolith,

|

AQUATIC INSECTS 273

long for this purpose ; but the instrument, though more or less suc-
cessful after being thus lengthened, is very awkward, and of course
cannot be swept so rapidly through the air. Another difficulty is
sometimes experienced by the selection, on the part of these insects,
of a nook protected by tall and overhanging vegetation that greatly
interferes with the vision of the naturalist as well as with the move-
ments of the net.

There are two British species of this family—Calopteryz virgo
and C. splendens. They are both of the same dimensions, the body
being about an inch and three-quarters long, and the breadth from
tip to tip two inches or more.

The head and thorax of C. virgo (Plate V, fig. 2) are of a brassy
green or blue colour. The abdomen is also generally of the same
hue, but sometimes of a rich coppery red. The wings of the male
are bluish black except at the base and the apex, where they are
transparent and yellowish, and there are no stigmata. Those of the
female are brownish, and have a white stigma some distance from
the tip.

It should be noted, however, that this species is subject to much
variation. Sometimes the wings of the male are brown or smoky,
and those of the female are occasionally tinged with green.

This is one of the earliest of our Dragon Flies. It sometimes
appears early in May, but June and July are good months in which
to search for it; and I have taken several specimens in the New
Forest as late as the last week in August.

C. splendens is a very similar insect. The head and body are of
the same colour, but the wings are narrower, and with even finer
reticulations. Those of the male are yellowish and glassy, with a
broad central patch of bluish black. Those of the female are pale
green, and the white stigma is nearer the tip than in C. virgo.

Family AGRIONIDAE

This is the last and the largest family of our Dragon Flies, but
all the species are small, none of them exceeding an inch and a half
in length arid one and three-quarters across. In all of them the
wings are narrow and transparent, and the stigma is rhomboidal in
form, the outer and inner edges sloping backwards and inwards.

Of the fifteen species that have been entered on the British list,
there are three that have a claim to be placed there only on the

T

274 LIFE IN PONDS AND STREAMS

strength of one or two captures. Five may be described as common,
and all the others are more or less local and rare.

Their flight is short and weak, hence they are easily captured
with a net when on the wing ; but being so very slender and fragile,
it requires an experienced eye to follow their movements in bright
sunshine. The exceedingly slender bodies, almost invisible at even
a short distance, and the colourless wings are rendered apparent
only by their reflection of the sun’s rays.

These Dragon Flies seldom stray far from the water in which they
spent their earlier days, but usually flit about among the flags and
other semi-aquatic plants round ponds and on the banks of sluggish
streams. In the case of damp meadows and marshy ground they
are less restricted, and may be found settling on rank herbage in all
directions, and sometimes seek the shelter of the neighbouring
hedgerows.

In dull weather they are very sluggish, scarcely moving at all,
but remaining at rest on the herbage with all four wings folded
together over the back. At such times they may be lifted from
their resting places by the wings and boxed at pleasure.

The commonest species of the largest genus (Lestes) is L. sponsa
(Plate V, fig. 3); and so plentiful is this one in certain localities that
almost every flag and rush supports one or more, and as they flit
about in the sunshine a dozen or so may be taken in the net at one
sweep.

The head, thorax, and abdomen are all of a metallic green colour,
except that the last two segments of the male are blue. The upper
abdominal appendages are curved like a pair of pincers, and the
lower ones are straight. The stigmata of the wings are black.

Another species of the same genus—L. nympha—is widely dis-
tributed, but very local. Its body is of the same colour as that of
L. sponsa, but the male is powdered with blue, and the stigma of
the wing is smaller than in the last species.

The typical genus (Agrion) contains three interesting species.
Of these A. puella (Plate V, fig. 4) is very common and generally dis-
tributed, and, like L. sponsa, literally swarms in some neighbour-
hoods. The male is blue and marked with bronze colour, but in
the female the ground colour is bronze and the spots blue.

This insect appears on the wing in May, and continues to fly tall
about the end of July.

Agrion pulchellum is also widely distributed. It is more local
than the last species, but is very abundant in many places. Its

AQUATIC INSECTS 275

body is bronze-coloured, spotted with blue. The female has two
little spots on the hindmost part of each segment of the abdomen.

The other insect of this genus is A. mercuriale, which is the
smallest of all the British Odonata.

Enallagma cyathigerum (Plate IV, fig. 3) is another of our com-
mon Agrionide, and the only one of its genus. Its body is bronze,
spotted with blue, and the stigma of the wing is rhomboidal in form,
and short. This species is common in the North.

Two others must be mentioned, and these are the common
Pyrrhosoma minium (Plate IV, fig. 4), readily known by the bright
red body ; and Ischnura elegans, the abdomen of which is black with
the exception of the eighth segment, which is blue. In both these
species the stigma is small and rhomboidal. The former is a very
common insect ; the second also is common, but more local.

May Furies (Ephemeride)

On a summer’s evening, late in May or in the beginning of June,
we may see swarms of flies, with delicate gauzy wings that measure
an inch or more across, dancing up and down in the air over the
edge of a stream or large pond, and often touching the surface of
the water with very long filamentous appendages that arise from
the tip of the abdomen.

Their merry movements continue in the dusk till we can no
longer distinguish their fragile forms; but still we are aware of their
presence ; for, as we walk along the path by the water’s edge, we
now and again come into contact with a group of them, and feel
the rustling of their fragile wings and the sweeping of their slender
filaments on our faces.

If we happen to be on a nocturnal entomological hunt, and
possess the lantern so essential on such occasicns, we throw our
light towards the water, and then they approach from the darkness,
attracted by the gleam, and even play against the glass.

On the following morning we visit the spot again, but the swarms
have disappeared. However, on examining the flags and other
herbage, we may succeed in finding a few at rest. So sluggish are
they now that they are easily taken by the wing between the finger
and thumb. A few fly as we approach them, but only to settle
again immediately on some neighbouring plant.

Later in the day, when the sun is high, we walk over the same
ground again, but all have disappeared.

T2

276 LIFE IN PONDS AND STREAMS

In the evening we witness the same sight again, and perhaps
for an evening or two after; but their numbers rapidly diminish,
and no more are to be seen till the corresponding season of the
following year. ,

These insects are known as May Flies (Ephemeride), and their
sudden appearance in countless swarms, their equally sudden dis-
appearance, and the remarkable peculiarities of their metamor-
phoses, have made them objects of attraction to naturalists from
very early times.

The perfect insects are very fragile creatures. They have two
pairs of wings, the front ones being long and broad, but the hind
pair very small, and in some species quite rudimentary. _

The antenne are short and inconspicuous, but the front pair of
legs, which are very long and slender, are thrown forward when
the insect flies, so that they look just like a pair of long antenne.

At the tip of the abdomen there
are two or three very long hairy
appendages, generally much longer
than the body of the insect, and so
fine that they are hardly visible as
Bea it flies.

When we look closely into the
structure of the wings we are re-
minded at once of those of the
Dragon Fly, for they consist of a
delicate transparent membrane,
supported by a fine network of
nervures. The chief nervures ex-
tend from the base of the wing to
the tip and hind margin, running
almost parallel with one another ;
and the lesser ones join these at
Fic. 228.—May I'iy (Ephemera right angles, thus dividing the mem-
vulgata) brane up into a number of little
four-sided cells, which are smallest
at the tip and along the hind margin, and comparatively large at
the base and in the middle of the wing.

Like other insects, the May Fly is provided with a pair of com-
pound eyes; but the organs of the mouth, which, we have seen, are
so well developed in Dragon Flies, and which, even in the Bugs, form
a complicated suctorial organ, are here in such a rudimentary. form

> PPP erhikeey)

|

AQUATIC INSECTS 277

that the insect is practically mouthless. It has not the slightest
power of taking food of any kind; and, after all, this is not surpris-
ing when we consider the very brief duration of the winged state.
As a larva, it fed, and fed well; and during the many long months
spent in the mud as a grub it stored up just sufficient energy to
enable it to perpetuate its species, for which purpose alone it assumes
the winged state.

The eggs are laid on the surface of the water, the whole batch
from one female being deposited at the same time. They are
slightly heavier than their own volume of water, and therefore
sink immediately, but slowly. Again, they are not glued together
like those of so many other insects that lay their eggs in a cluster,
hence they become scattered as they descend ; and the dispersal is
aided by the peculiar form of the eggs, which are little flattened
discs. Were they of a globular form, they would of course sink
perpendicularly unless drifted by the force of a current, and even
then all would keep fairly well together, being impelled by the same
force. But as aresult of the greater resistance offered by their
flattened faces, they spread out in all directions.

The young larve, as soon as they escape from the egg, burrow
into the mud at the bottom of the stream, just as though they were
quite aware of their defenceless condition, and of the numerous
enemies always ready to pounce on such delicate morsels as they
are.

They seem to thrive best in sluggish rivers with muddy beds,
and this may perhaps account for the difficulty one experiences in
keeping them alive for any great length of time in captivity. They
are not confined to rivers, however, but often inhabit the bed of
large ponds, and especially those, such as millponds, in which the
water, though apparently still, is continually being renewed.

As to keeping them alive in confinement, it seems that those
obtained from ponds are better adapted to this treatment than
those taken from the bed of streams; at least, this is my own
experience. It does not appear to be possible to rear May Flies from
their younger stages, and the larve which I have dredged from
streams have never lived long even in a large aquarium. Those
which I have kept longest were taken from a millpond, with a large
quantity of mud, and the whole placed in a large wooden tub, in
which the water was kept in almost imperceptible motion by a very
fine stream issuing from a pipe.

A large quantity of mud is an absolute necessity to the larve of

278 LIFE IN PONDS AND STREAMS

May Flies, for they live entirely on the organic matter (chiefly vece-
table) mingled with it. Like the common earthworm, they swallow
mud and all, and the nutritious materials are dissolved out by the
action of the digestive juices.

We will now notice the more interesting points in the structure
of the larva. Its body is very soft, and made up of fourteen distinct
segments. The first forms the head, the next
three the thorax, and the other ten the abdomen.

The head is provided with two long and
slender antennz, composed of many joints, and
rather thickly set with short hairs. It has also
a pair of long curved mandibles.

The next three segments each bear a pair
of legs, which are strong, flattened, and fringed

with short hair. The foremost legs are un-

0" doubtedly the chief instruments employed by

wi the larva when burrowing into the mud; and

iw N are well adapted for the purpose, being rounder
H and stronger than the others.

The appendages of the abdomen consist of
several pairs of leaflike plates, attached to the
| sides of some of the segments; and also three
Fic. 229.—Larva Jong filamentous organs, jointed, and fringed

or Ephemera, with short hairs, projecting backwards from the

EREARGED last segment. The former constitute the breath-

ing apparatus of the creature, and each one
contains a tracheal tube with a number of fine branches on each
side. It is clear, from what has already been said, that the larva
must obtain its air supply from the water, for its home is its burrow,
and this it seldom leaves; in fact the larva is so attractive to the
carnivorous inhabitants of the water, that it would be exceedingly
dangerous for it to venture out of its hole even for a moment.

Therefore the creature has no functional spiracles, as air-breath-
ing insects have, but obtains all the oxygen required for respiratory
purposes from the water, through the thin walls of the tracheal
tubes of the abdominal appendages.

The larva always burrows into the mud with its head foremost,
and the excavation is too narrow to enable the creature to turn.
At the same time, it prefers to rest at the mouth of its tube with
the head just exposed. How is this to be managed? In this way.
The larva burrows for a short distance downwards, and then works

|
|

AQUATIC INSECTS 279

itself round till its tube forms half a circle and its head is directed
upwards. Continuing in this direction, it soon reaches the surface
of the mud again, and settles down with its antenne just exposed,
and ready to devour any nutritious matter that may be drifted
towards it. At the same time, a current of water is maintained in
the burrow, for purposes of respiration, by the motion of the breath-
ing filaments, and also by an undulatory movement of the abdominal
segments.

The larve of a few species do not seem to burrow at all, but rest
more or less concealed among weeds and other submerged objects.
To these a permanent home is not so necessary, for, being covered
with a horny integument, they are not so liable to fall a prey to
other creatures ; but the soft-bodied species, on the other hand, are
so attractive to fishes that they are valued by anglers as bait.

Those in search of the latter should scrape up the bottom mud
near the banks of streams, and turn out the
contents of the dredge on a patch of bare
ground. At first no signs of life may be seen;
but if the mud be spread out till it forms a
thin layer, the larve may be seen sluggishly
wriggling out of the mire. They are helpless
creatures at such times, and, like many other
burrowing animals, are ill at ease except when
in their holes. If placed in a glass of water
they swim by an undulatory motion of the
abdomen, often assisting their progress by
movements of the legs; but supply them with
a bed of mud, and it will not be long before
they have quite disappeared beneath it.

The growth of the larva is very slow, and,
in some species at least, two years are spent
in this and the pupal stages. It is possible,
too, that this period is extended to three years
in some cases, but it is doubtful whether the
statements that have been made to this effect
have been sufficiently confirmed. s ,

The pupa is much like the larva, except : rare As: OF

. : ; : Uphemera, EN-
that the rudimentary wings are distinctly LARGED
visible in the former; and the development of
the insect is so gradual that there is no definite metamorphosis
by which we may distinguish between the larval and pupal forms.

280 LIFE IN PONDS AND STREAMS

The number of moults is large, and each one reveals the insect in a
stage of development a little in advance of that immediately pre-
ceding it; but towards the end of the creature’s aquatie life the
organs of the perfect insect develop much more rapidly.

When the pupa is ready to prepare for the short aérial existence
awaiting it, it creeps up out of the water, and rests on a stem for
the first symptoms of the coming change. The thin skin soon
becomes dry and splits, and before long the insect emerges from
its torn coat.

It is apparently a perfect insect, of a greenish colour, with large
wings, and threadlike filaments behind. The gill plates are com-
pletely cast off with the old skin, and the antenne are shorter than
before.

The insect soon begins to flutter, apparently with the object of
testing its powers of flight, and then takes its first aérial trip to a
tree or some other neighbouring object.

Here it rests again, for another change has yet to come. The
new skin dries and bursts, just as the last one did only a short time
previously. Again the insect emerges from a rent coat, leaving it
attached by the claws to the surface on which it first alighted, look-
ing just like a real insect.

The change in appearance is not quite so great as the last, but
yet considerable. The antenne are still shorter now, the tail fila-
-ments longer, and the wings more delicate. Its colour also is
lighter, and it has lost the greenish tint it had after the last moult.

After a few more preliminary flutterings, it starts off to join
its fellows in the dance over the water which we have previously
described.

Thus we see that the May Fly passes through one stage more
than those insects whose metamorphoses are described as complete.

The first winged insect is often spoken of as the ‘false imago’
(pseudimago), and is known to anglers as the ‘Green Drake.’ The
true imago, which appears a little later, is called the ‘Grey Drake,’
and both this and the false imago are used as bait.

The final transformations of May Flies usually take place in the
evening, not long before sunset, and the merry dance over the
water lasts but a few hours. During this brief period the insects
seek their mates, and the eggs are fertilised and deposited. ‘This
exhausts all their energies, there being no means of taking and
digesting food to sustain their powers.

Some of them do not appear to emerge till after sunset, and

AQUATIC INSECTS 281

before daylight the next morning nearly the whole of them will
have perished. Thus, after spending one or two years in what we
may call the preparatory stages of their existence, their short life of
maturity is passed without a chance of one glance at the sun.

Another remarkable feature concerning these insects is the
extreme regularity with which they make their appearance each
year. For a few nights in succession they appear in thousands in
their favourite haunts, and then, as if with one accord, they dis-
appear as suddenly as they came.

It is this peculiarity, together with the extremely short duration
of the winged state, and the remarkable features of the final
metamorphoses, that have claimed the attention of naturalists
for centuries. And the term Ephemera, which signifies ‘ for a day,’
denotes one of the leading characteristics of these strange insects.
The same idea is also conveyed by the popular title of ‘ Day Flies,’
which is sometimes applied to the group.

Should the reader require specimens of the perfect insects for
examination or preservation, he will find it necessary to keep a
sharp watch for them at the proper season. If he resides at a spot
rather distant from their haunts, an addressed post-card, left in the
hands of a person whose daily calling takes him where they occur,
will apprise him at the right time, and call him to witness a sight
which no entomologist can afford to lose.

There are several species of these flies, and it will be an inter-
esting work for the young naturalist to endeavour to distinguish
between them; but he must remember that the bodies of the insects
often shrivel up as they dry, till the chief features which aid in the
identification are obliterated. Hence he should preserve a portion
of his specimens in spirit or some other liquid preservative in order
to maintain the natural form of the body. But even this is not
altogether satisfactory, for all such preservatives will sooner or
later deprive the insects of more or less of their natural colour ; and
those who would wish to make a study of the differences between
the species should carefully examine the insects while alive, and
take full notes of all the features observed, illustrating them by
their own sketches if they have the ability to do so.

STONE Furies (Perlida)

Our last example of the Neuroptera is the Stone Fly (Perla), so
called from its habit of resting on stones on the banks of streams.

282 LIFE IN PONDS AND STREAMS

If you wish to see this insect you must search along the banks
of a rapid stream with a stony bed, in a wooded valley of some hilly
district, about midsummer. Examine the surfaces of stones and
rocks, either quite bare or clothed with a covering of moss or lichen ;
also the trunks of trees and the surfaces of other objects close to the
stream.

It is a very sluggish fly, of a brownish or yellowish colour, and
its large wings are folded over its body as it sits, the latter being
completely hidden by them.

The body is broad and flattened, and rather clumsily built. The
head is wide, with’ the two compound eyes at the sides, and two
long and slender jointed antenne immediately in front of them.
The organs of the mouth are not well developed, and the insect
takes no food in its winged state, which lasts only a few days.

Fic. 231.—Srone Fry (Perla marginata)

The thorax is very distinctly segmented, and the segments are
so large that, together with the head, they form quite half and
sometimes more than half the total length of the body. As a result
of this peculiarity the wings are rather widely separated at their
bases, and the second pair are situated about halfway between the
head and the tip of the abdomen.

The abdomen, which consists of ten distinct segments, is of
nearly the same width throughout, terminating very abruptly be-
hind, where it is furnished with two long jointed appendages that
are widely separated at their bases.

The wings, like those of the other Newroptera, are formed of a
thin transparent membrane that is supported by a network of
nervures. The nervures are strong and conspicuous, and present

AQUATIC INSECTS 283

none of that fineness and delicacy which characterise the wings of
Dragon Flies. In fact the neuration is coarse, the areas between the
nervures being large in proportion to the size of the wings, with
the exception of those which lie along the costal margin.

The hind wings are nearly as long as the others, and are very
much broader. When the insect is at rest they are folded longitu-
dinally beneath the front pair.

The tarsi have only three joints, the last and longest of which is
provided with a pair of short curved claws.

So sluggish are these flies that they do not fly much unless dis-
turbed, and never seem to stray far from the spot where the pupa
left the water to cast its last coat. They are often easily taken
from their resting place between the finger and thumb; and when
they take to the wing their flight is so sluggish and their course so
straight that one can easily overtake them on clear ground and
catch them in the hand.

There are several British species of the Perlid@, and some of
them are used largely as bait by anglers, to whom they are known
by various popular names. One—Nemoura variegata—is often
called the Willow Fly from its habit of settling on the trunks of
willow trees, and this species frequents sluggish muddy streams,
and even still water. Chloroperla viridis—another of the angler’s
favourites—is commonly known as Yellow Sally.

A remarkable feature of the Perlid@ is the great difference in the
size of the sexes, the male being often much less than half the size
of its mate—a fact which must be borne in mind by the beginner
who attempts to distinguish between the different species.

The females lay several hundreds of small black eggs, all held
together in one rounded mass by a membrane, and carries them
about at the tip of her abdomen for some time before depositing
them. She then drops them on the surface of the water.

The young larve hide themselves under stones and other objects
at the bottom, and here they spend the whole of their aquatic life,
apparently shunning the light, and always holding themselves in
readiness to seize any creature that comes within their reach, for
they are predaceous creatures.

They are not by any means active, and would undoubtedly
fare badly were they dependent on the captures of open chase.
They resort more to stratagem and evnning, lying in wait at the
entrance of their shelter and suddenly seizing any unwary victim
that comes within range. They attack larve of all kinds, except

284 LIFE IN PONDS AND STREAMS
the very large predaceous species, and are well armed for this
purpose with a pair of strong toothed mandibles.

They are much like the perfect insects in form, except of course
in the possession of wings. The three segments next to the head
are so large that they form about half the length of the body, and
the tip of the abdomen is provided with two long and jointed appen-
dages like those of the perfect form.

These larve may be taken in the autumn, and again in the spring ;
also during the milder days of the winter. In very cold weather
they get into more secluded quarters, where they are not so easily
found, and at this time they take no food.

They are not found among the contents of the pond net so fre-
quently as the aquatic larve previously described, on account of their
habit of hiding under stones and other objects; but they should be
searched for by turning over the stones in clear running streams,
for, when suddenly exposed by the removal of their shelter, they
are easily taken in a small short-handled net before they have an
opportunity of seeking out a new home.

If one of the larve be placed in a glass of water and closely
examined, little tufts of hairlike filaments will be seen at the bases
of the legs, and also at the bases of the abdominal appendages.
These constitute the breathing organs, and all are supplied with fine
branches of the tracheal system. .

Being placed principally at the bases of the limbs, it will be
understood that every motion of the limbs must encourage a circu-
lation of water round them, and thus assist in aérating the creature’s
blood. Also, when the insect is at rest, its body is seldom motionless
for a long time together ; but it makes a slight movement every now
and again, as if uneasy ; and there is little doubt that these motions
are for the purpose of causing the water to circulate round the
breathing organs.

The pupa is similar to the larva, but exhibits the rudiments of
the future wings. It creeps up out of the water about midsummer,
and takes up a position on a stone or trunk of a tree. Here it fixes
itself by its claws, awaiting the drying of its loosened skin.

The integument shortly splits down the back of the thorax, and
almost immediately the imago emerges, first releasing its head
and antenne from their respective cases, then the legs, and finally
the abdomen, leaving the empty skin still attached by the cases of
the claws.

In some places Stone Flies are so numerous that these empty

a oe

AQUATIC INSECTS 285

skins may be seen in abundance on objects close to the water’s edge ;
and the manner in which they are distributed seems to show that
the insects have their own favourite little nooks in the stream. In
walking along the banks of some of our small south-western rivers,
I have often seen, here and there, clusters of the skins on moss-
covered boulders, and between these clusters hardly one was to be
found.

ALDER FL.IiEs (Sialide)

Every observer of insect life must have met with these sluggish
flies. They are extremely abundant almost everywhere in the
neighbourhood of fresh water, and when at rest (and it is seldom
that they are not) they post themselves in very conspicuous and
exposed places.

They are out in early summer, at which time they may be seen
on tree trunks, rushes, palings, and in fact on almost every kind
of object within a few yards of ponds or sluggish and muddy
streams.

As they sit, the body is almost completely hidden by the
wings, which close over it, sloping on each side ¥
like the roof of a house. When disturbed, — =
they often start running, but sometimes take : ,
to the wing.- Their flight, however, is short n Fic. 232.—An

2 ae LDER FLY AT REST
and heavy, and they generaily settle within a
yard or two from their starting place, and even at times seem to
allow themselves to fall in order to avoid the trouble of flying.

If they are on rushes or other vegetation they can be easily
swept off with a net; but when they choose walls, fences, stones,
and tree trunks, they are best removed by means of a glass-
bottomed pill box.

They are altogether very dingy insects, but yet not without
interest. The head is large and clumsy, and the body is entirely
black. The antenne also are black, and of about the same length as
the body.

Like the rest of the Newroptera, the Alder Fly has four wings,
each consisting of a transparent membrane, supported by a network
of nervures. All four are large compared with the size of the body,
but the front pair are larger than the others. The former, too, are
of a smoky brown colour, and are rather awkwardly bent on the
costal margin. The hind wings are of a paler colour.

286 LIFE IN PONDS AND STREAMS

A remarkable feature of these insects is the coarseness of the
neuration of the wings. All the nervures are of a deep brown
colour, and are very thick for an insect of its size.

We have only two species of Alder Flies, and these are very
similar in size and appearance.

The larva of the Alder Fly lives in the mud of ponds and sluggish
streams. It does not construct a home like the Caddis larva, but
protects itself from its
enemies by hiding in the
mire, in which it also lies
in wait for its own prey,
for it is a carnivorous
creature, with sufficient
boldness to attack other
larve as large as itself.
Fic. 233.—Tue Auper Fry wir Wines When full grown it is

EXTENDED, TWICE NATURAL SIZE nearly an inch in length ;

and its abdomen, which

tapers off towards the end, terminates in a long pointed segment.

It has two rather short but conspicuous antenni, and its jaws are
long, curved, and sharp.

It moves about by means of its three pairs of strong legs, and
its progress is sometimes assisted by waving the abdomen from
side to side.

The breathing organs consist of slender tapering fringed appen-
dages attached to the first seven segments of the abdomen. These
contain branches of the tracheal system, into which oxygen is
absorbed from the water.

When the larva is full grown it creeps up out of the water ;
and when it has found a suitable spot it burrows into the soil, and
there hollows out an oval cell in which to undergo its changes.

It shortly casts its skin, thus exposing itself as a pupa. At this
stage its wings are distinctly visible. They are in fact quite free,
as are also the legs, except that both are enclosed in the thin skin
that is to be shed at the next moult.

When the perfect insect emerges it creeps up the surface of
some neighbouring object to dry its wings; and it never flies far
from the water in which it spent its earlier days.

The female does not go to the water to lay her eggs, but deposits
them on any object within a few yards of the water’s edge, so that

AQUATIC INSECTS 287

the young larve have to do the best they can to find their future
home.

The eggs are laid in clusters, sometimes of several hundreds.
They are cylindrical in shape, slightly pointed at the upper end,
and are neatly arranged side by side.

The young larve do not seem to be able to see the water, nor
do they seem to know their whereabouts by means of any other of
the senses. They instinctively walk downwards when they leave
the egg case, and always seem to follow the slope of a bank; but I
have observed that, if placed on the top of a ridge near the water,
a large proportion of them will walk down the wrong side, and then
go straight away from the bank.

It is possible therefore that a large number of these larvae may
perish through the apparent carelessness of the parent in deposit-
ing the eggs far from the water’s edge, and their own inability to
find their way.

Order Trichoptera (Cappis Firs)

This is a very small order of insects, including those popularly
known as Caddis Flies, the larve and pup of which live in water.

There is a great difference of opinion among naturalists as to
the true position of these insects. By some they are included with
the Newroptera, but usually they
are placed in a separate order
by themselves, and called by
the name Trichoptera, which
signifies ‘ hairy winged’ (Gr.
trichos, hair; and pteron, a
wing).

This name at once points
to one of the main distinguish-
ing features of the group, for
the wings are clothed with
small hairs. Some of the hairs
are coloured, thus producing a
distinct pattern on the wings, Fic. 234.—Tue Cappis Fry
just as the scales do on the (Phryganea minor), ENLARGED
wings of the Lepidoptera. In
fact some of the Caddis Flies look so much like certain moths,
that they are often mistaken for them by young entomologists.

288 LIFE IN PONDS AND STREAMS

Caddis Flies have four wings—membranous, and supported by
a network of nervures like those of the Newroptera ; but the hind
wings are not so long as the front pair, though often much wider.
When the insects are at rest the front wings completely cover the
others, and the latter are folded beneath the former something after
the manner of a closed fan.

The antenne are very long and composed of many joints.

As with the May Flies, the organs of the mouth of the perfect
insect are undeveloped. ‘There are no mandibles adapted for
chewing, and no food of any kind is taken by the adults.

When we examine the contents of the pond net during early
summer, we frequently find a large number of cases, of a cylindrical
or elongated conical form, constructed of various materials selected
from the vegetation or bed of the pond.

At first they exhibit no evidence of the presence of any living
inmate ; but if we allow them to remain perfectly undisturbed for
a short time, a head peeps out, followed almost immediately by
three segments bearing three pairs of legs, giving us at once the
idea of an insect form.

The creatures soon begin to move about actively, pulling their
homes along as they go, but never exposing more of their anatomy
than is necessary to allow the free movement of the limbs.

If we touch one of the insects, or pick it up by holding the case
between the finger and thumb, the protruding segments are im-
mediately retracted within the tube, which now appears quite as
devoid of life as when first we saw it.

The insects referred to are the larve of Caddis Flies; and we
gather a number of them, selecting as many different kinds of cases
as we can, and place them in boxes with scraps of pondweeds that
we may be able to observe them in confinement.

They require plenty of room in confinement, especially the
larger ones; and they should have a liberal supply of soil and
vegetation, for they are mostly vegetable feeders, either devouring
fresh green plants, or the decaying vegetable matter that is constantly
accumulating on the bed.

They climb well on the submerged vegetation ; and, considering
the size of some of the cases, and the heavy materials, such as
stones and shells, of which they are wholly or partly composed,
they seem to get along remarkably well. We must remember,
however, that objects weigh less in water than they do out of it—
that objects, when submerged, lose a weight equal to that of their

AQUATIU INSECTS 289

own volume of water, and therefore the work performed by a Caddis
larva is not so great as it appears to be.

Let us now examine the different kinds of cases made by these
larve. Here is one, small, conical, and slightly curved (fig. 235, b),
very regular in form, though not perfectly smooth, and reminding
us of the marine shell known as the ‘ elephant’s tusk.’ On exami-
nation with a lens, we find that it is composed entirely of little
grains of sand, cemented together with great regularity, and note
with surprise that the larva selected grains of a size, just as if it
were much concerned about the regular and finished appearance

Fic. 235.—Cappis CasEs

of its domicile. The case is open at both ends, as are all the others;
but the larger end only will admit of the protrusion of the inmate’s
head and limbs.

It will be interesting now to examine the case internally; but
in order to do this we must first remove the larva. It may be
supposed that this is easily accomplished by waiting till the front
seginents are exposed, and then quickly seizing the creature and
withdrawing it by a slight pull. But this will not do; for although
the larva is not attached to its case as a snail is to its shell, yet the
last segment of the abdomen is provided with a pair of hooks, the

U

290 LIFE.IN PONDS AND STREAMS

free ends of which are directed forwards, and the larva holds on so
effectually by means of these that it will often allow itself to be
torn in two rather than submit to forcible eviction.

But there is a safer, less cruel, and far more effectual way of
taking possession of the home. Take a very fine stem, or a stiff
bristle, and attack the tenant from the rear. I must admit that
this is a very inglorious procedure, but it answers our present
purpose; and the larva, not being acquainted with this form of
attack, hastily quits its tube.

We will not now concern ourselves with the peculiarities of the
larva itself, but, for the present, examine the case. On splitting it
open, we find that it is perfectly smooth within, for it is lined with
a substance that looks like a very thin and delicate paper. It is
really a silken lining, spun by the larva just in the same way as
certain caterpillars spin their cocoons. It leaves the body in a
fluid condition, and, while soft, is of a glutinous nature, so that
foreign substances are easily attached to it. It also hardens under
water, thus making the case rigid and strong.

It will of course occur to the reader that one of two alternatives
is necessarily open to the larva as its body increases in size. Hither
it must quit the case now too small to contain it, and construct
another of larger size; or it must enlarge the old one. There are a
few species that adopt the former alternative, but the majority of
them resort to the latter. They add to the larger end as occasion
requires, and even cut off the superfluous portion at the small end,
which is now too small to accommodate the terminal segments of
the abdomen.

But, it may be asked, can the larva perform the latter feat with-
out coming completely out of its home? Such a procedure would
be extremely dangerous to the insect. Caddis larvee are deemed
a luxury by fishes and a host of other carnivorous aquatics, as
anglers know well, these larve being in great request as bait; and
it would not be long before the unprotected grub would be devoured
by some hungry foe.

The answer is .this. The case, although not very spacious
within, is generally large enough to allow the insect to double and
reverse its body, and so the work may be accomplished from within,
the creature being perfectly protected as it performs its task.

It may be mentioned here that each of the different species of
Caddises constructs a case after its own peculiar style, and generally
shows a decided preference for certain materials of construction.

AQUATIC INSECTS 291

This being the case, it will naturally occur to the reader that each
species must have a preference for a particular kind of locality
where the necessary materials are to be found. Thus, the case just
described, which is constructed of particles of fine sand, is made
by a larva (Sericostoma multiguttatum) that invariably inhabits
streams the currents of which are sufficiently strong to prevent the
formation of a deposit of mud, and yet not sufficiently rapid to
carry off a fine sand. Again, there are species that inhabit rapid
currents, in which fine sand or light débris could not accumulate, and
these utilise the fragments of a stony or gravelly bed for the con-
struction of their habitation, and even sometimes attach their cases to
large stones that they themselves may withstand the force of the
stream.

But even in rapid streams there is generally a quantity of rooted
vegetation, which is cut up by the mandibles of certain Caddis larve,
and cemented together to form a case. Thus, a species called
Halesus auricollis makes its case of fragments of vegetable matter,
weighted with stones at the ‘ tail end,’ and often fixes it to a large
stone when the current is a rapid one.

It will be inferred from the above remarks that the nature of the
case remains pretty constant for each species. So much is this so,
indeed, that many species may be readily identified by a cursory
inspection of their habitations.

Some species of the family Phryganeid@ make use of pieces of
stick or stem, which they cut up into suitable lengths, and arrange
them either spirally, or in longer pieces running parallel from end
toend. Their cases are often smaller at one end than at the other
while the larva is young, but of equal size at both ends at a later
stage.

The several species of the genus Limnophilus employ a great
variety of materials. Some use sticks and stems, some cut up
dead leaves, while others use sand, small stones, and the shells of
aquatic molluses, and even, at times, the elytra of dead water beetles.

Few Caddis cases are more interesting than those formed wholly
or partially of aquatic shells; and it is astonishing how easily
quite a collection these shells can be made by the aid of the larve.
I have met with ponds where hundreds of bottom shells, such as
those of the genera Sph@rium and Pisidium, could be taken in a
few minutes by simply sweeping the Caddis larvew from the weeds,
and without the slightest occasion for disturbing the mud in which
these molluses lie. And the larvie do not confine themselves to the

u2

292 LIFE IN PONDS AND STREAMS

empty shells of dead molluscs. In fact, on some occasions the cases
are made up almost entirely of tenanted shells, the molluses having
to subsist as best they can while being dragged about from place
to place by the grub that has appropriated their shells to its own
use.

Live species of Planorbis are often captured in the same way
by Caddises, and it is often amusing to watch the procedure of the
molluses as they attempt to follow their own inclinations. The
molluse will make an attempt to crawl away at a time when the
larva is at rest, but it is not strong enough to move the heavy case ;
and just when the snail has succeeded in getting a foothold, and
attempts to go its own way, the larva decides on an opposite course,
and the poor snail is torn away from the object to which it had
attached itself.

In addition to the shells already named, the smaller Limnea,
the freshwater limpets (Ancylus), and species of Bithynia and
Valvata are all appropriated by Caddis larve for their cases.

The shells selected are almost invariably fixed with their flattest
side turned inwards, and the same applies to the stones and other
objects used in the construction of the cases.

Among the other materials employed for this purpose may
be mentioned pieces of reeds and rushes, cut into suitable lengths ;
the seeds of rushes and other plants; and also dead leaves. The
last named are sometimes cut up into small pieces and arranged
spirally, or in longer pieces placed side by side, or are even used
entire.

Some species are also more or less social in their habits, two or
more larve living in a common home attached to a stone in the
bed of a stream. Such homes are sometimes constructed of vege-
table matter or other débris, or they may consist of little or nothing
save the silken secretion from the glands of the larve.

Now let us examine the larve themselves. For this purpose we
select one of the larger species, and drive it from its case by gently
probing it from behind with a grass stem as before described.

One of the first features that strike us is the remarkable differ-
ence between the front and hind segments. The head and the
thorax, which are the only parts that protrude from the case when
the animal is walking, are protected by a hardened integument ;
but the segments of the abdomen, that are always protected by the
case, are lighter in colour and very soft, and we can quite conceive
that these grubs would be dainty luxuries for fishes.

——

AQUATIC INSECTS 293

The mouth is provided with a pair of mandibles, and just behind
it, on the under side of the head, is the spinneret that communi-
cates with the gland from which a viscid fluid is secreted.

The legs are strong, and are covered with the same hardened
horny integument that protects the three segments to which they
are attached.

The first segment of the abdomen has usually no appendages,
but several of the following segments bear filamentous organs which

lie closely on the back when the larva ~
is out of the water, but float off and ‘ L
assume a feathery appearance when it NN in) Va
is submerged. = a a>
Each of the filaments is supplied ; we, i mN
with a branch of the tracheal system fi he aie
of the insect, and is really a kind of iw A
gill, through the very thin walls of AA
which oxygen gas passes from the ri
water. 1, SIF
It may be supposed that the crea- 7)
ture, being normally confined rather ASAD
closely in a narrow tube, would have ASA
only a limited supply of air passing gi
over and around its breathing organs ; :
but this is not the case. We have ‘oh
already seen that the case is generally Dy >

of such a diameter that the larva can
double its body within it, also that it
is usually open at both ends.

Now, the larva causes a4 current of water to flow through the
tube by gently undulating its abdomen. This motion is not inces-
sant, but carried on at frequent intervals; and by this means the
breathing filaments are bathed in a slow stream of fresh water.

But, then, how are these movements to be observed, seeing that
the Caddis cases are usually quite opaque ?

In the first place it may be noticed that a larva, deprived of its
home and placed in a glass of water, will frequently wave its abdo-

Fic. 236.—A Cappis
LARVA, ENLARGED

_men in the manner described, even though there may he no necessity

for it under the circumstances. But this is not all, for it is possible
to compel the creature to use transparent substances for the con-
struction of the case, so that the motions of its body may be
witnessed under more natural conditions.

294 LIFE IN PONDS AND STREAMS

Turn a larva out of its tube, and place it in a vessel of water
containing no solid substances except what you have yourself intro-
duced for building material, and it will soon commence constructing
a tube of them.

Many very interesting results may thus be obtained, though I
must say that I have not found all species equally ready to build
under circumstances so unnatural to them. The commoner species
of Phryganea which inhabit ponds and ditches almost everywhere,
and some of the sand-builders cf our ponds and rivers are very
willing workers under such conditions, and in the course of a few
hours will construct cases of almost anything with which they are
provided.

If our object is to obtain amusement only, very pretty and
striking results may be produced by supplying the larve with sands
or small glass beads of different colours; and if they are transferred
from one vessel to another during the operation, they may be made
to complete their cases with substances of a different nature from
those with which they started. But to return to the transparent
cases to which we have above referred. These I have obtained as
follows:

The larve, after removal from their cases, are placed in a vessel
of clean water without any sediment. They are then provided with
very thin plates of glass, such as may be easily obtained by heating
the end of a piece of glass tubing in a blowpipe flame, blowing out
a thin bulb, and then breaking it into little pieces of about an eighth
of an inch or more in length. The pieces should not be too small,
or the case produced will be too opaque to allow a clear view of the
larve within. In fact, the larger they are the better, providing they
are not too cumbersome for the insects to manipulate.

With cases produced in this way the larvee may be watched with
ease, and the undulations of the abdomen by means of which the
water currents are. maintained for breathing purposes rendered
visible.

The method of ‘ spinning up’ the case is also very instructive,
and with close observation in a clear vessel, we can even distinguish
the silken thread as it is worked from piece to piece while the case
is being built up.

Some Caddis larvee do not construct any case at all, but find a
hiding place ready provided in the water. I have often found large
larve within the hollow of a piece of stem which has simply been
cut to a length adapted to that of the inmate.

AQUATIC INSECTS 295

In such instances it is necessary for the insects to quit their old
dwellings when too small for their needs, and seek another of
suitable size. .

It is remarkable how unerringly a larva will often find its own
case after having been expelled, even when placed in the midst
of several similar cases, all of which are empty. To test this I
have driven half a dozen larve from their tubes—all hollow stems
of similar appearance and size; and, after marking one of them
and isolating the larva that inhabited it, have put all the cases into
one bottle, together with the larva in question. In nearly every
instance the creature would search out its own home, instead of
occupying the one nearest at hand, which would apparently have
served its purpose quite as well.

A larva always re-enters its case head first, and if the case is
equally large and also open at both ends it has no need to turn itself
round after itisin. But many cases are much smaller at one end
than at the other, and the larve which have been expelled from
these will turn themselves round after entering, in order to bring
their heads to the larger aperture.

Caddis larve are hatched from the eggs during the summer
months, and are not full grown when the cold weather of winter
sets in. But they are far less active during the latter period, and
spend most of their time under the shelter of stones or in the mud
or other sediment of the water in which they live. It is probable,
too, that they partake of very little food during this period of in-
activity.

We have spoken of these larve as vegetable feeders, but some
few species seem to show a preference for an animal diet ; and it is
probable that some of them are entirely carnivorous.

These insects are often called Caddis Worms by the anglers who
use them as bait, but it would hardly be necessary here to point out
that they are quite distinct from worms—that there is none but a
very distant relationship between the true worms and insects, the
latter being distinguished from the former by their metamorphoses
and by the presence of three pairs of walking legs.

When the winter is over, the Caddis larve resume activity, and
grow rapidly till their full size is reached in late spring or early
summer. They then cease to feed, and start making preparations
for the changes they have to undergo.

At this period they secure themselves from the attack of their
numerous enemies by sealing up the ends of their cases, But one

296 LIFE IN PONDS AND STREAMS

end at least of the case must be in free communication with the
water, since oxygen is necessary still for respiratory purposes.

Some species cover the ends of their cases with a silken network,
while others partially seal them up by spinning together some

pieces of the same materials

/ that were used to construct the

/ case itself. Some partially bury

their cases in mud, leaving the

front portion exposed for securing
water and air.

A few days after this work
has been completed, the larva
casts its skin, thus revealing
itself as a pupa, which may be
readily recognised by its peculiar
mummy-like form. The legs
are now folded under the body,
and the wings and other organs
which mark the perfect state are

Fic. 237.—Cappis Fry (Limno- all more or less visible.
philus bicolor), ENLARGED Two or three weeks are now
spent in a perfectly quiescent
state ; and when the time arrives for the final change, the insect again
becomes active, breaks loose from the case that has protected it for
so many months, and seeks out a convenient spot from which it
can climb out of the water, sometimes even swimming by the aid
of its legs, which, like the rest of the body, are now covered with the
loosened skin that is soon to be cast off.

This isa time of great danger to the Caddis. All the carnivorous
aquatic animals that spent the winter ina dormant or semi-dormant
condition have now been called into activity by the genial sun, and
their keen appetites keep them always on the alert for tender grubs
of all kinds; and it is probable that a large proportion of the Caddis
pup are seized by these hungry foes as they make their short
journey from the deserted case to the surface of the water.

It is possible, too, that the danger is greater to the females than
the males, for their bulky bodies, already full of eggs, must certainly
give greater satisfaction to the hungry carnivores than the slender
and comparatively empty bodies of the males.

The majority of species climb quite out of the water, and rest on
the stem of a plant or on some other object to await the drying of

Se"

eaceeue :

=

]

-———— | a
|
j

AQUATIC INSECTS 297

the loose skin. This does not occupy much time, and the skin then
splits, allowing the perfect insect to emerge. Then follows the ex-
pansion and subsequent drying of the hairy wings, after which the
fully developed Caddis Fly, now a free child of the air, starts on its
short life of sport and parental duties.

It has been observed that the pup# of some species do not leave
the water in order to pass through their final metamorphosis, but
simply allow themselves to float on the surface, and, having emerged

Fic. 238.—Cappis Fry (Leptoceros ochraceus), SLIGHTLY ENLARGED

from the pupal skin, make use of this as a kind of raft on which
to expose the wings to sun and air. This habit is common with
enats, and will be referred to again when we deal with those in-
sects.

The female, after discharging her eggs, carries them about with
her for a time. They are all in one mass, and surrounded by a
covering of glutinous matter. She deposits them in water, some-
times walking down a submerged stem to accomplish her end.

As soon as the young larvie are hatched they commence the
work of tube-building. They are very active at first, and some
species even swim with considerable dexterity at this stage, using

298 LIFE IN PONDS AND STREAMS

their fringed hind legs something after the manner of a water
beetle.

There are a good many species of Caddis Flies, a few of which
are figured.

The illustrations given, together with the general features of
the order, will be sufficient to enable the reader to know a Caddis
when he sees one.

The Great Caddis Fly (Phryganea grandis), shown in fig. 212,
is one of an extensive genus. The others are illustrations of smaller
species. The latter are slightly enlarged, but the natural size of the
insects is shown.

AquaTic DIPTERA

The Diptera, or two-winged insects, include several species whose
earlier stages are spent in water, and of which the perfect forms are
to be found hovering over water or flying in the neighbourhood of
ponds and ditches.

The hind wings of dipterous insects always exist in a very rudi-
mental condition, being represented by mere scales, or by a pair of
delicate filaments which terminate in a knob resembling the head
of a pin. The latter are often termed halteres, balancers, or poisers,
which names have arisen from the supposition that the organs in
question assist in steadying the insect while on the wing; but it is
difficult to conceive how such a function could be performed by
organs so small and so short compared with the body and its larger
appendages.

The functional wings are attached to the middle segment of the
thorax, and therefore correspond with the front pair of four-winged
insects. They are membranous, and usually clear and transparent,
but often marked with coloured spots or patches; and the mem-
brane is supported by a few nervures.

The mouth is suctorial, and constructed on the same plan as
that of the Hemiptera, the labium being prolonged into a tube
through which the insect sucks up the juices on which it feeds.

In the Diptera the metamorphoses are complete and well marked,
and the pupa is generally quiescent, but sometimes it is as active as
the larva. The larva is a footless grub, in many cases commonly
known as a maggot. The segments are usually well marked, but
often there is no distinct head.

Although we are directly concerned only with those species
which are of aquatic habits, yet I would recommend those readers

AQUATIC INSEUTS 299

who are not acquainted with the general characters of the Diptera
to examine the common Blow Fly,and watch it through its different
stages. This well-known insect is easily obtained throughout the
whole of the summer, and the rearing of it is a matter which pre-
sents not the slightest difficulty. Simply expose a small piece of
meat of any kind to the air, placing it on a bed of wet sand. Ina
short time the clusters of eggs may be observed, and soon the young
larvee will commence their ravages on the store of food provided for
them. The pup, which in this case are quiescent and encased
in a brownish covering, may be afterwards dug out of the sand into
which the larve burrow when fully fed; and the emergence of the
perfect insect may be watched, providing the observer happens to be
on the alert at the right time.
We will now deal with some of our aquatic Diptera.

THE Gnat (Culex) AnD ALLIED INSECTS

One of the most interesting of the aquatic Diptera is the
Common Gnat (Culex pipiens), the merry flight of which is well
known to everybody. There are many, however, to whom the
familiar name recalls something more than a lively movement in
the still summer air. It suggests sensations which leave a more
lasting impression —a gentle buzzing sound in the neighbourhood of
one’s ears, followed by a sharp stinging sensation on some tender
unprotected spot.

But the insect is as interesting as it is troublesome; more so,
indeed ; and one forgets the tantalising ‘ bite ’ of the creature when
its exquisite beauty is displayed beneath the lens.

The wings are long and narrow, and the nervures are clothed
with minute scales, something like those which cover the wings of
most of the Lepidoptera. These scales are marked with ridges,
which project beyond the edge, giving a spiny appearance; and
they are not restricted to the nervures of the wings, but also clothe
the body and the limbs. Like those of the Lepidoptera, they are
easily removed by means of a soft brush, and may then be trans-
ferred to a glass slip for examination under the microscope.

The body itself is somewhat club-shaped, and the legs are very
long and slender.

It is the head of the Gnat that demands our greatest attention,
however ; and more especially the wonderful arrangement of organs
that form the weapon of offence. But it must be observed that the

300 LIFE IN PONDS AND STREAMS:

female only is capable of inflicting pain, and the following remarks '
apply to her alone.

, Z
LS oo SS

OO

Fia. 239.—Tur Gnrar—Larva, Pura, Perrecr Insecr EMERGING, AND
THE MALE AND» FEMALE FLYING

- AQUATIC INSECTS 301

The labrum, or upper lip, is prolonged into a stiff bristle-like tube,
slit throughout its length behind, and used for suction. The lower
lip (labium) is a long fale flexible sheath, grooved in front to accom-
modate the Gain and maxille. The former
are two long and slender lancets for piercing, very
sharp and barbed at the tip. The latter also con-
stitute a pair of slender lancets, equally sharp, but
instead of being barbed they are provided with a
sawlike edge at the tip.

In addition to these four piercing organs there
is a fifth lancet, sometimes called the tongue, but
_ which is really a prolongation of the middle portion
of the labrum. Thus the female gnat is provided

with five separate lancets, guided and protected iy eile E
: ScALE OF THE
by the labrum above and the labium below. She Guat

thrusts them into the flesh of her victims, and then
sucks the blood from the small wound thus made.

The method of suction is interesting. The csophagus has the
power of enlargement, thus serving
the purpose of an exhausting pump.
When it expands, it decreases the
pressure in the digestive tube behind
the mouth, thus encouraging the flow
of fiuid into the mouth from without.

As with some of the water bugs
(Notonecta and Naucoris), the pain
produced by the ‘ bite ’ is so sharp that
it is difficult to believe that it is pro-
duced by mechanical irritation only,
without the injection of an irritant
poison. Yet this is probably the case,
for as yet no poison gland seems to
have been traced. It is probable that the
intensity of pain is due to the action
of the barbed point of the mandibles,
and of the sawlike edges of the maxille.

: — comme eres enero on Fic. 241.—OrGANS OF THE
flicting pain, the parts of the mouth, Mourn oF ta Wauice
so highly organised in the female, GNAT, ENLARGED
being undeveloped in this sex. And
it is difficult to understand why the female herself should be

302 LIFE IN PONDS AND STREAMS

thus armed ; for not only does it appear probable that only a very
small proportion of the myriads of gnats which swarm in the air
ever pierce the skin of an animal, but gnats also abound in desolate
subarctic regions where hardly an animal is to be seen. Still we
are well aware that the female gnat can ‘ bite,’ and sometimes does
do so; and it is also possible that her mouth organs are used for
extracting the juices from vegetables as well as from plants.

We must not omit to notice, however, the beautiful form of the
antenne of the male. These organs are composed of fourteen
separate joints, each one of which has a radiating cluster of long and
thin hairs, so that the whole looks like a very delicate feather. The
female also has a pair of antenne, but the tufts of hairs are so short
that the organs are comparatively inconspicuous.

The female gnat lays her eggs on the surface of the water, and it
is very interesting to watch the operation, as well as that of glueing
the eggs together.

She usually alights on the surface of the water, and immediately
crosses her hind legs, and supports herself on the other four. Her
weight is not sufficient to cause the feet to break through the surface
film, and, if the water is perfectly calm, four little depressions may
be observed where the feet rest on the water.

It generally happens that the gnat has to make many movements
before quite satisfied as to the suitability of a spot for her purpose,
and so she may be seen walking on the surface of the water or on
Hoating weeds in search of a favourable locality. Her movements
on the water itself are very awkward, compared with those of the
water gnats and pond skaters, for she proceeds by a series of
laboured jerks, generally using her wings as well as the two pairs of
legs.

The spot usually chosen is either near to a floating weed or other
object, or else close to the margin of the pond. She is thus enabled
to support the front pair of legs on a solid substance, and sometimes
the second pair also; but the latter often have no other support than
the water itself.

The hind legs remain crossed and free in the air, and serve to
guide the eggs into the required positions.

The eggs are cylindrical in form, but taper off at one end, and
are provided with a lid at the other ; and each one is covered with
a sticky substance which soon dries on exposure to air. These are
all arranged side by side with wonderful regularity, the similar ends
being placed together; and the whole cluster, numbering from two

AQUATIC INSECTS 303

hundred to three hundred, is built up into a little boat or raft, with
the pointed ends at the upper, concave side, and the lids forming the
convex surface below. The raft thus formed is only about three-
sixteenths of an inch in diameter, and is left
floating on the surface of the water.

It is in itself such an interesting object
that we strongly recommend the young pond ;
naturalist to procure one for examination and Fic. 242.—Tur Eee
experiment ; and there is no reason, too, why ance oT. Guat,
he should not watch the process of building.

For this purpose there is no necessity to travel away from home.
Simply place a tub of water in a sheltered corner of the garden,
throw into it some duckweed or other aquatic vegetation, and let it
remain undisturbed.

It will not be long before the gnats will find the accommodation
thus provided, and a little patient observation will now be well
rewarded. It should be remembered, however, that these insects
usually deposit their eggs early in the day, before the sun is very
high ; though in dull weather I have often seen them thus engaged
up to midday.

It will be noticed that the peculiar nature of the egg raft provides
for a free exposure of the eggs to the atmosphere—a condition pro-
bably absolutely necessary for the development of the young larve,
and also allows the newly hatched insects to pass directly from the
egg cases into the water that forms their home.

It is wonderful, too, how constantly these conditions are main-
tained in defiance of the natural forces which tend to disturb them.
To prove this, blow a current of air on the surface of the water on
which an egg raft tloats—disturb the water as you will, and the raft
maintains its position ; or, if so roughly used that it is overturned,
it rights itself again like a lifeboat.

Again, push the raft under water, and still the conditions are
practically the same, for the water, instead of penetrating into the
spaces between the upper pointed ends of the eggs, leaves a film of
air over the whole surface, shining like a layer of quicksilver.
Then release the raft, and immediately it rises to the surface, rights
itself if in the wrong position, and the bubble that covered the
upper surface then bursts, leaving that surface perfectly drv and
free.

Let us now examine the larva of the gnat ; and for this purpose
we procure a few larve from a stagnant pool or ditch, or a waterbutt,

504 LIFE IN PONDS AND STREAMS

and place them in a bottle of clear water. They are limbless
creatures that move about in the water by wriggling their slender
bodies.

When at rest they are suspended, head downwards, from the
surface film of the water,in which position the breathing apparatus
is exposed to the free air, while, at the same time, the head is
directed downwards in search of food. The head is provided with
hairlike filaments, by the movements of which currents of water
are made to carry particles of food towards the mouth.

The segments of the abdomen are all distinct, and at the eighth
one the body is bent. At the same point a cylindrical tube branches
off from the abdomen in such a manner as to give the end of the
body a bifid appearance.

The tube to which we refer is connected with the tracheal
system of the insect. It contains two air tubes, continuous with
the two main tracheal trunks that run through the body; and when
the larva is at rest, the extremity of this tube is open to the air, just
at the surface of the water.

If you rap the table on which the bottle containing the larve
rests, the larvee will detach themselves from the surface film, and
allow themselves to sink, thus showing that they are heavier than
the water.

And now we have to solve the problem of the creature’s
suspension—to find out how a larva whose body is heavier than its
own weight of water can suspend itself at the surface without
attachment to any solid object.

A close examination of the surface of the water where one of
the larve is suspended will show that the surface film of the water
is actually pulled down a little way by the weight of the insect.
We may also observe five little valves at the orifice of the breathing
tube. These are not easily wetted by water; so that while the
larva is thus suspended from the film all round the exterior of
the valves, the orifice between communicates freely with the
atmosphere.

When the larva wishes to descend, it closes the opening of the
tube by bringing the five valves together, thus releasing itself from
the pull of the film, and then its body sinks in virtue of its superior
specific gravity.

It never remains below for any length of time together ; but, as
soon as the disturbance that drove it to the bottom ceases, it rises
by wriggling its body, keeping the valves of its breathing tube close

AQUATIC INSECTS 305

together all the time. When it reaches the surface it thrusts the
valves through the film and opens them ; it then remains perfectly
stationary, allowing its body to sink and hang by the film, the con-
tractile power of which pulls the valves upward and outward on all
sides.

The larva of the gnat is so transparent that it becomes a very
interesting object when viewed through a lens or under the lowest
power of a compound microscope. The distribution of the tracheal
tubes can be easily made out, not only the main trunks, but also
the finer divisions which ramify into the different segments of the
body. The digestive tube is rendered particularly conspicuous by
its dark and opaque contents, and the contractile vessel that serves
the purpose of a heart is also distinctly visible.

The larva undergoes several moults during its growth, and the
last one reveals it in the form of a pupa. But how the creature has
changed! The organs of the future fly, some of which were to be
seen even in the transparent larva, are now well developed, though
as yet encased. The head with the antenne and mouth organs,
and the legs and wings of the future fly, all together form a great
rounded mass, from which the comparatively narrow abdomen
extends ; and each of the appendages is ensheathed in its own ease.
The pupa is also provided with a pair of leaflike swimming organs
at the tip of the abdomen.

But the most remarkable change is perhaps that which has
taken place in the respiratory system. The tracheal system no
longer opens at the eighth segment, but by means of two curved
tubes on the back of the thorax. Hence we find the pupa sus-
pended at the surface in a position very different from that assumed
during the larval stage. The insect, though not now quiescent,
no longer requires any food, and hence there is no longer any
necessity for it to have its head directed downward in the water.
Again, the insect is shortly to assume its winged state, and we
may therefore reasonably expect to find it resting in a position
that will allow it to emerge direct from the pupal skin into the air.
This is really the case, for its position is such that the back of the
thorax—the part where the skin splits—is close to the surface and
directed upward.

In this position, too, the mouths of the two thoracic breathing
tubes are flush with the surface of the water, and the water is no
longer kept out by the action of five valves, as during the larval

x

306 LIFE IN PONDS AND STREAMS

stage, but by means of a number of very fine hairs, between which
the water cannot penetrate.

When the time is ripe for the final metamorphosis, the skin
splits, and the insect soon extricates its head and thorax through
the opening. The legs, wings, and other appendages are all with-
drawn from their respective cases, and finally the abdomen becomes
free.

The newly emerged gnat now requires a foothold until the wings
are sufficiently dry and rigid for the first flight. This is provided
by the old pupal skin, which, being empty and very light, serves
the purpose of a raft ; and on this the gnat rests for a short time,
while the drying is in progress.

The term ‘ gnat’ is often applied, or rather misappled, to certain
insects of another genus, called Chironomus, and popularly known
as Midges. These belong to the family Tapulid@, which includes
the well-known ‘ Daddy-long-legs.’

They may be seen flying about in clusters in our gardens,
| especially in the neigh-
bourhood of ponds,
ditches, muddy streams,
and rainwater butts, such
being the natural homes
of their larve; and they
frequently stray into our
houses.

Chironomus so closely
resembles the gnat in
general appearance, that
there is some little excuse
for the mistake above
referred to, but yet there
are some important differ-
ences to be detected on a
close examination. The
female has no piercing
and sucking organ like
that of the female gnat ;
in fact it takes no food
of any kind. Also, there
are no scales on the nervures of the wings of Chironomus ; and
the insect rests on its second and third pairs of legs, keeping the

Fic. 243.—Chironomus, ENLARGED

AQUATIC INSECTS 307

first pair raised, and crossed one over the other. The male may
be distinguished from the female by its feathered antenne.

The eggs of Chironomus are laid on the surface of water, and,
like those of the gnat, seem to require exposure to air. As they
are often deposited on running water, itis essential that they should
be fixed in some way or another, so that they may not be carried
away by the current; hence we find them attached to floating
objects, or to fixed objects just at the surface level. They are laid
in chains, varying from a quarter of an inch to nearly an inch in
length, or in round or oval masses, according to the species. They
are covered with a glutinous substance, like those of caddis flies ;
but in the case of Chironomus this substance swells out consider-
ably by the absorption of water, forming a jelly-like protective
covering. This substance, too, is so clear
and transparent that the development of the
young larve may be watched with the
greatest of ease.

The larve are wormlike creatures, about
three-quarters of an inch in length when
fully grown, and of a bright scarlet colour.
They are used largely as bait by anglers, to
whom they are known by the name of Blood-
worms.

They must be familiar objects to all who
have any acquaintance with the open water-
butt or who have ever dredged a little mud
from a stagnant pool or ditch. They live in
burrows which they excavate in soft mud, or
in the spaces between the decaying leaves
that so often cover the bed of standing or ase
slow-running water. In either case the Aas
particles of the substance surrounding them
are held together by means of a silky secre-

Fic. 244.—A ‘ Bioop-

s c WORM,’ VIEWED
tion from the salivary glands. FROM ABOVE, EN-
The burrows are always open at both LARGED

ends, and thus the larve are enabled to feed

on any suitable substance that comes within their reach while
their soft bodies are almost entirely concealed. At the same
time they set up water currents through the tubes for respiratory
purposes by undulatory movements of their bodies, as do the

larvee of caddis flies,
x

308 LIFE IN PONDS AND STREAMS

It will be noted, however, that while the caddis larva generally
lives in a portable case, the ‘bloodworm’ lives in a fixed home,
and therefore cannot travel in search of food without exposing
itself. It is probable, too, that the ‘ bloodworm ’ is often compelled
to leave its home in order to obtain sufficient air for its respiration,
since it generally inhabits the mud of very stagnant water, in which
much carbonic acid gas must necessarily be produced by the de-
composition of vegetable matter. This will probably account for
the fact that the larva often leaves its burrow and swims about
freely in-the water nearer to the surface. And, having no appen-
dages adapted for swimming, it progresses by vigorously looping its
body, first on one side and then on the other.

Although the colour of the larva is so deep, yet the body is so
transparent that its internal organs are plainly revealed by trans-
mitted light with the aid of a low magnifying power. Its air tubes
are not nearly so apparent as in the case of the larva of the gnat;
in fact the tracheal system is only slightly developed, and the
‘bloodworm’ probably obtains most of the air required for the
aération of its crimson blood by direct absorption through the soft
structures of its body. The dorsal heart, however, may be seen
pulsating most distinctly. It must be mentioned, by the way, that
the larvee of some species of Chironomus have colourless blood, and
therefore colourless bodies.

The ‘ bloodworm’ has a pair of short legs attached to the first
segment of the thorax, and these are adapted for prehension, being
provided with a circle of little hooks. Like the caddis larva, it
has also hooked appendages at the extremity of the abdomen, by
which it can hold on to the silken lining ofits burrow. On the last
segment but one it has four tubular appendages, probably connected
with the respiratory function.

The food consists of decaying organic matter, which is seized
and bitten by a pair of powerful mandibles. The head has also a
pair of jointed antenne.

The pupa of Chironomus is very much like that of the gnat, the
head and thorax, together with their appendages, forming one large
younded mass; but instead of the trumpet-like breathing tubes, it
is provided with tufts of hairlike filaments that communicate with
the trachee, now more highly developed.

The final metamorphoses very closely resemble those of the
last genus, and therefore need not be detailed here.

We have several gnatlike insects with aquatic larve, but the

AQUATIC INSECTS 309

exigencies of space will not allow anything more than a brief
description of one other.

It often occurs that we find abundance of life in the aquarium
into which we have thrown the miscellaneous haulings of a day’s
pond work—life which was not seen at all during the cursory
examination in the field, either on account of the minuteness of
the creatures concerned, or because of the extreme delicacy and
transparency of their bodies.

Among these we often find the larva of a little tly belonging to
the genus Corethra, which was taken from among the weeds or
partially submerged grass of a stagnant pool or ditch.

So transparent is this larva that it may often be overlooked even
in the aquarium, and the startling suddenness with which it disap-
pears or makes its appearance has earned for it the popular name
of the ‘ phantom larva.’

Ifit is required to examine its general characters and movements,
it should be removed from the aquarium by means of the dipping
tube, and then transferred to a small, shallow glass vessel, so that
it may be easily inspected from above by the aid of a lens.

For a short time it remains perfectly motionless and suspended
horizontally in the water, but just as we are beginning to make
out some of the details of its structure it suddenly darts away with
such speed that the movement cannot be closely observed. How-
ever, we discern it again, about three-quarters of an inch from its
former position, and just as motionless as when we first commenced
our observation.

A careful examination shows that these movements are produced
by a very sudden bending of the body, unaided by appendages of
any kind save a finlike organ composed of a number of plumed
bristles placed vertically beneath the hinder portion of the abdo-
men.

The larva has no limbs, and the body is so clear and trans-
parent that the internal organs may be seen distinctly by transmitted
light.

The most striking feature at first sight is the presence of two
pairs of conspicuous black spots, one pair in the segment next the
head, and the other in the eighth. These are really air cavities,
and seem to serve a double purpose. Being connected with the
two tracheal trunks, they have undoubtedly something to do with
respiration ; but they also serve the purpose of a couple of floats to
assist in maintaining a horizontal position in the water.

310 LIFE IN PONDS AND STREAMS

The larva has no spiracles, and no external organ like the gills
of some aquatic insects, but seems to obtain the air it requires
direct from the water through the soft structures of the body.

In addition to these air cavities one may see the digestive tube,
the pulsating tubular heart, and the chain of nerve ganglia, all
visible through the clear body.

The larva is a predaceous creature, feeding on various small
insects and crustaceans, which are seized by its prehensile antenne,
and afterwards manipulated by a pair of handlike jaws.

Fic. 245.—Larva Fic. 246.—Tue Prerrectr Corethra
or Corethra

The pupa is much like that of the gnat, save that the rounded
mass formed by the head and thorax is not so large in proportion
to the size of the body, and, like the pupa of the gnat, it possesses
a pair of breathing tubes which stand out from the thorax, and it
rests at the surface of the water in a vertical position, awaiting its
final change.

It has a broad and flattened tail, which reminds one of the
telson of the crayfish. It is also used in a similar manner, for
when the pupa is alarmed it suddenly bends its body, raising the
tail and thus causing itself to descend by a series of jerks, of course
travelling tail foremost.

AQUATIC INSECTS 311

The perfect insect is much like the two preceding, and may be
easily mistaken for a gnat. It has many-jointed antenne, which
are fully plumed in the male sex.

OrHER AQuatTic DIpreRa

We have now to deal with a few diptercus insects that are of a
very different build from the preceding. Their bodies are stout,
and the antenne very much shorter in proportion, and they resemble
bees and ‘ bluebottles’ more than gnats. They are also strong on
the wing, and often exhibit very brilliant colours.

Our first example is the Common
Chameleon Fly, of the genus Stratiomys.
Its body is broad and rather flat. The
ground colour is black, relieved by bright
yellow markings, and the antenne are
composed of only three segments.

This fly is somewhat beelike, and may Fic, 247._Stra-
often be found sucking the sweet juices tiomys chameleon
of flowers in the neighbourhood of ponds.

Its flight is rapid, but not long, and it may be easily followed up
from one resting place to another.

It does not lay its eggs on the surface of the water, after the
manner of the species previously described, but deposits them on
the leaves of semi-aquatic plants that stand up above the surface.

The larva is a very strange creature. It is a flattened and
legless maggot, thicker in the middle, and tapering off towards both
the head and the tail, the latter end being very long and slender.
The segments of the fore extremity are short, but they increase
uniformly in length towards the tail.

The length of the larva may vary from one to two and a half
inches, according to the creature’s own desire, for the segments of
the body are capable of a telescopic motion, the front segments
retreating each within the one behind it, and each of the others
into the one in front of it. Thus when the larva is alarmed both
extremities- approach one another, causing the body to become
shorter and thicker.

The colour of this larva is very variable, but is generally some
shade of green, yellow, or brown—colours which tone well with the
surroundings, and consequently are more or less protective. Its
skin is tough and leathery.

512 LIFE IN PONDS AND STREAMS

It inhabits stagnant pools and ditches, sometimes creeping in
the mud, dragging its body along by means of its mouth, probably
assisted to some extent by the short bristles which project backwards
from each of the segments. It
also swims at times by alternately
doubling and extending its flexible
body, but its progress is rather
slow. Usually, however, it rests at
the surface, suspended from the
film by the tail in a manner to be
described presently, and keeping up
a circulation of the water by means

_ of the short appendages of the head
for the purpose of securing the
small aquatic creatures that form
its food.

The tip of the tail is furnished
with from twenty-five to thirty
radiating feathered bristles, which
can be spread out or brought closer
at will. As long as the larva is
swimming, or crawling in the mud

Fic. 248.—Larva OF at the bottom, all the tail filaments

Stratiomys are held together in such a manner

as to form a little cup, which always

encloses a bubble of air for respiration while the creature remains
submerged.

When it rises to the top for repose, it thrusts the top of the
cup through the surface film, and immediately spreads out the
bristles into the shape of a shallow cone. The bubble previously
enclosed thus escapes, and the cavity is in free communication with
the atmosphere; and since the filaments are not readily wetted
by water, they are pulled upwards and outwards by the elastic
film, thus enabling the larva, which is heavier than its own weight
of water, to suspend itself head downwards.

It will be surmised from the above description that the larva
of Stratiomys has its tracheal system communicating with the
air enclosed by the filaments of the tail. It has spiracles along the
sides of the body, but these are not functional.

This insect does not pupate in the water, but burrows into the

“—= =

AQUATIC INSECTS 513

soil near the water for this purpose. The larval skin then becomes
loosened on all sides; but instead of being thrown completely
away at the tail, as is the case with m st insects under the same
conditions, it remains intact, even to the filaments of the tail, and
so forms a loose protecting covering over the pupa.

As a rule the pupa of an insect is smaller than the full-grown
larva; but in the case of Stratiomys the difference is very great,
so that the pupa, which is quiescent, lies in a case which is not
half filled by the occupant.

The pupal condition lasts only for a few days, at the end of
which time the perfect insect breaks through both its pupal and
larval coats and finds its way into the air.

Another insect (S. furcata) of the same species is figured here.
It is very similar to S. chameleon in colouring, and its life history is
also much the same.

Fie. 249,—Stratiomys Fie. 250.—Eristalis tenaz,
furcata SLIGHTLY ENLARGED

Our last example of the diptera is the Drone Fly (Fristalis
tenax), the remarkable aquatic larva of which is commonly known
as the Rat-tailed Maggot.

To find this larva you must search in the smallest, muddiest,
and most putrid waters, the black mud of which consists largely of
decomposing organic matter. The net must be made to scrape up
the mud close to the banks, where the water is not more than two
or three inches in depth.

It is not very convenient to observe the habits of this larva in
its native haunts, both on account of the nature of its home and
because of its habit of burrowing into the mud; but if the dredgings
of the pond, mud and all, be transferred to a shallow dish or tub
kept in the garden and covered with an inch or two of water,

514 LIFE IN PONDS AND STREAMS

the water, black and thick at first, will soon deposit its sediment,
becoming sufficiently clear to enable one to watch the movements
of the insects.

At first they seem to be unsettled and restless, swimming
about clumsily in the muddy water, or creeping about on the
bottom or sides of the vessel. But after a time,
when the water is clear, we see them partially
buried in the odorous mud, with their long and
slender ‘rat tails’ standing up perpendicularly
and just touching the surface.

Now tap the vessel that holds them, and
immediately all the tails disappear, but only to
be thrust out again as soon as the alarm is over.
All the time the cylindrical bodies are buried
deeply in the putrid mud from which the larve
are sucking out the decomposing matter which
forms their food.

It might be supposed that the Hristalis larve
have something to do with the cause of the
putrid condition of the mud in which they live ;
but this is not so. In fact, the reverse is the
case; and there is reason to believe that the
Fic. 251.—Larva mud they inhabit would be far more putrid than
or Hristalis tenax it is were it not for their presence, for they are

almost incessantly sucking up the decomposing
particles of organic matter to which the water owes its offensive
condition, and converting them into the harmless living substance
of their own bodies.

If we withdraw one of the larve from its miry bed, cleanse it
with running water, and then drop it into a glass of clear water
for examination, we shall be able to discern its form and to ob-
serve its movements. It is then seen to be of a dull greyish
colour and destitute of true legs, but provided with seven pairs of
very short retractile feet, something like the pro-legs of a cater-
pillar. These feet are circular in form, and each has a double
circle of little hooks adapted for prehension, and therefore useful
for creeping.

The most interesting feature of the larva, however, is un-
doubtedly the tail, which consists of two distinct parts—an outer
retractile tube, which is a direct prolongation of the skin of the
body, and a finer threadlike organ that telescopes within it.

q

AQUATIC INSECTS B15

This arrangement allows the larva to maintain a communication
with the atmosphere in water of different depths, at the same time
keeping its body in the mud whence it derives its food. If we
place the larva in very shallow water the length of the tail is
so adjusted as to reach the surface; and by gradually adding to
the liquid, we may cause the creature to protrude it more and
more, till at last it reaches its greatest possible length—more than
two inches—and is almost as fine as a hair at the end. If we now
continue to increase the depth of the water, the insect is unable to
breathe as long as it remains at the bottom, and so it endeavours
to creep up the sides of the vessel, keeping its tail extended to the
utmost limit as if feeling for the air, and will not rest till the
surface of the water is reached.

The breathing tube is transparent, and if we examine it with
the aid of a suitable magnifying power we can discern two tracheal
tubes running throughout its length. These are straight when the
telescopic tail is extended to its greatest length, but become neatly
folded into a series of loops when the tail is retracted. They
communicate with a pair of large dilated air tubes that run
through the body, and terminate in a pair of closed spiracles by the
head.

The movements of the telescopic tail, and the manner in which
the two air tubes become folded as the tail is retracted, are both
easily seen in the body of a young larva, which is sufficiently trans-
parent to enable the internal organs to be discerned. If we place
it in a very shallow glass cell filled with water and examine it
with a moderately low power, we can cause the tail to protrude
merely by the application of a gentle pressure on the body; and
each time the pressure is relieved the tail recedes, thus enabling us
to watch the manner in which the air tubes are folded.

When the larva is full grown it creeps out of the water, and
burrows into the soil in the neighbourhood of its pond. Its skin
then gradually becomes loosened from the body, and hardens so
that it forms, together with the earthy matter that adhered to it
while yet soft and moist, a kind of cocoon, within which the pupa
rests for a few days.

The perfect insect is very swift on the wing, and may be seen
throughout the summer flying from flower to flower, sucking out
the sweet juices after the manner of a bee. What a contrast is
this with the habit of the larva! The latter delighted in the most
foulsome mire and fed on its very essence ; but now the selfsame

516 LIFE IN PONDS AND STREAMS

insect, changed from an ugly maggot to a beautiful fly, seeks the
combined fragrance and sweetness of the choicest flowers.

We have spoken of this insect as beelike, but this similarity is
not confined to mere form and colouring, for, as we have just
seen, the insect is beelike in its habits. For this reason it is very
seldom touched except by the comparatively few persons who
know how to distinguish between the dipterous, stingless insects
and the hymenopterous insects, some of which are armed with a
sting. And the resemblance, which of course serves to protect the
fly against many of its enemies, is still further increased by a
strange habit which the fly exhibits when caught. Hold one by
taking its wings between the finger and thumb, and it will double
up its abdomen in the same threatening manner that a bee or wasp
would; and so determined are its efforts to apparently make the
tip of the abdomen touch the skin, that it is difficult to convince
the uninitiated that the fly really has no sting.

The specific name (Tenax) of this insect has reference to the
power with which it can hold on by its feet.

Aquatic LEPIDOPTERA

Those who are but little acquainted with the Lepidoptera—the
order of scaly-winged insects commonly known as Butterflies and
Moths—may be surprised to hear of aquatic species among them.
We are all familiar with the fate of the moth that accidentally falls
into a pond or into an open waterbutt. We have seen it struggling
in vain on the surface till the beauty of its wings is greatly impaired.
We know, too, the fate of the poor caterpillar who meets with a
similar mishap. Whether it sinks or floats, its body becomes wet
and its spiracles filled with water, so that breathing becomes im-
possible and the creature is soon drowned.

Hence our surprise on learning for the first time of caterpillars
that are capable of living beneath the surface of a pond, and
of moths that can even creep down the submerged stems of
aquatic plants, and return into the air with wings quite dry and
unsoiled.

It should be known, however, that of the many hundred species
of British Butterflies and Moths, only five have aquatic tendencies.
These we shall briefly describe ; but before doing so, we must become
acquainted with the distinguishing characteristics of the order to
which they belong.

AQUATIC INSECTS 317

If we handle a Butterfly or a Moth we observe that a dry dust
easily becomes detached from its wings. This dust, on examination
under the microscope, proves to be little scales of a definite form

Fic. 252.—-ScaLES FROM THE WINGS OF BUTTERFLIES, MAGNIFIED

that vary with the species as well as with the part of the wing from
which they are removed.

Then, if we examine the partially denuded wing we find that
the scales are neatly and regularly arranged in rows, each individual
scale being attached by means of a short stalk.

Fic. 253.—Porrion oF THE WING OF A BUTTERFLY FROM WHICH
SOME OF THE SCALES HAVE BEEN REMOVED, MAGNIFIED

Further, the wing may be completely denuded by means of a
soft brush, and then it is seen to consist of a thin transparent
membrane, supported by branching nervures.

In the Lepidoptera the metamorphoses are complete. The
larva, commonly known as the caterpillar, has a more or less

O18 LIFE IN PONDS AND STREAMS

cylindrical body of thirteen segments, counting the head as the first.
The next three segments correspond with the segments of the
thorax of the perfect insect, and each one bears a pair of legs with
hooked claws. Some of the other segments have membranous and
retractile ‘ pro-legs,’ each of which is armed with a circle of minute
hooks, enabling the larva to hold on with great tenacity. The

Fic. 254.—Winea or A Burrerriy, THE SCALES HAVING
BEEN REMOVED

number of pro-legs varies, but is commonly ten. At the sides
of several of the segments may be observed the stigmata or spiracles
—the openings by which the trachee communicate with the atmo-
sphere.

The head is provided with a strong pair of jaws which are used
for biting the food, and also, in some cases, for breaking up sub-
stances that are used in the construction of cocoons. There are also
a pair of very short and inconspicuous antenne, six pairs of simple
eyes, and a spinning apparatus consisting of a pair of glands, the

viscid secretion of which passes out through a duct that opens just.

under the mouth.
Caterpillars undergo a series of moults, and when fully grown

seek a secure spot in which to change. Those of the Butterflies
do not spin a cocoon of silk, though they often suspend themselves
from a silken carpet and make themselves secure by fixing a cord
of silk round the middle of the body. The larve of Moths, on the
other hand, often spin the most beautiful silken cocoons, or bind
together bits of leaves, particles of earth, or fragments of wood, &c.,
using the secretion of their silk glands for this purpose.

The pupe of the Lepidoptera are quiescent, though many of

AQUATIC INSECTS 319

them move vigorously at times,especially when irritated ; and they
are protected for the time being by a hardened, horny skin in
addition to any covering they may have prepared for themselves.

When the time for the final change arrives, the pupal skin
splits on the back of the foremost segments, and the perfect insect,
still with undeveloped wings, quits its case, and immediately
seeks a place where it can suspend itself while its wings expand
and dry.

The wings grow rapidly, being often fully developed in a few
minutes ; but they are still moist and limp, and quite useless for
flying. They soon become dry and rigid, however, and the insect
is then ready for its first flight.

The chief distinguishing feature between Butterflies and Moths
is to be found in the antenne. Those of the former are clubbed or
knobbed at the end, while those of the latter, though very variable
in shape, are always more or less pointed at the tip. All Butterflies
are diurnal in their habits, while Moths are usually nocturnal.
Butterflies, too, are often described as being more brightly coloured
than Moths, but it must be remembered that there are many of
the latter displaying the most gorgeous colours, while some of the
Butterflies are decidedly dingy.

We will now briefly consider our aquatic species of this order.
These belong to a family called the Hydrocampida, and the insects
themselves .form a little group of Moths popularly known as the
China Marks, on account of the nature of the pattern on the
wings.

They are slender-bodied insects, with long and slender legs
provided with long spurlike bristles, and the females are larger than
the males.

Our first example is the Small China Mark (Cataclysta Lemnata),
a pretty little moth that is common almost everywhere, and may
be seen flying among the vegetation on the ;
margins of ponds from June to August. The
wings of the male are white, with a small black
central dot and dark hind margin ; and the dark
band of the hind wings contains five minute ,, as

Bass : : Fic. 255.—Cata-
but bright silvery dots. The forewings of ¢jysta Lemnata
the female are brownish, with darker markings.

The hind wings are clouded with grey, and, like those of the male,
have small silvery spots near the hind margin.

The larva is of a brownish colour, and feeds on duckweed. It

320 LIFE IN PONDS AND STREAMS

makes a case something after the manner of the caddis larva, by
spinning together the fronds of the duckweed ; or sometimes it will
utilise a piece of a hollow stem found floating in the pond.

During the earlier part of the larva’s existence it is capable of
deriving air from the water; but after a time its stigmata become
functional, and it then obtains air direct from the atmosphere at
the surface of the water, or from the air supply enclosed within its
case.

If driven from its case it will soon construct another, provided
suitable materials be at hand, and this work is performed with
far more despatch than by caddis larve, the complete case seldom
occupying more than a quarter of an hour.

Another species—Paraponyx stratiotata—tfeeds on the Water
Soldier and other aquatic plants, and builds a case by binding leaves
together with silk. But this larva differs
from the last in that it breathes by branchiz
or gills until fully grown. Water passes into
its case, completely filling the space between
it and the insect. The latter, too, becomes
wetted, having no hairs or prominences on

Fie. 256.—Para- its body to resist the water film. Its respira-

ponyx stratiotata —_ tory organs consist of a number of little

bunches of filaments over the whole of the

body, each filament containing a branch of the tracheal system ;

and the larva promotes a circulation of water through its case

for respiratory purposes in the same manner as does the caddis
larva; that is, by an undulatory movement of its abdomen.

It will be remembered, too, that caddis larve have the front
segments of the body protected by a hard and horny covering, so
that they are safe against the attacks of at least some of their foes
while crawling and feeding ; and we find a similar protection in the
case of aquatic caterpillars, for in these the segment next to the
head is covered with a horny plate, and the head is capable of
retraction within this segment.

The larva of P. stratiotata is not fully grown when the winter
sets in, but it spends the cold season in a state of inactivity, remain-
ing concealed within its case till the April of the following year. It
then feeds again, grows rapidly, and pupates in May.

The pupa remains submerged, but the cocoon in which it changed
is full of air, and the spiracles, which were functionless during the

AQUATIC INSECTS 321

larval condition, now perform the work previously accomplished by
the brachial filaments.

The perfect insect may be seen on the wing from June to August.
It is larger than the last species. The forewings are yellowish
brown, with lighter and darker markings, and the hind wings are
white. The nature of the markings need not be described, since
they are carefully depicted in the illustration. The moth may often
be seen running on the surface of the water; and the female lays
her eggs on floating objects.

A third species, Hydrocampa nympheata (Plate V, fig. 5), is
very common in our ponds, and is popularly known as the Brown
China Mark. The moth varies from an inch to an inch and a
quarter across. The wings are marked with white and various
shades of brown, the details of which are shown in the coloured
illustration. It may be seen on the wing during June and July,
and lays its eggs on the under sides of the floating leaves of pond-
weeds (Potamogeton) and Water Lilies.

The caterpillar feeds on these plants, burrowing into the leaves
while very young and small, but living in cases of its own con-
struction after it has become too large to find a home between the
epidermal layers of the leaves.

The manner in which it constructs its case is very interesting.
It first cuts out a circular or oval piece of a leaf, the piece being
longer than its own body. It then applies this to a second leaf,
placing the coneave sides in apposition, and binds the two together
by means of the silk from its salivary glands. Sometimes it will
remain fixed to the plant in this way until it is obliged to travel for
further supplies of food, but sooner or later it secures its freedom by
biting away the side of its case.

At first the case is full of water, and the caterpillar derives its
air from the water, but it has no gills, and the manner in which it
breathes does not seem quite clear. Later in life, however, it con-
structs a case that resists the water, leaving an opening only just
large enough to allow its foremost segments to protrude, and this
aperture closes owing to the elasticity of the substance of which
the case is constructed when the caterpillar retires.

It hibernates during the winter, and is fully grown in May, at
which time it is about an inch in length.

When about to pupate it creeps up the stem of a semi-aquatic
plant, where it fixes its case and spins a silken cocoon within it.

We have two other aquatic moths, one being the Beautiful China

Y

822 LIFE IN PONDS AND STREAMS
Mark (Hydrocampa stagnata) (Plate V, fig. 6), and the other called
Acentropus niveus. The life histories of these insects are very
similar to those of the preceding species. The larva of the former
feeds on the pith and leaves of the Bur Reed, and that of the latter
on the pondweed Potamogeton pectinatus. Both hibernate during
the winter, and pupate in May or June; and the perfect insects fly
during June, July, and August.

AQUATIC COLEOPTERA

Most people probably think that they are competent to distin-
guish between beetles and other insects, and yet the fact that a
certain insect pest—the Common Cockroach—that belongs to the
Orthoptera or Straight-winged Insects is generally known as the
‘Black Beetle’ is ample proof to the contrary.

The chief character of the Coleoptera is that denoted by the
name of the order, a word which signifies ‘ horny-winged’; for the
outer wings of a beetle are of a hard and horny character, and not
parchment-like, as is usual with orthopterous insects. ‘These hard
outer wings (elytra) are not adapted for flying, but are merely pro-
tective, and form a complete covering for the second membranous pair,
which are folded up beneath them, and are usually organs of flight.

Beetles are to be found more or less in nearly every locality—on
land, under the ground, in caves, feasting in the interior of decom-
posing organic matter, in our provision stores, on the sea-shore, and,
what is most important to us at the present moment, in almost
every pond, ditch, and stream.

Some are ‘ water-lovers’ only in the sense that they occasionally
take a dive, but others spend nearly the whole of their existence on
or beneath the surface.

The number of aquatic beetles is very large, and it would be
impossible to give even a very short account of every one. So I
shall select a few typical examples, and deal with them as fully as
our space will permit.

The aquatic Coleoptera belong principally to three families—the
Dytiscide, Gyrinide, and the Hydrophilide ; and as some of the
species in different families are often very much alike in general
appearance, it will be necessary at the outset to learn how to dis-
tinguish between them. So, before describing individual species,
we must note the characteristic features of the groups.

In the first place, then, it must be observed that the Dytiscida
are more especially the predaceous family of water beetles, a fact

AQUATIC INSECTS

323

which is suggested by the comparatively large and powerful man-
dibles. Their antenne, too, are long and slender, and composed

of many joints; and their hind legs, which are
long and fringed with stiff hairs, are used after
the manner of oars.

The Gyrinide are commonly known as the
Whirligig Beetles, and both the popular and the
scientific names of the family have been given
on account of the active gyrations or whirling
movements of the insects as they paddle about
on the surface of the water. This family may
be readily distinguished by the nature of the
antenne, which are short and thickened; and
by the fact that the hind legs are short and
broad, while the front legs, which are short in
the Dytiscid@, are comparatively long.

Those of the third family—Hydrophilide—
are not so voracious as the Dytiscide, but subsist
more or less on a vegetable diet; hence we find
that their mandibles are comparatively small.
In the form of the legs they somewhat resemble
the Dytiscide, but they may be readily distin.
guished from the members of this latter family
by the antenne, which are clubbed or knobbed at
the extremity, and consist of fewer joints.

Fic. 257. — AN-

’ TENNA OF Dytt-
cusmarginalis,
ENLARGED

The character of the antenne may be seen at once by reference
to accompanying illustrations of the antenne of species from the

Q

Fic, 258.—ANTENNA OF Fic. 259.—ANTENNA oF
Gyrinus natator, EN- Hydrophilus piceus
LARGED (MALE), ENLARGED

typical genus of each family, and other important marks of distine-
tion will be illustrated when we come to the descriptions of the

types chosen.

¥2

524 LIFE IN PONDS AND STREAMS

No one could look at a typical water beetle without noticing at
once its adaptability for aquatic life. Its body tapers more or less
at both anterior and posterior ends, so that but little resistance is
offered to it as it moves through the water. The same purpose is
also served by the smooth and polished surface of the elytra and,
in fact, of all parts of the hard external covering of the body. Some
of its limbs are flattened and oarlike, and furnished with a row of
stiff bristles which can be made to stand out in the form of a fringe,
or to fall against the surface of the limb in such a manner as to be
hardly discernible. Thus the beetle, when swimming, can widen
the blade of its oar when propelling its body through the water, and
reduce the resistance offered to a minimum during the ‘ back-stroke,’
a feat that is accomplished by an oarsman by the movement which he
terms the ‘ feathering of the oar.’

Again, the forelegs, which are used almost entirely as organs of
prehension, either for seizing the prey or to anchor the body to
pondweeds or other submerged objects, are peculiarly adapted to
their work by being clawed and not unnecessarily long; while the
other legs, and especially the third pair which constitute the princi-
pal means of locomotion, are long and powerful, with the above-
mentioned fringe well developed, and the claws, unnecessary in this
instance, in a more or less rudimentary condition. Also, the hind-
most pair of limbs, which are the chief, if not the only ones used
in swimming, are joined to the body much further behind than
in the land beetles, which require all three pairs for walking and
running.

There is yet another important difference between the land and
the water beetles ; for while in the former all the limbs are jointed
to the thorax in such a manner that they can be moved vertically
as well as horizontally, thus enabling the insect to raise its body off
the ground as well as to push it onward, the swimming limbs of the
latter are capable of the horizontal or propelling movement only.
The vertical movement would of course be useless to a creature that
requires its legs only while submerged in water, and the peculiar
nature of the joint which thus restricts the movement of the swim-
ming limbs to one plane undoubtedly adds to their power as organs
of propulsion in water.

Water beetles are further gifted with considerable powers of
flight, though most of them are unable to start on the wing unless
they first obtain a foothold on the bank, on a floating object, or on
the exposed portion of an aquatic plant. They usually fly at dusk,

AQUATIC INSECTS 325

or during the dark hours of the night, and migrate over considerable
distances in search of suitable ponds in which to obtain their food or
to deposit their eggs.

In many cases they terminate their flight in a very peculiar and
abrupt manner. Finding themselves over the surface of a piece of
water, they suddenly close their wings and simply allow themselves
to fall into it. It is probable that in this matter they are enabled to
judge of their position with regard to the water by the sense of sight
only ; hence it is easy to understand that they may often be deceived
by reflections from bright surfaces other than those of ponds and
streams. It has often been observed that water beetles, thus de-
luded, have allowed themselves to fall on the glass roof of a green-
house. On one occasion, too, I myself observed a large one drop
directly on a garden path over which a pail of water had just been
thrown.

We must now leaye these general matters and proceed to ex
amine a few of our aquatic beetles in detail.

Dyticus marginalis

(Plate II)

We cannot do better than take Dyticus marginalis as our type
of the family Dytiscide@ ; for not only is it a fine, powerful insect,
of such a size that the beginner can easily make out its general
structure, but it is also so common and so widely distributed that
it is sure to turn up in the young collector’s net during the earliest
portion of his pond-hunting career.

It is a very easy matter to determine whether Dyticus' is at
home without making any use of the net. Simply approach a
pond very slowly and cautiously, and scan the surface of the water.
If this insect is present you will probably see it resting at the top,
with its body turned obliquely downward and the tip of its abdomen
just above the surface. Or, if it is not visible, remain perfectly still
for a minute or two, andif the species is present in the pond at all, it
will soon come to the surface to renew its supply of air, and either
rest there for a time, or immediately dart below again for an interval.
Whether you see it or not, make a few sudden dashes with the net
among the weeds near the banks, thrusting it towards the bottom
of the water and then sweeping it upwards.

This name is often wrongly spelt Dy/tseus.

d26 LIFE IN PONDS AND STREAMS

In this manner you may secure Dyticus in nearly every weedy
pond, even down to the tiniest puddle, only a foot or two in width,
or in ditches so narrow that there is barely room to play the
net.

Although the beetle is a large and powerful one, more than an
inch in length, you need not hesitate about taking it into your
hand. It never attempts to use
its powerful mandibles on such
occasions, though it may pos-
sibly prick your finger slightly
with spiny projections on the
under surface of its body. The
spines referred to project back-
wards from the metasternum—a
hard plate that forms a shield
under the hinder part of the thorax
—just at the bases of the hind
limbs. Simijlar spines are to be
seen on others of the Dytiscida,
but they vary in form in different
species.

Fic. 260.—UNDER SIDE OF THE When placed on the ground
Bopy or Dyticus marginalis, its movements are exceedingly
oa awkward. It cannot even drag

its body along with anything like
a steady movement, but jerks itself about in a fitful manner and in
all directions by throwing back its long hind legs. And if it is placed
on its back on a smooth level surface it has but little power of
righting itself, and spins round and round in a most ludicrous
fashion in its vain endeavours to find a foothold.

The upper surface of this beetle is of a very deep brown colour.
The thorax has a continuous yellowish margin all round, and the
elytra have a similar border on the outer side. The eyes are large
and very prominent, and are so situated that the insect is enabled
to look both upward and downward at the same time.

The under side is much lighter in colour, being principally of
the same yellow tint as the margins above.

There is a considerable difference between the male and female
Marginalis. The elytra of the former (Plate III, fig. 3) are smooth
and polished, and their surface is not varied in any way except by

AQUATIC INSECTS 327

three rows of very small punctures which are scarcely noticeable.
The elytra of the female (Plate III, fig. 3a), however, are deeply
grooved from the base to beyond the middle.

A still more interesting difference may be
seen in the front legs, the first three seg-
ments of the tarsi of the male being consider-
ably dilated, so that they form a plate-like
disc. This disc is really an important organ
of prehension, used principally by the male
for seizing and clinging to its mate; and
its structure is particularly interesting, and FIs. 261-—Forrtee

whe & Ren or THE Mate Dy-
should be examined by every one who has a ticus marginalis,
mucroscope. ENLARGED

On the under surface there are a large
number of circular suckers, the majority of which are very small,
but two are considerably larger. The smaller ones are stalked,
so that they are brought out on a level with the larger ones, and
thus the whole may be applied to a smooth surface to which the
insect desires to cling.

It was thought that these suckers were of a pneumatic character,
their adhesiveness being due to air pressure ; but there seems to be
no doubt that the power of their grasp is due to the secretion of a
sticky fluid.

The two distinguishing features just mentioned will enable one
to distinguish the sexes at once; but it should be known that the
surface of the elytra is not in itself an infallible mark, for occasionally
we meet with males that are furrowed, and females that are almost,
if not quite, as smooth as the majority of the males.

In order to study the habits of this insect we must transfer it
from our collecting box to an aquarium where it may be kept under
close observation; but, remembering its carnivorous nature, we
must be careful not to allow it to associate with other creatures to
which we attach any value. It seldom attacks its own species
(though it never hesitates to devour a dead companion), and it
does not as a rule kill water beetles of other species. Sometimes,
however, it-will attack these, and its jaws are sufficiently strong to
penetrate their horny elytra.

Soft-bodied creatures are eagerly devoured, and it is not slow to
prey on its own larvie. It will even seize fishes as they swim, and
mercilessly devour them as they struggle hard to shake off their
foe. Even molluscs are not proof against their ravages, for the

328 LIFE IN PONDS AND STREAMS

voracious Dytici will bite through their shells to feed on the soft
body within.

Further, they are not in any way particular concerning the
freshness of the food they devour, but are equally fond of decom-
posing flesh, and will feast greedily
on the carcase of a creature that
has been dead for a considerable
time. In captivity they may be
fed on flesh of any kind, and may
therefore be made to partake of
fragments of our own animal food.

There is one thing, however,
in which the keeper of these car-
nivorous beetles must be careful,
and that is, to see that the aqua-
rium is not allowed to contain
fragments of animal food over
and above that really required to
satisfy their voracious appetites ;
for such fragments, if allowed to
remain in the vessel, will decom-
pose and render the water most
offensive and dangerous. Such a
condition is generally indicated by
the turbid appearance as well as
by the unpleasant odour of the

ad ORO Takeda as Gah water ; and as soon as these signs

Dyticus, MAGNIFIED are noticeable the water should be
changed at once, and the super-
abundance of dead matter removed.

In transferring the beetles from the collecting box to the aquarium
we generally observe that they emit a fluid of a very unpleasant
odour; and should this fluid touch the fingers it will be found that
the objectionable smell is somewhat persistent, for it can be
detected even after the hands have been well washed.

The fluid referred to is of a milky appearance, and exudes from
the front part of the thorax; and the odour will probably recall
that of sulphuretted hydrogen gas to one who is acquainted with
the latter. In addition to this, the anal glands at the tip of the
abdomen also discharge a yellowish liquid that partakes of the
odour of ammonia.

AQUATIC INSECTS 329

Most carnivorous animals have their equally carnivorous foes,
and it is possible that even the sturdy and hard-bodied Dyticus is
occasionally attacked by larger and stronger creatures; but it is
highly probable that the fluids ejected from its body constitute a
valuable means of defence, and we can easily imagine that its body
would be hastily ejected from the mouth of its captor as soon
as the odour and perhaps also the taste of these fluids were realised.

As we watch the Dyticus in the aquarium we observe that its
body is considerably lighter than its own bulk of water, for the
insect cannot remain below without a foothold. Also, as it swims,
we find the body has a tendency to take an oblique position in the
water, the abdomen being higher than the head. This is best
observed when the insect releases its hold at the bottom and simply
allows its body to rise to the surface. At such times it rises tail
foremost, the tip of the abdomen first penetrating the surface film,
thus showing that this portion of the body is lighter than the fore-
quarters.

When it reaches the surface it generally remains there for a
time, raises its elytra a little from the body, and exposes a space
that contains air, thus leading us to suppose that the position taken
has some connection with the process of respiration.

And such is actually the case, for the space between the elytra
and the body is an air cavity, on the Hoor of which are the stigmata
or openings which communicate with the system of breathing tubes.
And thus, while the insect rests at the top of the water, it is enjoy-
ing the advantage of a free communication with the pure air above,
and at the same time keeping a watch below for any poor victim
that may happen to pass within its range. If now it is alarmed at
the approach of an enemy above, it immediately darts downward,
taking with it a supply of fresh air under the horny wings, and
often exposing a large silvery bubble at the extremity.

Dyticus marginalis may be found in ponds more or less all the
year round. Even in the depth of winter, except when the weather
is severe, it is resting and feeding among the weeds. Unlike the
majority of insects, it often survives more than one winter. It
would be impossible to ascertain its longevity in a free state, but it
is very common for the perfect insect to live over two years in a
state of captivity. I have at the present time three healthy speci-
mens remaining from a ‘take’ of about a dozen, that are now
entering their third summer.

The process of egg-laying may be watched in captivity, provided

330 LIFE IN PONDS AND STREAMS

the insects have plenty of room and the aquarium in which they
are kept is well supplied with weeds. The female makes a number
of incisions in submerged stems by means of the sharp blades of
her protrusile ovipositor, and deposits one or more eggs in each.
This is generally done during early spring, and the young larve
escape from the eggs in the course of a few weeks, the time varying
with the forwardness of the season.

The larve are very predaceous, though not active, and secure
their prey by stealth. They are of a dull
yellowish or brownish colour, hardly distin-
guishable from the mud on which they often
lie in ambush.

The body is elongated, tapering at the
tail, which terminates in a pair of fringed
appendages. The head is joined to the
thorax by a narrow neck, and all the seg-
ments of the body are distinctly marked.
The head is large and rounded, and furnished
with a pair of long and slender sickle-shaped
jaws, and six small eyes (ocelli) on each side.
The six legs also are long and slender, ter-
minating in a double claw. They are well
adapted for crawling over the mud and
among pondweeds, and, being fringed with
hairs throughout their length, are useful as
* swinuning organs.

Bak Bi Vee oe If we watch the larva as it moves about
Dyticus marginalis in the aquarium, we observe that its body

is lighter than water, so that it cannot remain
below unless it is anchored to submerged objects by means of its
hooked claws. The tip of the abdomen also is generally curved
upward.

When the creature wishes to breathe, it releases its hold and
allows its body to rise, still keeping the tail curved upward. On
reaching the top (Plate III, fig. 8c) the tail is thrust through the
surface film, and emerges into the air perfectly dry. ‘Then, since
the fringed appendages are not easily wetted, they serve to buoy up
the abdomen, while the forepart of the body is supported by the legs.

Air is then absorbed from the atmosphere into two tracheal
trunks—-one in each appendage ; and these trunks are continuous
with the two main air-vessels that run longitudinally throughout

AQUATIC INSECTS 331

the length of the body, and which give off branching trachee to
each of the segments.

In this position the larva is perpetually on the look-out for un-
wary victims that may come within its range, and such are seized
by a sudden pouncing movement of the body, and the equally sud-
den clasping of the sharp mandibles, which close within the body of
its prey, thus rendering all struggles useless.

Now the captor takes up a position of rest, and immediately
commences its meal; but no movement is to be observed in connec-
tion with its feeding, for it does not masticate its food, but simply
extracts the juices of its victim by suction through its jaws.

Its mouth is very rudimen-
tary, being represented by a
mere horizontal slit between the
broad labrum and labium; and
these two parts being generally
locked together, this slit is not
readily observed.

If we examine the mandibles,
however, we find that they are
grooved on the inner side, and
that the groove is covered by a
membrane and thus converted 2
into a tube, which is open at the Fic. 264.—Unper Sipe or THE
apex and at the base of the jaw. Heap or D. marginalis Larva,
It is through this tube that the "8°"?
larva sucks the juices of its prey, the power of suction being sup-
plied by a portion of the alimentary tube that is capable of being
enlarged by the contraction of certain muscles. These muscles
connect the walls of the cavity with the chitinous covering of the
head, and by their action convert the cavity in question into a kind
of suction pump. So effectual indeed is this apparatus, that the
body of the victim is drained till little is left but a transparent
framework that still retains the form of the original animal.

The larva grows very fast, and undergoes a series of moults or
changes of skin. It is fully grown in less than two months, and
then creeps out of the pond and buries itself in the soil in the
immediate neighbourhood of the water. It must of necessity leave
the water in order to undergo this change, for the pupa being
quiescent it could not rise to the surface at intervals in order to
renew the supply of air,

332 LIFE IN PONDS AND STREAMS

If the change is completed before the autumn sets in, the perfect
insect emerges in a week or two; but if pupation does not take
place until the season is well advanced, the insect hibernates in its
pupal condition, and emerges as soon as the sun of the following
spring is sufficiently powerful to call it forth.

When freshly emerged the perfect insect is pale in colour, and
its outer covering is soft and flexible, but it assumes the normal
appearance in the course of a day or two.

The other species of the genus Dyticus are so much like Margi-
nalis in general structure and habits, that the description just given
of the latter applies almost equally well to all, and in fact also to
the other genera of the same family. And as the family includes
over a hundred members and about eighteen genera, it will be
impossible to give the reader even a fair collection of types. We
will, however, figure a few other water beetles belonging either to
the same or an allied family.

The first of these is Hydroporus (Deronectes) duodecim-pustu-
latus (12-pustulatus), which represents a genus of small beetles,

Fic. 265.__Hydroporus 12-pustu- Fic. 266.— Agabus biguttatus,
latus, ENLARGED ENLARGED

of which the present species, though only about a quarter of an inch
in length, is one of the largest. They are also flatter than the
typical genus. The elytra are black, and marked, as shown in the
illustration, with six reddish-brown spots on each side—a feature
which has given rise to the specific name. This little beetle is very
common in some localities. Another species (Actliws sulcatus) is
shown on Plate III (fig. 4).

AQUATIC INSECTS 333

The next example—Agabus biguttatus—represents a rather
large genus of about twenty species, most of which are to be found
in running water. The thorax and abdomen are yellow, the former
with two small black spots at the middle, and the latter with a

Fic. 267.—Pelobius Hermanni, Fic. 268.—Cnemidotus impressus,
ENLARGED ENLARGED

larger bright yellow spot on each side. The elytra are also marked
with small dark brown dashes. This species inhabits running
water.

It will be observed that Hydroporus
12-pustulatus does not appear to be so
well adapted for aquatic life as Dyticus
marginalis. In fact it looks more like a
terrestrial than an aquatic beetle; and the
same remark applies to two of the remaining
three species figured, all of which are some-
times placed outside the Dytiscide family.
They are small beetles, two of them being
only about a sixth of an inch in length;
hence the figures are enlarged in order to
show more plainly the details of their mark-
ings. The largest of the three (Pelobius
Hermanni) is peculiar on account of the
strange rasping noise it makes when irri-
tated. This it does by rubbing the rough edge of the last segment
of the abdomen against the elytra.

4
Fic. 269.—Haliplus
variegatus, ENLARGED

334 LIFE IN PONDS AND STREAMS

WHIRLIGIG BEETLES (Gyrinid@)

I have already pointed out one or two important features by
which the Dytiscid@ may be distinguished from the Gyrumde, and
now we will take a well-known type of the latter family for exami-
nation.

One of the first things to attract our attention as we look on a
pond or stream is often a group of little oval creatures, with highly
polished bluish-black bodies that glisten in the sun like burnished
metal, sporting about with rapid gyratory movements on the
surface.

These are commonly called Whirligigs, or, more correctly, Gy-
rinide, both these names being suggested by their characteristic
whirling motions.

They are decidedly gregarious in their habits—at least, the
commonest species, Gyrinus natator, which we choose as our typical
example, is.

You wish to catch a few of these creatures, and so you make a
sharp dash with the pond net, of course not striking downwards,
but making a rapid horizontal stroke with
the ring of the net half submerged.

As soon as the stroke is over, not one is
to be seen on the spot where the little group
were sporting together, so you naturally
conclude that you have cleverly netted them
all. But on looking into the net you find
you are quite mistaken. Most of the little
beetles have made a sudden dive to the
bottom, performing the movement with such
rapidity that they escaped the snare.

Then you stand motionless for a time,
watching the surface, and one by one the
Fic. 270.—Gyrinus lively insects reappear as suddenly as they

natator, ENLARGED darted out of sight; and before many
minutes the little company have assembled
in the same little spot to resume their circular dance.

These beetles are very interesting in the aquarium, but they
should have plenty of room for their sports on the surface of the
water. There is, however, some little difficulty in keeping them
supplied with their natural food, which consists of various small

AQUATIC INSECTS 335

insects. In the outdoor pond or stream they probably subsist
largely on insects that accidentally fall into the water; but food
from this source would be at a minimum in an indoor aquarium,
and therefore it becomes necessary to introduce food for them.

It should be remembered, too, that they can fly well, provided
they can get a foothold, and consequently it is necessary to cover
the aquarium containing Gyrinus with gauze if their aérial excur-
sions are to be prevented. Even if there are no floating objects
on which they can rest while they unfold their wings, they seldom
have much difficulty in creeping up the sides of the vessel in
which they are placed, though the surface may be smooth and clean,
the slight adhesiveness of the water being sufficient to allow them
to push themselves up by the aid of their hind legs.

These legs are very broad, and fringed with stiff hairs, so that
they form admirable paddles for locomotion on the surface as well
as below. The forelegs are longer, and are used both for seizing
the prey and for prehensile purposes generally.

The body of Gyrinus being lighter than its own bulk of water,
the insect has to exert itself in order to dive below, and is obliged
to anchor itself when it desires to remain submerged. It breathes
much in the same manner as Dyticus, having an air space between
the elytra and the upper surface of the abdomen; and as it
swims beneath the surface the bubble of air that always remains
exposed at the tip of the body looks like a little ball of polished
silver. |

It will be seen from fig. 258 that the form of the antenna is very
peculiar, having the appearance of a double appendage. This is
due to the fact that the third joint is very large, and extends laterally
beyond the others before and behind it. Perhaps, however, the
most remarkable feature of the head is the form of the eyes. These
organs are double, each one being divided into upper and lower
parts that are quite distinct from each other. It is probable that
this arrangement enables the insect to see objects distinctly both
above and below it at the same time; and it has also been said that
the lower half of each eye is submerged as the beetle sports on the
surface of the water. If this is the case, the insect would be able
to see objects.in the water much more clearly than if its eyes
were elevated, for the vision would not be disturbed by the fitful
reflections of the water thrown up into ripples by its rapid move-
ment.

Gyrinus lays its eggs early in the summer on the submerged

336 LIFE IN PONDS AND STREAMS

stems of aquatic plants, and the larve are hatched in from one to
two weeks.

The larva is purely aquatic, and may be found in plenty
throughout the summer in most ponds, and also in the sheltered
nooks of streams. It has somewhat the appearance of a centipede
at first sight, but when-closely examined it will be found that only
three of its prominent appendages are true legs, the others being
fringed breathing organs, each one of which contains a breathing
tube that communicates with the air system of the body.

The legs are of course attached to the first three segments next
the head. All the remaining segments are furnished with breathing
appendages, each of the first eight having one
pair, and the last one two pairs.

The larva is predaceous, feeding on various
aquatic creatures, but is not nearly as voracious
as the larva of Dyticus. In fact, it has been
asserted that it will take to a vegetable diet at
times, either out of mere choice, or perhaps only
when the supply of animal food is insufficient
to satisfy its requirements.

When fully grown it leaves the water and
Fre, 271-—Lanva C°TeePS UP the stem of an aquatic plant. Here,

or Gyrinus, or Yather on the leaf, it constructs an oval

. ENLARGED silken cocoon, within which it changes to a
quiescent pupa.

The perfect insect usually emerges towards the end of the sum-
mer, at which time Gyrimuws may be seen in abundance almost
everywhere. When the chilly weather sets in, numbers of them
die off, but many protect themselves from the cold by burrowing
into the mud, where they remain in a dormant or semi-dormant
condition.

A long stretch of mild weather, even in the middle of winter,
will call them out from their hiding places ; and very early in the
spring they may be found in groups on the surface, the numbers
being great after a mild winter.

There are eight British species of the genus Gyrinus. The one
described is only a quarter of an inch in length, but another—
G. bicolor—which is found principally in brackish water, is con-
siderably larger.

One species, known as the Hairy Whirligig (Orectochilus vil-
losus), has its elytra covered with a fine short hair, This species

AQUATIC INSECTS 537

is very common in some of the rapid rivulets of Devon, and I have
taken many from the two streams which unite to form the river
Plym; but they do not seem to be abundant in many localities.
This insect does not play in the bright sun, as does Gyrinus, but
may be seen at dusk.

Hydrophilus piceus

Our type of the family Hydrophilide is the fine insect popularly
known as the Silver Beetle, and whose scientific name is Hydro-
philus piceus.

The popular name does not convey any idea of the actual colour
of the insect, for its body is of a very dark olive-green above and
black below. But a large area of the under surface is covered with

Fic. 272.—Hydrophilus Fic. §

273. -Hydrophilus piceus,
piceus, MALE MALE, UNDER SIDE

a short and thick yellowish downy hair which resists the water, and
the layer of air that remains permanently entangled between this
down looks just like a breastplate of bright silver if viewed in certain
lights when the insect is submerged.

This splendid beetle is the largest of our Coleoptera with the
exception of the Stag Beetle, and even this is but little superior in
point of size. And being almost perfectly harmless, it has naturally

Z

338 LIFE IN PONDS AND STREAMS

become a great favourite with keepers of aquaria, who have searched
far and wide for it in ponds and ditches; and thus its numbers
have been greatly reduced, while the destructive Dyticus marginalis,
generally neglected by the aquarium keeper, continues to show
itself almost everywhere in abundance.

The principal characters by which we are enabled to distinguish
between the Hydrophilide and the other two families of aquatic
beetles already considered are the short mandibles, the short and
clubbed antenne, and the comparatively long palpi which, in the
case of H. picews, are longer than the antenne.

On account of its superior size, H. piceus is not likely to be
confused with any of the Dytiscide except D. marginalis, the
largest species of the family; but the features mentioned above, as
well as the description which follows, will make the distinction
between the two insects perfectly clear, even to the most casual
observer.

It is usually more than an inch and a half in length, and about
three-quarters of an inch across the middle of the abdomen. The
thick yellowish-brown downy hair already referred to covers the
whole of the thorax and also the margins of the abdomen on the
under side.

The metasternum terminates behind in a sharp projection that
is directed backward—not two short and wide spines as in the case
of D. marginalis, but a single narrow and very sharp spine, more
like the point of a large needle; and as this spine is raised con-
siderably off the general surface of the body, it is very liable to
penetrate the skin of one who carelessly handles the insect, though
; the creature itself does not seem to know
&. how to make use of it as a weapon of
defence.

The forelegs are short, and terminate in
two rather large claws; and are used by the
insect as it creeps among the pondweeds,
as well as for prehensile purposes generally.
The tarsus is dilated in the male, forming a
Fic. 274. — ForeLec large triangular plate, and this feature serves

or Hydrophilus as 9 ready means of distinguishing between

Pee Se the sexes. The second and third legs are
long, especially the latter; and both these are used as oars when
the beetle swims. And here, again, we must note an interesting
difference between the present species and D. margimalis—this

————EE——————

.

AQUATIC INSECTS 339

time a difterence in habits; for while the latter insect moves its
‘oars’ simultaneously, H. piceus works its swimming legs alter-
nately, and is consequently not nearly so steady a swimmer as
the other. It is also far less active, and seems to prefer creeping to
swimming. .

The wings are very large and powerful, and the thin membrane
of which they are composed is supported by a few very strong
nervures.

It is probable that the long palpi are commonly mistaken for
the antennz ; for not only do they resemble the antenne of many
other beetles, but they are always well displayed, and even, it is

Fic. 275.—Hydrophilus piceus, wirH WINGS EXTENDED

supposed, perform the functions of antenne generally, being highly
sensitive. Then, again, the real antenne are closely concealed below
the projecting rim of the covering of the front segment of the thorax
in which position they are of service in assisting the process of
respiration.

Let us watch H. picews in the aquarium, to see how this process
is carried on. It rests at the bottom among some weeds, holding
on by means of itslegs. After a minute or two it becomes restless
and makes one or two creeping movements among the vegetation
Then it clambers among the tangled weeds till its body is free, and
swims upward till it reaches the surface. Here it takes up an

ZZ

340 LIFE IN PONDS AND STREAMS

inclined position with its head uppermost, and turns its body a little
on one side.

If we now look up at the under surface of the beetle we see the
silvery layer of air that covers the hairy portion of the integument.
It includes the whole under surface of the thorax, a transverse band
across the front portion of the abdomen, and the lateral margins of
the abdomen reaching to the tip. A lens will also reveal the fact
that the clubbed extremity of the antenna is covered with down, and,
like the surfaces just mentioned, cannot be wetted by water. Thus
this portion of the antenna is always surrounded by an air film;
and, lying as it does under the projecting edge of the front segment
of the thorax, its air film is continuous with that whieh covers the
whole downy surface, and this, again, is continuous at the margins
of the elytra with an air space between the elytra and the upper
surface of the abdomen.

Now, if we watch the insect closely as it rests at the surface of
the water, we find that it has brought the air film between the
thorax and the antenna on one side of the body into direct com-
munication with the outer air, and it is to attain this object that the
creature turns its body slightly on one side. Thus the whole layer
of air beneath the body is now connected with the atmosphere
above.

Further, as we watch the insect from beneath, we see the elytra
moving up and down, thus causing the air film to alternately swell
out and become thinner again. At the same time the whole body
of the beetle rises and falls with a gentle swinging motion corre-
sponding with that of the elytra.

Thus we get an insight into the interesting manner in which
the insect breathes. The action of the elytra reminds us of the action
of a pair of bellows. By their movement the air space beneath them
is alternately compressed and enlarged. Each time the space is
compressed, air is driven beyond the margins to the film beneath,
and thence to the point of communication with the atmosphere just
inside the antenna of the higher side of the body, and at this point
we can see the union between the submerged and outer air distinctly
by looking down on the water from above. The air thus expelled
carries with it the carbonic acid gas given off as a product of respira-
tion; and the specific gravity of the body being thus increased, it
falls a little in the water.

Immediately on this movement the elytra are raised again, thus
enlarging the air space over the body, and fresh air rushes in along

AQUATIC INSECTS 341

the same path to fill it up; and the specific gravity of the body
being again reduced, it rises.

After these movements have been repeated a few times, the beetle
swims below, carrying with it an abundant supply of fresh air. So
great is this supply, indeed, that the insect has to exert itself con-
siderably in order to reach the bottom ; and it often has to part with
a portion by compressing the air space beneath the elytra in order
to reduce the labour of the descent.

I should like to say much more concerning the interesting and
instructive habits of this beautiful aquarium pet, but must pass
on to a brief account of its metamorphoses. The reader, however,
is strongly recommended to hunt for it, and so be in a position to
investigate for himself. Use the net freely among the weeds of
stagnant water, dipping deeply and striking upwards; and if all
efforts are in vain as far as H. picews is concerned, procure a few
specimens from a dealer in aquarium pets rather than remain
personally ignorant of our finest British water beetle. Remember
that pond vegetation constitutes its principal food as well as its
natural home, and give it a very liberal supply.

The female is provided with a spinning apparatus which, like
that of the spider, is situated at the tip of the abdomen. By means
of this she spins a cocoon at the surface of the water, mooring it to
the stem or leaf of an aquatic plant. The cocoon is rounded, but
flattened on one side. Before it is finally closed she fills it with air
from her own personal supply, and then deposits within it from fifty
to a hundred white eggs. Her abdomen is next withdrawn and the
opening quite closed up; and she completes her task by spinning a
conical projection, half an inch or more in length, the purpose of
which does not seem quite clear.

The cocoon, soft at first, soon becomes hard; and being water-
tight, the eggs, and the young larve when hatched, are dry and well
supplied with air.

Fic. 276.—Larva or Hydrophilus piceus

Shortly after the larve have escaped from their prisons, they
find their way out of the cocoon and swim away into the water below,

342 LIFE IN PONDS AND STREAMS

The larva is a soft-bodied grub of a dull greyish colour, tapering -
off considerably towards the tail, and also slightly towards the
head. The latter is black and shining, and the three pairs of legs
are short in proportion to the size of the body.

It is a predaceous creature, as may be surmised from the nature
of its large curved jaws, and feeds on molluses and other inhabitants
of ponds.

Like the perfect insect, it breathes the atmospheric air direct,
coming to the surface at intervals for the purpose of renewing its
supply. The exchange of air is carried on through the agency of
the fringed appendages of the tail, which are thrust above the surface
for that purpose. Each appendage contains an air tube that forms
part of the tracheal system.

The larva undergoes three or four moults, and is full grown in
July or early August, when it leaves the water and burrows into
the soil in the neighbourhood. Here
it constructs an oval cell, the walls
of which are strengthened by a
glutinous substance from its own
body. Within this cell the pupa
lies perfectly inactive till the time
arrives for its emerging. All the
organs of the perfect insect are now
to be seen, each one encased in its
own sheath; and the creature is
Fic. 277.—Pura or Hydrophilus provided with no less than eight

pews prominent hooked appendages, three

on each side of the head, and two on

the tail. These support the body as it lies in the cell, and so keep

it from contact with the soil. These appendages are thrown off
with the cast skin when the perfect insect emerges.

The family Hydrophilide contains about ninety British species,
all of which resemble each other in habits and in general structure,
but exhibit great diversity in the matter of size.

There are other aquatic beetles in addition to the three families
Dytiscida, Gyrinide, and Hydrophilide, of which we have selected
typical examples, but space can be found for only one other—a repre-
sentative of the family Parnide.

This family contains fourteen British species, some of which are
to be found in the water of ponds and streams, while others frequent
the surface and the wet muddy banks. ‘They are mostly very

AQUATIC INSECTS 343

small beetles, with the head sunk deeply into the first segment of
the thorax.

Our illustration represents one of this family. It is a very small
insect, named Elmis @neus, the latter term
being applied on account of the characteristic
brassy colour of its surface.

The thorax is abruptly squared in the
front. The elytra are marked with longi-
tudinal rows of small punctures, and the
under surface is covered with a thick short
hair of a bright yellow colour.

This insect inhabits streams, even very
rapid ones. It will be seen that all its legs
terminate in sharp double claws, and by
means of these it fastens itself securely to
submerged objects, thus preventing itself Fic. 278.—Elmis
from being carried away by the current. @neus, ENLARGED

Aquatic HYMENOPTERA

The Hymenoptera, or ‘ Membrane-winged Insects,’ form a very
extensive order, and include not only Ants, Bees, and Wasps, but
also large numbers of Gall Flies, Saw Flies, and Ichneumon Flies.

The general characteristic of the order is the two pairs of naked
membranous wings, supported by only afewnervures. The mouth
is also adapted both for chewing and for suction, the mandibles
being strongly developed, and the labium and maxille prolonged
into a sucking tube.

The abdomen is often joined to the thorax by means of a very
slender threadlike waist, and the hindmost extremity of the body
is furnished either with a sting or with an ovipositor.

The Hymenoptera include more than thirty thousand known
species, and till about thirty years since not a single one of aquatic
habits had been discovered. However, in 1863 Sir John Lubbock
published an account of two minute, perfect, hymenopterous insects
which he had found swimming in water, and we need hardly add
that the discovery came as a great surprise to entomologists, who
could hardly have expected to meet with insects possessed of such
delicate wings moving uninjured beneath the surface of water.

It was evident at once that the insects in question were closely
related to the group commonly known as Ichneumoen Flies, which

344 LIFE IN PONDS AND STREAMS

deposit their eggs on or within the bodies‘of other animals or, in
some cases, in the cuticle of plants.

Before describing the aquatic species made known to us by the
untiring observations of this eminent entomologist, it will be well
to note the general habits of the _Ichneumon Flies.

They are provided with long and slender ovipositors, most of
which are capable of piercing the living tissues in which they lodge
their eggs. The majority of them fly about among plants, carefully
searching the leaves and stems for the larve of Lepidoptera and
other insects. Each one generally shows a marked preference for
some particular species, confining its searchings to the favourite
food-plants of that species. Having met with a victim, it pierces
the skin and thrusts one or more eggs within the body.

The larva thus wounded is apparently none the worse at first,
the puncture being very small, and the presence of the egg or eggs
causing little or no inconvenience.

But after a short time the eggs are hatched, and the little grubs
of the ichneumon fly at once commence feeding on the body of
the unfortunate host, which becomes both the home and the food of
its internal foes.

The larva continues to feed, and apparently to grow; but the
nourishment taken builds up tissues which have only a transitory
existence, for they are greedily devoured by the parasites, which
grow rapidly, and thus maintain and even add to the size and
general plumpness of their victim.

The ichneumon larvee, however, generally avoid the vital organs
of the body on which they feed, as though they knew that by this
precaution they could maintain their supply of provisions and pre-
serve their home ; but subsist principally on the fatty matter stored
beneath the skin of their host.

Thus the infected larva may live to the end of its usual term,
and even successfully undergo its metamorphosis to the pupal state.
But when this is the case it seldom has the strength to emerge
in the perfect condition, and one or more ichneumon flies having
passed completely through their changes, eat their way through
the pupa, often leaving it not only lifeless, but a mere hollow
shell.

Sometimes, however, the ichneumon parasites attack the vital
parts of their prey, which is thus reduced to an empty skin before
the transformation can take place.

Such is the life of many of the ichneumon flies, and we need not

AQUATIC INSECTS 345

now detail the life histories of those which differ from the general
rule in minor particulars.

Two aquatic species were described at the time above mentioned.
One of them, named Polynema natans, is only one-twentyfifth of
an inch in length. Its .
wings are quite devoid of
nervures, but are sur-
rounded by a fringe of
fine hairs. It crawls over
the submerged leaves and
stems of aquatic plants,
and even swims, with a
slow and jerky motion,
beneath the surface by
means of its delicate
fringed wings.

At first it was thought that the flies seen in the water were
females engaged in searching for aquatic larve in which to deposit
their eggs, but it was soon found the males as well as females were
in the habit of making these aquatic excursions.

Another species, discovered about the same time, swims by
means of its legs instead of its wings; and subsequently several
others have become known through the energies of various natu-
ralists. Some of these prey on the bodies of caddis larve. Others
have been bred from the larve of water beetles ; and one very small
species, closely allied to Polynema natans, deposits its eggs within
the eggs of dragon flies.

It is interesting to note, in conclusion, that the aquatic ichneu-
mons are apparently but ill adapted to their peculiar mode of life.
Their bodies are not pointed in such a manner as to allow of easy
motion through the water. Their legs are not flattened and fringed
with bristles, like those of most of the aquatic beetles and the
‘boatmen.’ Neither have they any special provision to allow the
process of respiration to continue while their bodies are submerged.
They breathe by means of stigmata like the aérial Hymenoptera,
and therefore are not able to remain below any longer than the
scanty air supply within the tracheal tubes will allow. This time,
however, seems to be considerable in some species, for we are
told that they can be kept below the surface for several hours
together without injury.

Fic. 279.—Polynema natans, ENLARGED

346 LIFE IN PONDS AND STREAMS

CHAPTER XI
FISHES FOR THE AQUARIUM

HirHERTO we have been giving attention only to the invertebrate
division of the animal kingdom, but now we must devote a little
space to aquatic backboned animals.

The Vertebrates are usually divided into five classes—Fishes,
Batrachians, Reptiles, Birds, and Mammals, the first three of
which contain cold-blooded, and the others warm-blooded animals
All the five classes possess water-loving creatures, but the Fishes
and the Batrachians alone include animals that are structurally
adapted to a purely aquatic life, the former throughout the whole of
their existence, and the latter generally during their earlier stages
only.

The adaptation to aquatic life to which we refer is shown not
only in the general form of the body and the possession of organs
for swimming, but, what is far more important, in the possession
of organs by means of which air can be separated from the water
in which they live. Thus the creatures in question need not come
to the surface to breathe, but are enabled to derive all the air required
for the aération of the blood from the water itself.

In the present chapter we shall consider the fishes—-the lowest
or simplest class of the Vertebrates; and must necessarily con-
fine our attention to a few that lend themselves most readily to the
more or less artificial conditions of an indoor aquarium or of a small
garden pond; and we will first note the general characters of the
group or class to which they belong.

In general form they are particularly adapted for moving in
water, the body being either elongated and tapering before and
behind, or flattened and sharp at the edges, and in either case
capable of motion in water with but little resistance.

The limbs, if present at all, are arranged in pairs, and are modi-

FISHES FOR THE AQUARIUM B47

fied into fins for swimming ; and in addition to these paired appen-
dages there are generally other fins along the middle line, as well
as the terminal tail fin, which constitutes a very powerful propeller.
These, however, do not represent the true limbs of the higher
vertebrates, but are outgrowths of the covering of the body.

The surface of the body is either naked, or covered with over-
lapping scales or hard and bony plates.

On each side of the body there is a line of scales extending from
the eye to the tail, usually of a different colour from those above
and below them, and each scale perforated by a small hole which
leads into a little sac that is supplied with a nerve filament. These
little cavities are supposed to be organs of sense, though the exact
nature of the sensation or sensations produced by means of them
has not been ascertained.

Vee
ij,
<< Ca

LY
RE

Fic. 280.—SKELETON oF A [isn (PERCH)

d, dorsal fins ; v, ventral fin ; a, anal fin; p, pectoral fin; ¢, tail fin

In some of the lowest fishes the internal skeleton is cartilaginous,
but in the majority there is a well-developed bony skeleton consist-
ing of a backbone surmounted by a skull, and giving attachment to
the paired fins and the ribs.

The backbone usually consists of a chain of bony dises which
are concave both before and behind. Each dise or vertebra gives
rise to a bony arch above, and the summit of the arch is prolonged
into a long spine. The series of arches thus formed serve to enclose
and protect the great central nerve—the spinal cord—- which proceeds
direct from the brain, and the brain itself is enclosed and protected
by certain bones of the skull.

548 LIFE IN PONDS AND STREAMS

Some of the foremost vertebre give rise each to a pair of ribs,
and these ribs form a series of bony arches on each side of the cavity

Fic. 281.—Tuer Crrcunation or Broop

IN A FIsH
A, aortic bulb; H, heart ; B, arteries supplying
gills; V, veins; b, veins conveying aérated
blood from the gills to the dorsal aorta; a,
dorsal aorta ; L vessels of liver; A’, kidney

that contains the internal
organs. The other vertebrae
have each a V-shaped bony
arch below, corresponding
with that above, and this
series of arches affords pro-
tection to the great blood-
vessel (the aorta) which sup-
plies blood to the different
parts of the body.

We may also note briefly
the general characters of the
internal organs.

The digestive tube is of
very simple construction,
and there is no provision
for the mastication of food;
for although most fishes are
provided with teeth, these
are usually comparatively
small, and adapted only for
seizing and holding their
prey. The teeth are gene-
rally small and pointed, and
arranged round the edges of
the jaws; but in some cases
they exist more or less on
all the bones around the
cavity of the mouth, and in
others are situated only on
the living membrane. They
are generally renewed
throughout life as fast as
they become worn away.

The heart is situated just
behind the head, and con-
sists of two cavities — an
auricle which receives im-
pure blood from the veins

FISHES FOR THE AQUARIUM 549

after it has circulated through different parts of the body; and
a ventricle, which receives the blood from the auricle and then pro-
pels it to the gills, where it becomes oxygenated. From the gills it
flows through several parallel veins to the aorta, which sends it to
all parts of the body.

The gills consist of fringed folds, richly supplied with blood, and
situated either beneath moveable gill-covers or within pouches which
communicate freely with the water outside. Water is being con-
tinually taken in at the mouth, and passed out again at the gill-slits
just behind the head. As it passes over the gills dissolved oxygen
is absorbed into the blood through the thin and soft structures that
separate this fluid from the water, and at the same time carbonic
acid gas that has been gathered up by the blood during its circulation
in different parts of the body is given out to the water in exchange.
Thus the gills of a fish perform exactly the same function as the
lungs of the higher air-breathing animals ; but as they are not adapted
for carrying out this exchange with the atmosphere direct, fishes
cannot as arule live for any great length of time out of water.

Some fishes, however, are furnished with an accessory breathing
organ, by means of which the blood is aérated by air obtained direct
from the atmosphere ; and in certain cases the creatures in question
are so largely dependent on this source of supply that they can
actually be killed by suffocation—drowned, in fact—by preventing
them from reaching the surface.

Most fishes are provided with a membranous sac called the air-
bladder or swimming-bladder. It lies just in front of the vertebral
column in the visceral cavity, and contains air. In some cases it is
quite closed, but it generally communicates with the intestine. This
bladder can be compressed or dilated, and thus serves to regulate the
specific gravity of the fish so that it can rise or sink in the water
as it desires.

There are yet a few interesting characteristics of fishes that
remain to be considered. The brain is of a very low type, and the
organs of sense are of a very simple and imperfect character. The
ears are simple sacs, situated in the brain cavity ; and these are filled
with a fluid in which float small solid stony bodies which assist in
transmitting vibrations to the nerves that ramify in the walls of the
sacs.

Some fishes have no tongue, and when that organ is present it
is small and not capable of protrusion out of the mouth.

Finally, I must say a word concerning the colouring of fishes.

350 LIFE IN PONDS AND STREAMS

In some we find the most gorgeous tints, often exhibited in great
variety in the same species ; but the most interesting feature in this
connection is the remarkable protective colouring of such a large
number. Thus we often find the upper surface of those species
which live on the bottom bearing such a close resemblance to the
mud on which they rest that they are practically invisible to the
numerous enemies above. Also, those species which swim at or
near the surface are frequently coloured above with the same olive
tints that characterise the water itself when viewed from above, and
thus they are hardly visible to the fish-eating birds which hover
over the water. At the same time these fishes are protected from
their enemies below by the bright silvery colour of their ventral
surface, which is scarcely to be distinguished from the colour of the
sky by creatures beneath them.

Fishes are divided into several orders, iit ‘lowest of which
includes the Pouch-gilled Fishes (Marsipobranchi) or Lampreys.
These fishes are remarkable for the peculiar structure of their gills,
which are little pouches, six or seven in number on each side,
arranged in two rows. They communicate with the exterior by
means of small punctures, and the blood, which circulates freely in
their walls, is aérated by the absorption of oxygen from the con-
tained water.

In general form Lampreys resemble worms rather than fishes,
their bodies being long and cylindrical, and they have no paired
appendages corresponding with the pectoral and ventral fins of the
majority of the sub-kingdom; but they have two dorsal fins, the
hindmost of which is continuous with the tail fin. They further
resemble worms in that their bodies are quite devoid of scales.

They feed somewhat after the manner of leeches, having a circu-
lar suctorial mouth, by which they cling to their prey, or rather
their hosts, for they attach themselves to fishes and other animals,
often considerably larger than themselves, and rasp away the living
flesh with their small but numerous teeth.

These teeth are situated not only on the upper and lower margins
of the mouth, but also on the sucking disc and on the tongue; but
it is a curious fact that Lampreys undergo metamorphoses, like
their nearest relatives of the invertebrate animals, the young differ-
ing from the adults not only in the absence of teeth, but also in the
arrangement of fins, and the concealment of the eyes in a groove.

The River Lamprey (Petromyzum fluviatilis) is still to be found
in some of our rivers and lakes, especially those whose beds are

FISHES FOR THE AQUARIUM 351

situated on low ground near the sea. At one time they were extremely
abundant in the Thames, Severn, and several other British rivers,
and were used largely as an article of diet ; but now they are scarce
in many of their former haunts, and are caught chiefly for bait.

This tish has been taken in the sea, and it is possible that it
commonly spends a portion of its existence in salt water, ascending
rivers at regular seasons in order to deposit its spawn.

We can hardly recommend the Lamprey as an ornament to the
aquarium, nor can any hopes be entertained of keeping the fish
alive for any length of time in a small tank; but we strongly
recommend those who are unacquainted with this curious creature

Fic. 282.—Tuer River Lamprey (Petromyzum fluviatilis)

to procure one alive, and observe its form, and its habits as far as
they can be studied in confinement. It cannot fail to be interesting
on account of its unfishlike nature. Like worms and leeches it
has no true jaws, no ribs, and no limbs; and were it not for the
rudimentary spine, which, by the way, is not a true bony structure
as in most other vertebrates, we should probably class the creature
with the Vermes division.

Passing over the Sharks and Rays, and also the Ganoid Fishes,
whose bodies are covered with hard and polished plates, both of
which orders are not represented in our ponds and streams, we

B52 LIFE IN PONDS AND STREAMS

come to the extensive order of bony fishes (Teleosti), or fishes
whose skeletons are composed of true bone.

This order includes all our freshwater fishes with the exception
of the Lamprey already mentioned. Their bodies are covered with
scales, and their gills are composed of comblike fringes, supported
on bony structures, and situated under gill-covers at the back of the
head.

Although all the Teleostw resemble each other in the particular
just mentioned, yet they include an enormous assemblage of fishes,
exhibiting a remarkable diversity of form and habit; hence they
are divided into sub-orders, which are further split up into families.

The principal sub-orders are—

1. The Tube-bladdered Fishes (Physostomz), distinguished by
the presence of a duct which forms a means of communication be-
tween the swimming-bladder and the digestive tube (fig. 283). The

Fic. 283.—INTERNAL ORGANS OF ONE OF THE Physostomi (HERRING)

a, esophagus ; bce, stomach; ¢, intestine; 7, duct of swimming-bladder ; 4, swimming-
bladder ; 4, ovary or egg-producing organ

fin rays are also soft and flexible, and made up of several jointed
parts, with the exception generally of the front ray on each fin,
which is hard and spiny.

2. The Soft-finned Fishes (Anacanthini)—another group of
soft-rayed fishes, in which even the front rays are flexible, and in
which the swimming-bladder, if present at all, has no duct leading
to the digestive canal.

3. The Spine-finned Fishes (Acanthopterygu), with hard and
spiny fin rays, and in which the hind margin of the scales is ser-
rated or spiny. These also have either no swimming-bladder, or
the same has no duct.

There are other sub-orders of the Teleostii, also another order
containing only three fishes; but these do not include any species

PLATE VI.

Danielsson & Co., London, del. ad. Nat. et Chromolith,

FISHES FOR THE AQUARIUM 353

which concern us at present. We will now proceed to note briefly
some of the species to be found in our ponds and streams, and which
may be studied in the aquarium.

The Tube-bladdered Fishes include Eels, Carp, Gudgeon (Plate
VI, fig. 1), Barbel, Rudd, Minnow (Plate VI, fig. 2), Roach, Chub,
Dace (Plate VI, fig. 3), Tench, Bream, Bleak, Loach, Pike, Salmon,
Trout, Grayling, and Charr. Of course some of these are not likely

Fic. 284.—Tuer Buieak (Alburnus lucidus)

to come in the way of any but experienced anglers, and others are
not at all suitable for small aquaria; still there is no reason what-
ever why any small fish captured by the owner of an aquarium
should not be kept, at least for a time, so that its movements and
habits may be observed.

Several species that are not easily reared in small aquaria may
do very well in a garden pond, but in the latter they are not gene-
rally so easily watched as in a glass tank.

We have already dwelt on the importance of maintaining con-
ditions for our aquarium pets as closely as possible corresponding
with those under which we find them in nature, and this is especially
important in the case of fishes.

Some, such as the Bullhead, delight in shallow and rapid
streams with stony bottoms, while others are found in the deep and
muddy holes of sluggish rivers or among the weeds of still or running
water. And though some species do well under conditions more
or less at variance with those which are natural to them, yet it will
be wise to follow nature as closely as possible, even though by so
doing we may find observation less easy, and possibly also cause
our aquarium to look rather less picturesque than we would have
it be.

Again, if we are not acquainted more or less with the habits of
fishes before we venture to put different species together, we must
be prepared to gain experience at the cost of the loss of some of
our specimens, Some species will prey on others, fish constituting

AA

B54 LIFE IN PONDS AND STREAMS

their natural food; and others are exceedingly pugnacious, and
always ready to attack out of mere ferocity.

I have placed a small Jack, one about nine inches long, in an
aquarium with several Roach and Carp almost as large as itself ;
and although they lived together for several months, and the Jack
was well supplied with suitable food, yet their life was not one of
peace, and the grazed flesh of the harmless species, exhibited in
spots where the scales had been torn away, showed the advisability
of removing the Jack to other quarters. In this case the marks of
injury left not the slightest doubt that the Jack had frequently
endeavoured to perform an impossible act—to swallow a fish of
almost equal size to itself—although I had never caught it in
the act.

No fish has become such a universal favourite for the aquarium
as the Gold Fish or Golden Carp (Cyprinus awratus). This fish
is said to have been introduced into England from China in the
early part of the seventeenth century, and it has now become so
far acclimatised that it weathers our severest winters in outdoor
waters.

It is certainly a very pretty fish, and its value is enhanced by
the great variability in its colouring, the bright orange tint being
often relieved by patches of black, brown, or white.

Like the Common Carp (Cyprinus carpio) of our ponds, it is
quiet and inoffensive, feeding on small worms and insects and on

Fie. 285.—Tue Care (Cyprinus carpio)

the young shoots of various pond plants, and displays marked gre-
garious tendencies.

30th these species are valuable in the aquarium; for, being
almost always on the move, they give life to the scene when other
inmates are hiding under the shelter of stones or weeds. For the

FISHES FOR THE AQUARIUM 355

same reason they are useful fish with which to stock a small garden
pond. They sport about at and near the surface, chasing each
other among the floating and standing weeds, and occasionally
taking a leap into the air.

There is no difficulty in obtaining Carp for the aquarium.
Young ones will be frequently found in the net that has been dashed
among pondweeds when striking for aquatic insects, and those
taken with the rod and line are generally so slightly injured as to be
apparently none the worse. A red worm is a satisfactory bait, and
as a rule the carp bites freely.

For small aquaria the Minnow (Leuciscus phoxinus—Plate VI,
fig. 2) is admirably adapted. It is very prettily marked, especially
during the breeding season—early in May; but if it is required to
breed Minnows in captivity, they should have plenty of room and
be well fed, or, like many other fishes, the Carp included, they will
devour their own young.

Minnows prefer running water, and if kept in captivity should
be provided with a permanent fountain, with of course a pipe to
carry off waste.

The Roach (Leuciscus rutilus) also thrives well in captivity,
provided the aquarium is adapted to the size of the specimens

Fic. 286.—Tue Roacu (Leuciscus rutilus)

obtained. It is not so easily caught as the Carp, being very sus-
picious, and inclined to avoid the angler’s float. It is also very
particular as to its food, but will usually bite at gentles (the larve
of the Meat Fly), or at boiled wheat grains. The finest tackle
should be used by the angler.

I have not space to enter into particulars concerning the
majority of the species belonging to the present sub-order, but will
refer briefly to one or two of the bottom fish—those heavy-bodied
fish which lie on the bed of the pond or stream, and which cannot
rise without a considerable amount of exertion.

>
-
ao

356 LIFE IN PONDS AND STREAMS

Such fish are usually provided with barbules on each side of
the mouth, and their bodies are not compressed laterally.

One of these, the Gudgeon (Gobio fluviatilis—Plate VI, fig. 1), I
have found thrive well in a large aquarium, where it delights to lie
with its kind among the densest weeds, often remaining perfectly
still for a long time together.

Gudgeons have been described as purely animal feeders, but in
captivity at least they feed readily on bread crumbs and other
vegetable diet, swimming up to the surface to snap at the floating
food as soon as it is thrown to them.

But perhaps the most interesting of the bottom fish is the
Common Loach (Nemachilus barbatulus). It is to be caught in
many small ponds and ditches, and is sometimes found in such a
small quantity of water that no apparatus is required to catch it,
for it is unable to get beyond the reach of the hand. In any case
there is generally no difficulty in obtaining it by means of the
ordinary pond net, which should be made to serape along the
bottom.

Fic. 287.—Tue Loacu (Nemachilus barbatulus)

Although essentially a bottom fish, the Loach will frequently rise
to the surface, and even remain there for some time, providing it
has a suitable resting place. If kept in a small aquarium, I should
advise the introduction of a root of Potamogeton natans; or, if in
a small pond, either this or one of the Water Lilies. The floating
leaves of these plants form admirable supports for the Loach when
it desires an airing and sunning, and thus enable us to watch and
feed it with ease.

The Actinopterygii include a few of our freshwater species.
They are so called because of the radiating or fanlike disposition of
the fin rays.

Two of these belong to the Perch family, and these are the
Common Perch (Perca fluviatilis—Plate VI, fig. 4) and the Ruffe
or Pope (Acerina cernua). These are very similar, and both are to
be caught in sluggish streams.

The Perch is certainly one of the prettiest, if not the prettiest, of
our freshwater fishes; and is a perfect ornament in the aquarium ;

ee -

FISHES FOR THE AQUARIUM 357

but it does not seem to take so kindly to captivity as many other
species.

It is a very voracious fish, and feeds readily on worms, small
frogs, tadpoles, minnows, and the fry of other fishes.

For voracity combined with pugnacity, however, we shall hardly
finda match for the Common Stickleback or Three-spined Stickleback
(Gastrosteus aculeatus—Plate VI, fig. 5). It will eat almost every
living thing that comes in its way, provided it is small enough to
be swallowed; and even when it is not, the fish will often struggle
hard to devour it before the case is finally given up as hopeless.

The pugnacious character of this little creature is seen to per
fection when a worm, about twice as long as its own body, is thrown
into its home. The wriggling worm is seized, regardless of its
dimensions, without the slightest hesitation, and the Stickleback at
once commences its impossible task. Others appear on the scene
immediately, and then a fierce quarrel commences. The holder of
the worm tries to carry it off to avoid the interruption of its
companions, but is pursued by them, and shortly we find three or
four tugging at the poor worm, while perhaps a dozen others are
fighting for their share of the feast. All have their three strong
dorsal spines erected in readiness for the offensive, and it is not at
all uncommon, on such occasions, for one, furious and disappointed,
to strike one of its fellows from below, and literally rip up its body,
and then, leaving it in its death struggles, to renew the chase for
the prize.» And so the fight continues, till at last the poor worm
has been killed, torn to fragments, and eventually devoured by the
voracious group.

But it is not only at feeding time that this pugnacity is dis-
played. Simply plunge the end of your stick into the water where
the Stickleback swarms, and the intruding rod is charged with such
force that you can even feel the blows given to it by their bony
jaws, the charges being renewed every time the stick is moved. It
will also attack fishes very much larger than itself, frequently deal-
ing a deathblow to the victim that ventures within its precincts ;
and even the largest of the water snails are charged by its powerful
jaws if they venture to expose their soft bodies within its range.

No instructions need be given for the capture of this pugnacious
but interesting little king of the ponds. We are all familiar with
the schoolboy’s method of dangling the tempting worm on the end
of a yard or so of cotton thread. He needs no hook; but simply
allows the Stickleback to swallow the worm, or part of it, and then

358 LIFE IN PONDS AND STREAMS

suddenly jerks the fish out of the water before it has had an
opportunity of disgorging its meal. But here is a simple method of
securing a considerable number in a short time: Place your pond
net, rim uppermost, about a foot below the surface of the water.
Then introduce the end of a stick, and keep it moving just above
the net till a group of the infuriated ‘ Titlers’ are busily engaged in
the charge, and a sudden upward stroke of the net will then secure
them all. Thus we need no bait, in the usual sense of the term,
but merely turn their natural pugnacity to our own account.

It is during the breeding season in early summer, however, that
the Stickleback is most interesting. At this period the male is
adorned with the most brilliant colours; and then, too, his fury
knows no bounds. He constructs a rough nest for his bride by
matting together any fibrous materials at hand. Within this nest
the female deposits her eggs; and from this time till the young have
hatched and dispersed to seek their own livelihood he will never
leave his charge, day or night, and will furiously attack any moving
thing that ventures within a foot or so of the nursery.

Although the Stickleback is apparently so hardy and strong,
yet it requires some care in confinement. The aquarium with a
number of these fish as inmates is sure to be a scene of continuous
battle and slaughter unless they have plenty of room; and of course
it will not be safe to introduce with them any other small and
harmless species. Again, if it is desired to watch the construction
of the nest and the parental care of the male, it will not do to have
more than one or two pairs in the same vessel unless it is very large
and well supplied with weeds, the use of the weeds being not only
for the aération of the water and the supply of materials for the
construction of the nest, but also to serve as a kind of barrier
between the sacred areas of the jealous parents.

We have already said that the Stickleback is not particular as
to its food—that it will devour almost any living creature, provided
it can swallow it, and herein lies another consideration to be borne
in mind when introducing this fish into aquaria or ponds in which
we intend to breed and rear other species; for the Stickleback will
eat any spawn that comes in its way, and the newly hatched fry
from the eggs that escape its notice stand very little chance of
attaining any size in its company.

The only other freshwater fish we need notice is the Common

Sullhead or Miller’s Thumb (Cottws gobio), which belongs to the
same family as the marine Gurnard. This fish is not by any means

FISHES FOR THE AQUARIUM 359

ugly, though, as one would surmise from the first popular title, its
head is rather out of proportion. The origin of the second of these
names is not far to seek, for the head is flat and broad, somewhat
resembling the shape of a miller’s thumb, flattened by its frequent
application to the meal-spout to test the quality of the flour; and
as this little fish is very partial to the small rapid and stony streams
that so often drain millponds, those familiar with the mill and its
neighbourhood have not failed to note the likeness just mentioned.

Fic. 288.—Tue Buiiyeap (Cottus gobio)

Although the habits of the Bullhead are interesting, it does not
often display itself in the aquarium ; for it spends nearly the whole
of its time in hiding under stones, and seldom shows itself except
when it darts after a passing insect, crustacean, or other small
creature on which it preys. In the evening it will exercise itself,
but even then its excursions are short and almost entirely confined
to a sort of shuffling movement from one hiding place to another.

The Miller’s Thumb may be easily taken by hand in shallow
water, but the best way to secure it is to scrape up the bottom of
the stream it inhabits with a strong net, when a mixture of stones,
gravel, and fish will generally be obtained.

The fish may be readily identified by means of our illustration
and the characteristics mentioned above, but I will also call atten-
tion to the bony spines at the sides of the head, and the strongly
developed pectoral fins which assist the creature as it creeps, as it
were, along the bottom.

360 LIFE IN PONDS AND STREAMS

CHAPTER XII
AMPHIBIANS

We have yet another class of animals to consider in connection with
freshwater life, and this is the Amphibia, which includes Frogs,
Toads, and Newts.

The word Amphibia signifies ‘ double life,’ and under this head
we place those creatures that spend a portion only of their existence
in water. But, before we go any further, it will be necessary to give
a word of explanation in order that we may learn to use the above
term in its proper restricted sense.

We have already studied many creatures that are only tempo-
rarily aquatic. Thus we have seen that certain spiders are almost
equally at home both in water and on land, and that numerous
insects are truly aquatic only during their earlier stages, and that
some of these, in their perfect forms, pass freely from ponds and
streams into the air or on to the land. We have also several mam-
mals, such as otters, water rats, beavers, and seals, that are often
spoken of as amphibious on account of their partially aquatic habits.
Many birds, too, have very marked appreciation for either fresh or salt
water, some being expert swimmers and divers, while others prefer
the shallow waters of marshesandfens. Yet none of these creatures
belong to the Amphibia. This class contains only those vertebrates
that are specially provided with breathing organs which render them
particularly adapted for direct respiration—that is, for acquiring the
necessary air supply direct from the atmosphere; and also for the
absorption of air that is dissolved in the water in which they are at
times submerged. In other words, the members of the Amphibia,
during at least a part of their existence, possess gills which enable
them to breathe under water just as fishes do; and also, in the
adult stage, possess lungs that permit the direct absorption of oxygen
from atmospheric air inhaled after the manner of the higher animals
—ourselves included.

AMPHIBIANS 361

The true amphibians are cold-blooded creatures which are de-
veloped from eggs, and exhibit, in their earlier stages, a rather close
relationship to the fishes. Only a few of them can be described as
large animals, and of all the five classes of the Vertebrates, the
Amphibia contains the fewest species.

The reader has probably observed that in some of the older works
on natural history the animals which we now call Amphibians are
included, with snakes, lizards, and tortoises, under the head of
Reptilia or Reptiles; but, although they resemble the latter in
several important features, they differ materially in that they
undergo remarkable changes as they pass from their early to their
adult stage—changes which are so striking as to justify the forma-
tion of a separate class for the reception of frogs, toads, newts, and
their allies.

Let us take a general view of this interesting class, tracing the
Amphibian through those metamorphoses which may be regarded
as the most important characteristic of the group.

When the young one first emerges from the egg it is a little
dark-coloured limbless creature with a large ‘head’ (really head
and body together) and a long tail. In this state it is spoken of as
the tadpole or larva; and from this period it undergoes a regular
series of metamorphoses till the adult form is attained. These
changes at once remind us of the more familiar metamorphoses of
insects ; but while the latter frequently pass through an intermediate
passive and dormant stage known as pupa or chrysalis, the Amphi-
bian is very active in all its various states, and it exhibits no ap-
parently sudden transformations like those so commonly observed
in insect life.

Although somewhat fishlike in form, the young Amphibian has
generally no covering of scales, but its skin is smooth and very soft,
the outer layer being very little developed. It also differs from
fishes in having no true fins, but it frequently possesses a substitute
for these organs in the form of membranous fringes which, in some
species, disappear before the adult stage is reached, and in others
are persistent throughout the creature’s existence. It further re-
sembles a fish in the possession of membranous sacs which contain
air, corresponding with the air bladder or swimming-bladder of the
latter, by which the specific gravity of the body may be slightly
altered to suit varying circumstances. At this stage, too, its heart
consists of only two chambers—an auricle and a ventricle—in

362 LIFE IN PONDS AND STREAMS —

which feature it displays yet another proof of its cousinship to the
finny tribe.

The breathing organs of the tadpole consist of external gills, by
which oxygen is absorbed from the water in which it now lives.
The digestive tube is long and coiled spirally.

As the tadpole gradually develops into the adult stage of its
particular species, various changes, both in external form and in
internal structure, are progressing simul-
taneously. The air sacs become larger,
and a rich network of blood-vessels is
developed within their substance, till at
last they become a pair of lungs by which
the creature is enabled to breathe out of
the water. At the same time, in some
species, the gills gradually disappear, so
that the mature animal can no longer
breathe while under the water; but in

Fic. 289.—Tue Youne Tap™
POLE OF THE ComMMON FROG

(Rana temporaria), EN- Fig. 290. —THREE-CHAMBERED
LARGED ; SHOWING THE EXx- Heart oF THE ADULT FROG, ENLARGED
TERNAL GILLS a, auricles ; v, ventricles

others the gills are retained throughout the whole existence. In
both cases, however, the creature is not entirely dependent on
these special respiratory organs for its necessary supply of air, for
the skin is always soft and moist, and capable of absorbing air,
either direct or from the water in which the creature lives or rests.

While these changes are progressing, the two-chambered heart
of the tadpole develops a second auricle on the left side for the
reception of the aérated blood from the breathing organs, the right

AMPHIBIANS 363

auricle receiving the darker blood that has just completed its circu-
lation in the various parts of the body. The digestive tube gradually
becomes proportionately shorter and less
coiled. In most species, too, two pairs of
limbs appear, and in some cases the tail
is gradually absorbed, while in others it
persists throughout the whole lifetime,
and becomes a useful and sometimes
very ornamental appendage.

In the higher Amphibia the skeleton
of the adult is remarkably well developed.
The vertebre form moveable ball-and-
socket joints, but the ribs are either small
or entirely wanting.

One more striking feature of the
Amphibians is worthy of notice. The
corpuscles or blood-cells are remarkably
large. In one species-—the blind Proteus
that inhabits the dark caves of Carinthia—
these cells, which are oval in form, mea-
sure as much as z45th of an inch in
length.

The class Amphibia is divided into
three orders, as follows:

1. Gymnophiona—limbless creatures
resembling earthworms in form and \
habits. Their bodies are ringed like those
of worms, but the skin is usually covered
with scales. They live in burrows in the

Fic. 291.—Tue Unper
SIDE OF THE TADPOLE
OF THE FROG, sHow-

ground, and their eyes are rudimentary. ING THE COILED Dt1-

This order contains only a few species, sucnkion TUBE, os

: UCKERS, THE In-

and these all inhabit tropical countries. bai Giant ee
. VIVN Ada 4Lid, AX

2. Urodela—the members of which THE REsPrrRaToRY
possess limbs and a permanent tail. This APERTURE, ENLARGED

order is divided into two sections—

(a) Those in which the gills of the tadpole stage are retained
throughout the whole or greater part of their life, and in which
lungs are gradually developed as the adult stage is reached. This
section has no British representative, but includes the Proteus
already mentioned, also the two-limbed Sirens or ‘Mud Eels’ of
Carolina, and the four-limbed Azolotl of Mexico.

364 —O LIFE IN PONDS AND STREAMS

(b) The second section, in which the gills disappear as the lungs ©

are developing, is far more interesting to us, since it contains the
Newts and Salamanders that abound in our ponds and ditches.

3. The third order—Anwra—includes all those Amphibians that
are without tails in the adult stage, and is well represented by our
Frogs and Toads.

The British Amphibians number only seven species, which may
be classified as follows:

Class AMPHIBIA.
Order URODELA or CAUDATA.
Family SALAMANDRIDA. :
1. Molge cristata (Triton cristatus)—The Great Warty
Newt.
2. Molge vulgaris (Lophinus punctatus)—The Common
Smooth Newt.
3. Molge palmata (Lophinus palmatus)—The Palmate
Newt.
Order ANURA or ECAUDATA.
Family RANIDAS.
4. Rana temporaria—The Common Frog.
5. Rana esculenta—The Edible Frog.
Family BUFONIDA.
6. Bufo vulgaris--The Common Toad.
7. Bufo calamita—The Natterjack Toad.

Tue Common FroG (Rana temporaria)
(Plate VII, fig. 1)

The general plan of this book has been to work wp the scale of
life, from the lower to the higher forms; and, to be consistent in
the present chapter, we should study the Newts before the Frogs.
But the Common Frog is generally so much better known than the
other British Amphibians, and forms such a splendid type of its
class, that I am tempted to make one trifling deviation from the
plan in order that we may study the species in what seems to be
a more convenient order.

In the spring-time, usually about the beginning of March, but
sometimes earlier or later according to the forwardness or back-
wardness of the season, Frogs may be seen in ponds and ditches,

§

PLATE VII.

D ’ 5
anicisson or

», London, del. ad. Nat. e Chromeouls

i

AMPHIBIANS 365

where they have congregated for the purpose of depositing their
eggs; and towards the middle or end of the same month large
masses of a jellylike substance, containing numerous black spots,
may be seen floating on the water, sometimes in such quantities
as to almost completely cover the surface.

These eggs are laid in one continuous string, the black and white

Fic. 292..-Ea6s or THE FROG, JusT LAID

embryos being all held together by the gelatinous envelopes. At
first the gelatinous envelopes are not very thick, and the newly laid
eggs, which are only one-sixteenth of an inch in diameter, lie on

Fic. 293.--Eaas or THE FroG, A FEW HOURS AFTER LAYING

the bottom of the pond; but in a very short time the envelopes
swell out till the diameter of each egg is from a quarter to three-
eighths of an inch.

After a few hours the embryo or yolk begins to divide into seg-
ments or cells—a process which may be easily observed under the
microscope. At first a depression divides it into halves, and shortly
after’another one, at right angles to the first, forms four divisions.
Next follows a third depression that runs transversely round the
yolk, nearer one ‘ pole’ (crossing point of the first two depressions)
than the other. Then there appear other longitudinal and trans-

366 LIFE IN PONDS AND STREAMS
verse divisions, till the yolk is at last broken up into a mulberry-like :
mass of cells.

While these changes are progressing, a cavity begins to form,
and around this the cells soon arrange themselves in layers, those

Fic. 294._-Various Sraces or THE PRocESS OF THE SEGMENTATION
OF THE YOLK, MAGNIFIED

of the upper part becoming very dark in colour, and more regular

than the others.
Soon the darker regular cells, which have become much smaller

Fic. 295.—Sxrction THROUGH A F'RoG’s EGG, SHOWING THE
INTERNAL ARRANGEMENT OF THE CELLS, MAGNIFIED

than the others by repeated divisions, spread over the whole of the
surface ; and two distinct strata are formed, the outer one of which
gives rise to the external skin and the brain and spinal cord, while
the inner layer is that which forms the delicate lining of the food

AMPHIBIANS 367

passage. Between these two layers are the cells from which all the

other parts of the body are evolved.
A groove is now formed on the upper surface of the embryo, the

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Fic. 296.—A SEcTION THROUGH THE EMBRYO AT A LATER STAGE,
SHOWING THE THREE LayeRS Or CELLS, MAGNIFIED
1, the primitive greove ; 2, the notochord, representing the future backbone

sides of which eventually unite so as to form a canal or tube which
is destined to contain the brain and spinal cord. And so the
gradual development proceeds till, at the end of twelve or fourteen
days, the little embryo has become a fishlike tadpole, ready to
make its way out of the gelatinous covering and start in life on its

own account. .
But although these interesting changes are to be observed only

Fic. 297.—TuHer DEVELOPMENT OF THE FROG EMBRYO AS OBSERVED
WITH THE UNAIDED EYE, NATURAL SIZE

by the aid of a microscope, yet there are outward signs of develop-
ment that are easily seen with the naked eye. About a week after
the eggs have been laid, the dark embryo is no longer spherical,
but oval in form ; and two or three days later it begins to exhibit a
well-marked division into head, body, and tail. At this stage, as it

368 LIFE IN PONDS AND STREAMS

lies coiled up within its transparent envelope, it looks more like a
little fish than a frog.

Now two pairs of little branched tufts appear at the sides of the
neck, followed, after a brief period, by a third pair. These are the
external gills by which the creature is to obtain its supply of air
when it is free.

Fic. 298.—Tue Youna TapPpoLE SHORTLY BEFORE
HATCHING, MAGNIFIED

About two weeks have now passed since the eggs were laid, and
the tadpoles may be seen wriggling about in a restless manner
within their gelatinous spheres. Then, one by one, and in rapid
succession, the numerous members of the same brood break loose
through their weak prison walls, and, for
a time, play round about their vacated
homes, sporting and resting alternately.
They very soon show their gregarious
tendencies by collecting in dense clusters
on the surface of pondweeds or any con-
venient objects, holding on by a pair of
suckers on the under side of the head
(fig. 299). These clusters at once become
the scenes of an almost constant turmoil.
So strongly marked is their desire to put
their heads together, that each one who
Fic. 299.—A Geran or is so unfortunate as to be for a moment

very vouna Tappones on the outer edge of the cluster, immedi-

ately loosens its hold, and struggles for
a place nearer the centre, wedging itself in between its companions
with a smart wriggling of its tiny body, and almost invariably dis-
placing one or two, thus compelling them to do as it had done.
And so there seems to be an almost perpetual struggle for a good
position.
Now, if all these vigorous efforts were made in order to relieve
the pangs of hunger or to secure some tasty morsel, no further
explanation would be necessary ; but the young tadpoles indulge in

AMPHIBIANS 369

this seemingly selfish process of turning their neighbours out of
doors when no food is at hand ; nay, more, even before their mouths
are formed! We can therefore ascribe such behaviour only to an
instinctive gregariousness.

During the first few days of the tadpole’s life it does not, nor
cannot, eat any food, but is sustained by the remains of the ‘ food-
yolk’ within its own body, on which it thrived before leaving the
egg, and whichis still unexhausted at the time of its exit. But now
the mouth appears; bordered by lips with horny projections, and
armed with a pair of horny jaws.

It now commences to feed vigorously on a vegetable diet,
devouring conferve and other low forms of plant life, and rapidly
increases in size.

Fic. 300.—TappoLes IN VARIOUS STAGES, NATURAL SIZE

linportant structural changes accompany this rapid growth.
The food canal, which was previously short and wide, speedily
develops into a long coiled tube (fig. 291), and the glands (liver and
pancreas) which secrete the digestive fluids soon enlarge and become
active.

At the same time the respiratory organs are undergoing remark-
able modifications. Four little slitlike apertures, called the gill
clefts, are formed on each side of the neck. These communicate
with a cavity at the back of the mouth, and their edges, turning
inwards, develop into internal gills. While these changes are pro-
gressing, the external gills gradually become absorbed, and a flap
of skin grows backward from each side of the head, covering the
gill clefts, and finally enclosing them in a cavity called the gill
chamber. Then the fold of skin (called the operculum or gill cover)

BB

370 LIFE IN PONDS AND STREAMS

on the right side unites with the outer covering of the body,
completely shutting in the gills, while that of the left side only
partially closes, leaving an opening (fig. 291)
by which the water taken in at the mouth for
respiratory purposes can find its exit from
the gill-slits on both sides. :

The tadpole is now about a month old,
and has reached a total length of about one
inch. Its body is round, and its tail long
and supplied with broad membranous fringes
above and below. It swims rapidly by an
undulatory movement of its powerful tail,
and no longer uses its suckers ; m fact these
organs, like the other temporary appendages,
have so degenerated as to become useless.

The future limbs next begin to appear.
The first sign of these is a pair of small
projections at the base of the tail. These
gradually develop. A few weeks later they
are well formed, the toes appearing after the
\ legs have exhibited a distinct division into

joints. The forelimbs appear later, though
ae »- they are actually formed at the same time
ae hs eon as the hind pair, for they are at first hidden
orDrveLopment— beneath the folds of skin that cover the gill
THE FRONT PAIR ¢lefts. The right one breaks through this
BEING STIL CON- skin, while the left forces its way through
CEALED UNDER THE ; ; :
GILL COVERS the opening on that side for the exit of the
water that circulates in the gill chambers.
3ut while the four limbs are developing, a number of interesting
modifications are in progress in various parts of the tadpole’s body.
After a short period of less activity, the whole of the outer skin is
shed, together with the horny jaws, and the eyes are for the first
time fully exposed. ‘The mouth, which was before round and small,
now becomes gradually wider, and the tongue very much larger.
The lungs are developing, and for a time the creature breathes both
by lungs and gills, occasionally coming to the surface for a small
supply of air. ‘Then the gills entirely disappear and the clefts close
up, so that respiration is carried on by the lungs only. The diges-
tive organs also take part in the wonderful transformation. The
stomach and digestive glands become much larger, while the intes-

Fic. 301.— Tue Tap-

AMPHIBIANS 371

tinal tube, which we observed to be long and coiled in the earlier
stage, now shortens considerably, at the same time becoming
narrower. The diet is also changed in accordance with the new
capacities of the digestive apparatus, the former vegetable food being
entirely discarded for an animal regimen.

Finally the hind limbs grow very long; the foot becomes long,
slender, and webbed ; the tail, which has for some time been gra-
dually diminishing, is completely absorbed; and the creature, now
a perfect frog, wanders from its pond or ditch among the moist
grass, searching for worms and insects, and occasionally returning
to the water in dry weather to moisten its delicate skin.

Fic. 302.—Youne Frocs

Now that we have traced the frog through its metamor-
phoses, let us proceed to learn something of the more interesting
characteristics of the perfect form, and observe some of its
movements.

In the first place let me say that frogs are almost always very
easily obtained, and very easily reared in all their stages, so that
any one who desires to study them cannot do better than keep them
as pets either in the garden or in some prepared home. If your
garden is surrounded by a wall such as would prevent the escape
of your captives, then, with the expenditure of only a little time
and labour, you can keep your frogs under perfectly natural con-
ditions, allowing them all the comforts and freedom of the wild
state.

If this is to be your plan you must prepare a pond similar to
that recommended on page 85, but see that the edges are such
that the frogs can easily walk out of the water; also have your

BB2

372 LIFE IN PONDS AND STREAMS

rockery so loosely piled that the amphibious creatures will have
no difficulty in finding a nook in which to hide during the day-
time.

Although such an arrangement is certainly the best you can
possibly have for the frogs themselves (and I need hardly say that
it answers equally well for newts and toads), yet it is not always
the most convenient for the naturalist ; for the creatures have such
a clever way of concealing themselves during the daytime, and
especially in dry weather, that they are not always to be found
when wanted for observations. But even when it is necessary to
keep a few specimens in closer confinement for the observation of
their habits, it is still a good plan to have a reserve in a wild or
semi-wild state close at hand. It is wellto remember, too, that the
amphibians are perfectly harmless to fishes, and that both may
consequently be reared in the same pond as far as the safety of the
latter is concerned; but many of our freshwater fishes readily
devour tadpoles, so that, unless you start with a good number of
the amphibious larve, all will disappear before they have reached
an age at which they can protect themselves by leaving the
water.

Tadpoles should have plenty of room, and if a suitable pond

cannot be provided, let them have a large tub of water, well supplied’

with aquatic plants ; and then, when they give evidence of the final
change in the respiratory organs by coming to the surface to breathe,
they must be immediately removed to a pond, or be provided with
some means by which they can easily quit the water when their
truly aquatic life is at an end.

When the metamorphoses are over—that is, when the young
frogs have assumed the form and habits of the adult—they may be
kept in any kind of case or house, providing they have a small
supply of water, changed at frequent intervals, a few piled stones
for shelter, and a layer of turf or growing moss. They may be
made very comfortable in a greenhouse, fern case, or any form of
large glass vivarium, providing these conditions are maintained ;
but if thus confined they must be well supplied with food—worms,
grubs, beetles, Xe.

Frogs and toads are often kept in greenhouses for the sole pur-
pose of keeping down the insects that are so destructive to plants,
and it is too often assumed that the creatures so confined have
plenty to eat. It must be remembered, however, that the floor of
a greenhouse is often composed of a material through which worms

‘
fi
A
:

AMPHIBIANS 373

cannot burrow, and that the florist’s plants are frequently placed
in such a position that the frogs and toads cannot reach the insects
that feed on their leaves. Under these circumstances it is as
much the duty of the owner to feed his frogs as to water his
plants.

Now let us note some of the more interesting points in the
structure and habits of frogs that have not been previously mentioned
in our account of their metamorphoses.

Look at its skeleton—a splendid type of the internal framework
of the vertebrate animals. The backbone, with which all the other
bones are directly or in-
directly connected, con-
sists of nine ringlike
vertebre, all jointed to-
gether in such a manner
as to form a flexible
column, and behind these
a long narrow bone—the
uwrostyle—extending back-
wards almost to the hin-
dermost extremity of the
- long bones of the hip or
pelvis. The skull, it will
be observed, is very wide,
with only a small tubular
cavity in the middle to
contain the brain; and Fic. 303.—THe SKELETON or THE FROG
the lower jaw is so exten-
sive as to admit of a very wide gape. Teeth exist in the upper jaw
and on the palate or roof of the mouth, there being none on the
lower jaw. ‘They are very small—perfectly useless for mastication
or chewing—but are provided with sharp, hooked crowns that
enable the creature to hold its larger victims secure while they
are being gradually devoured alive.

The shoulder girdle surrounds the front portion of the vertebral
column, but is connected with it only by muscles and ligaments ; so
that in a prepared skeleton it is, together with the arms and breast-
bone, quite disconnected from the rest of the bones.

The arms are attached to the shoulder by means of a ball-and-
socket joint, the rounded head at the top of the upper arm fitting
into a cavity of the girdle. The little bones of the wrist and hand

374 LIFE IN.PONDS AND STREAMS

are beautifully formed and jointed, and correspond very closely with
our own in structure and arrangement.

When a frog is at rest, its back often exhibits quite a prominent
hump near the middle. This is not due to any sudden bend in
the backbone itself, for this is always very nearly straight, but is
caused by the oblique arrangement of the long bones of the hip.
The fore extremities of the latter are jointed to two large projec-
tions which extend upwards and outwards from the ninth vertebra,
and from these the hip bones curve downwards to the hinder end
of the body.

The structure of the legs is very similar to that of the arms, but
the former are much longer, and, moved as they are by very
powerful muscles, they enable the frog to take prodigious leaps on
land, and to swim with considerable speed in the water. The
length of the foot is remarkable, and is due not only to the presence
of very long bones in the toes and what we should in our own case
term the instep, but the heel and ankle bones are also considerably
elongated.

There is one other peculiarity of importance in the skeleton of
the frog, viz. the absence of ribs, so that all the internal organs that
lie behind the shoulder girdle are protected by soft structures only
except where covered hy the backbone and pelvis.

Every one who is interested in the internal structure of the frog
should prepare for himself a complete skeleton. By so doing he
will certainly learn much, and the specimen will always be valuable
as a work of reference as well as an object of beauty. The process
is simple, requiring patience rather than skill.

Open the abdomen of a dead frog with a penknife or a pair of
sharp-pointed scissors. Remove all the internal organs, and cut
away all the skin and flesh. Thus in about half an hour or so you
will get the bones comparatively cleared. Of course you have to be
careful not to cut any of the bones, also that you do not in any way
injure the cartilages. The latter, in fact, are to be preserved with
the harder parts of the framework. The ligaments also, which bind
the bones together at their joints, should be left intact.

When the skeleton has been roughly cleared as above directed,
it should be soaked for a time in hot water. This will soften the
small quantity of flesh that remains, and then the final cleaning can
be performed with the aid of a soft brush, using a small pair of
scissors occasionally to cut off the projecting tendons,

a

AMPHIBIANS. B75

The shoulder girdle, together with the arms, will become de-
tached. The lower jaw also will probably become disconnected.
But these, and other parts that may be separated during the final
cleaning, can easily be fixed together again by means of a little
coaguline after the whole is dry.

When the clearing operation is all over, transfer the skeleton to
a sheet of cork, and, after supporting it in some attitude natural to
the living creature by means of pins and pieces of cork, set it aside
to dry.

The exigencies of space will not permit of a detailed descrip-
tion of the arrangement, structure, and functions of the various
internal organs of the Frog, so we shall have to confine our observa-
tions to the more obvious features that are likely to attract the
attention of young observers.

Let us watch the inmates of our vivarium as they rest in their
shallow little pool, with perhaps only so much of the bodies above
the surface as is necessary to expose their prominent eyes and
nostrils to the air. Or it may be that we shall have to look for
them in a cosy little corner that has been hollowed out into a
comfortable cradle by a vigorous scratching and shuffling of their
long hind legs, where they lie hidden from view under a layer of
soft green moss.

The smooth soft skin, though very variable in colour, is always
more or less mottled with a darker tint on the upper surface, and
these darker markings always include a patch on each side extend-
ing from the eye to the shoulder.

The ground colour varies in different individuals, and also in the
same creatures at different times. Sometimes it is a very pale
yellow, on which the darker markings stand out boldly, giving a
very pretty contrast; but in other cases it is very dark—almost a
black, on which the mottlings are hardly visible. I have at the
present time, among my pets, frogs exhibiting remarkable extremes
in this respect, including both the lightest and the darkest ground
colours I have ever observed in the species. And it is noteworthy
that all the dark specimens were taken in or near ponds situated in
rather dark shady corners, with beds of black mud, and surrounded
by a very dark soil; while the very light ones were all taken in
open grass lands with a light yellow clay soil. Thus in both cases
the creatures were undoubtedly protected more or less by their
resemblance to the surrounding colours. It must be observed,

376 LIFE IN PONDS AND STREAMS

however, that the colours of any one individual are by no means
permanent, the same frog often appearing in new tints several times
during the course of a few days.

Just behind the eye, in the middle of the dark patch mentioned
above, is a dark circular membrane, supported by a firm ring that
surrounds it. This is the tympanic mem-
brane of the frog’s ear, by means of which
the vibrations of the air are transmitted to
the internal ear.

As we watch our frogs we observe the
floor of the mouth of each one perpetually
rising and falling, and the nostrils alternately
opening and closing. These movements are
Fic. 304.—Hrap or connected with respiration—a function that is

nici Bist hala he performed in the case of the frog in a very

different manner from the same function in

ourselves. A frog cannot breathe with its mouth open; and it

necessarily follows that death from suffocation must result if its
mouth be kept open for a considerable time.

The breathing of the frog through the agency of the lungs is
carried on as follows: The floor of the mouth is depressed, thus
making the cavity of the mouth larger, while the nostrils are open.
In this way air is made to enter the mouth, through the nostrils,
just in the same manner that it is made to enter the cavity of a pair
of bellows or a force-pump through the valve. The floor of the
mouth is then forcibly raised by muscular action while the nostrils
are closed, so that the air, thus driven from the mouth, and having
no other outlet, is forced into the lungs—an action which also finds
its counterpart in the bellows and force-pump. The expulsion of
this air from the lungs—expiration—is then brought about by a
contraction of the muscles of the flank, which cause the internal
organs to exert a pressure on the lungs, and is assisted by the con-
traction of muscular fibres that exist in the walls‘of the lungs
themselves.

In our own case a cessation of the regular movements of respira-
tion would cause death in a very few minutes; but such would not
be the result in the case of a frog. We are entirely dependent on
the lungs for the aération of the blood, but the frog is provided with
a second means of respiration in its soft, moist, permeable skin,
through which air readily passes into the dense network of minute
blood-vessels that lie immediately beneath. Hence it is probable

|

—_ =

Se ee |

AMPHIBIANS B77

that a frog would continue to live for some considerable time after
the complete cessation of its pulmonary respiration.

- While speaking of respiration it may be well to call attention
to the cruelty so often unwittingly practised by inexperienced aqua-
rium owners of keeping frogs in an ordinary aquarium where the
creatures have no resting place close to the surface of the water.
In such a case the poor frogs never get any perfect bodily rest. If
they succeed in finding a hiding place at the bottom of the aquarium
they are compelled to rise at frequent intervals for the necessary
supply of air; but they will more often allow themselves to float on
the surface, perpetually making vain attempts to get a foothold
above the water, and frequently struggling to keep their nostrils
in the air. Frogs are not aquatic creatures, and will never live long
in an ordinary aquarium. On the other hand, they should always
have a small supply of clean water in which they can have an
occasional bath to keep the skin moist in order that it may perform
its respiratory function. Failing this supply, unless they are pro-
vided with a hiding place that is perpetually damp, the skin will
become dry and hard, and death speedily follow. If the vivarium
is kept indoors throughout the winter, and so protected from the
low temperatures to which frogs are exposed in their wild state,
then they will not hibernate, but will make their appearance night
after night, except perhaps in very severe weather, and take a
ramble round their little home, occasionally indulging in a small
meal if their wants in this direction have been studied. Under
these circumstances, too, they retain their amphibious character-
istics all through the cold season, sometimes remaining hidden for
days together, but occasionally taking to the water, and resting for
longer or shorter periods almost entirely submerged.

As we watch them at this season of the year we observe that
their eyes are sometimes closed, the prominent eyeballs having
been retracted, and the lids drawn completely over them. But let
us select a wide-awake pet to see how these movements are brought
about. We touch its prominent visual organ gently with the finger.
At once the ball is pulled in by muscular contraction, and at the
same time the upper lid descends, but only a little way, and the
lower one, which is far more mobile, rises to meet it. But as soon
as the finger is removed the lids are withdrawn, and the retractile
ball again resumes its prominent position.

The croaking of the Frog is produced by the vibration of two
vocal ligaments which correspond with the so-called vocal cords in

A fe.

378 LIFE IN PONDS AND STREAMS

our own bodies. These sounds are often described as anything but
musical, but for my own part I regard the concert given by a
number of these amphibians during the still hours of the evening
as decidedly pleasant. During the hibernating period frogs are as
silent as they are still, but our indoor pets treat us to an occasional
note at this dull season. This, however, is not a spontaneous
serenade such as that with which the creatures so lavishly greet
one another during the breeding season in early spring, but only an
expression of resentment at some unwarrantable intrusion. Thus
one of the inmates, making a tour of inspection round its case, with
of course the usual attempts to walk straight through the clear
glass, and paying not the slightest respect to any of its fellows, walks
deliberately over the back of one, and then perches itself on the
top of another as if to get a better view of the surroundings. In
either case a croak of dissatisfaction may be emitted by the creature
so unceremoniously treated, but the sound is generally much
shorter and far less musical than the love songs of a spring
evening.

But there is another and very different sound produced by the
frog—a rather sharp and piercing cry, much resembling that of a
young child in agony, and emitted, as far as my experience goes,
only when the creature is in great terror. I first heard this peculiar
cry proceeding from near the bank of a brook, at the bottom of a
meadow ; and, on hastily approaching the spot, saw a full-grown
snake with the hind leg of a struggling frog fast in its jaws; and
since that time I have on several occasions heard the same sound
produced by frogs similarly surprised; and if the power and fre-
quency of these cries may be taken as a measure of the agony of
the creatures concerned, it is certain that the frog is far more
terrified by the painless grasp of a snake’s jaws than by the clutch
of a human monster.

We have already said that frogs feed freely during the warmer
months, and that they do not as a rule take any food in the
winter, so that our observations on their capacity for ‘taking
nourishment and their methods of capturing and disposing of their
prey should be taken in the spring and summer. At these seasons
we should supply them liberally with their favourite viands—worms,
caterpillars and other grubs, flies, moths, beetles, &e.

Here is a fly, crawling up the glass of the vivarium. Let us
watch what will happen. One of our frogs immediately prepares
for action, ‘The fore part of its body is raised by its outstretched

ee ee ee ee a a ae

; AMPHIBIANS 379

arms ; and, with elevated head, it keeps its eyes steadily fixed on
the unwary insect, as yet safely out of reach. As the fly crawls
round toward the corner of the case, the watchful frog now and
again takes a single quick step in the direction of its prey; and,
when at last the insect comes within range, with a vigorous leap it
makes a dash against the glass. The frog of course falls to the
bottom again, but, like a cat, almost invariably settles on its feet.
And as for the fly, it disappeared so suddenly that we are doubtful
whether it is captured or has escaped, until a muscular movement
in the frog’s forequarters tells us that the act of swallowing is in
progress.

So rapid are the motions of the frog that we have some difficulty
in deciding how the feat of capturing its prey is accomplished ;
but a close and careful observation of the act will show us that its
tongue is thrust out with lightning-like rapidity as the creature
takes the leap, that the fly is held securely by the viscid saliva
with which this organ is coated, and that the equally rapid retrac-
tion of the tongue causes the insect to be safely lodged in the
capacious mouth, which immediately closes and effectually prevents
the escape of the victim.

Let us now examine this efficient prehensile organ to see in
what way it is peculiarly adapted for such an important function.
After some little difficulty we suc-
ceed in opening our pet’s mouth,
and observe that the tongue is fixed
to the lower jaw in the very front
of the mouth, and that its free
end, which is divided into two lobes
by a depression in the middle, is
directed backward. Thus it is that
the owner is enabled to shoot it
forward some considerable distance ;
so far, indeed, that when the frog fy. 305.—Tonave or a Froa
captures an insect, as it often does,
without taking a leap at all, the latter is seen to suddenly vanish
while the front. portion of the frog’s head does not approach it
within a considerable fraction of an inch.

When a frog attacks a large worm or grub, the mode of
procedure is very different. After approaching its prey to within
an inch or so, its head is suddenly thrust forward, the defenceless
creature is seized at any convenient point by the frog’s jaws and

580 LIFE IN PONDS AND STREAMS

then, without the slightest pause, a series of the most grotesque
movements follows. The frog seems to struggle unnecessarily.
Its forelegs, now the right and then the left, are used to push the
projecting portions of the poor victim into its mouth. A number
of vigorous gulps are made, the whole of the body apparently taking
part in the muscular movements, and the prominent eyeballs are
each time pulled within their sockets and closed, as if a momentary
darkness served to intensify the sensation of the palate. But all
this lasts for only a short time, and the worm or grub, still alive
and practically uninjured, finds itself safely lodged in a com-
paratively small digestive pouch, where it is probably slowly killed
by the exclusion of air and the action of digestive fluids.

Fic. 306.—BuLoop-ckELus oF Fic. 307.—CrrcuLATION OF
THE FRoG _ Buoop 1n THE WEB OF A
Ja
a, red corpuscle ; b, colourless Froa’s Foor

corpuscle

We have already referred to the comparatively large size of the
corpuscles or blood-cells of Amphibians. These in the frog are oval in
form, and one-thousandth of an inch in length, or about three times
the size of the corpuscles in our own blood. This remark applies to
the red corpuscles of the frog; but in addition to these there are
others which are colourless, and these are smaller, and much fewer
in number.

A microscope that will magnify up to one hundred diameters is
sufficiently powerful to show these blood-cells well; and as the web
between the frog’s toes is very thin and transparent, there is no
difficulty in observing the circulation of the blood in the living
animal. The corpuscles may be seen passing with the current of
colourless liquid from the smaller arteries into the capillaries, the

AMPHIBIANS 381

walls of which are so very thin as to be almost invisible. The white
cells, which may be seen continually changing in form, generally
creep slowly along the walls of the vessels, while the red ones move
more rapidly in the centre of the stream. It will be observed also that
the latter are decidedly elastic ; for when they reach an angle formed
by the junction of two small vessels, they are often compressed
by the slight pressure to which they are subjected, but resume
their normal form as soon as the pressure ceases.

THE EprIsBLe FrRoG (Rana esculenta)
. (Plate VII, fig. 2)

It is extremely doubtful whether this is really a British species,
though it is to be found in many localities in the eastern and other
counties. It is well known that about fifty years ago many hundreds
of these frogs, as well as large quantities of spawn, were imported
into this country from France and Belgium and deposited in the
Fens; and there seems to be no record of the presence of the species
in the British Isles previous to this time.

Fisculenta is larger than Temporaria, and is generally of a green-
ish tint, though sometimes of a rather rich reddish brown. It is
conspicuously marked with darker tints, and may be readily distin-
guished by a pale line down the middle of the back. The dark
patch which extends from the eye to the shoulder in Temporaria is
absent in the edible species, and the latter, though very variable in
colour, is generally much
handsomer. The _ space
between the eyes is usually
convex in the common
frog, and concave in the
edible species, and the
distance between the eyes
is much less in the latter
than in the former; the

tympanum, which is com- 4 : rep g -
. . ‘rg. 308.—TuHE Uprer SIDE or THE HEAD
paratively small in the ,
or THE Marte Rana esculenta, sHow-

case of Temporaria, is as ING THE VocaL Sacs INFLATED
large as the eye in Hscu-
lenta. The croak of the edible frog is also louder and much more
musical than that of Temporaria.
The male Esculenta is provided with a pair of large pouches,

582 LIFE IN PONDS AND STREAMS

communicating with the cavity of the mouth ; and situated one on
each side of the head, just behind the angle of the jaw. These are
known as the vocal sacs, and are dilated to a spherical form when
the animal is croaking, being then inflated with air.

These two British frogs so closely resemble each other in general
structure that the brief description given of the common species
applies equally well to both ; and the same remark holds good con-
cerning the metamorphoses through which they pass in their earlier
days. But the edible frog is more strictly aquatic than the common
species, and seems to be almost as partial to running streams as it
istoponds. It does not wander so far from the water as its relative,
and is consequently not always so easily caught, being generally able
to hide itself immediately by taking a plunge into a pond or stream
close at hand.

This greater partiality for water is exhibited by the edible frog
when in captivity. During the winter season I have generally
found this creature lying in the shallow pool of water that was pro-
vided in the vivarium after all the frogs of the common species had
completely hidden themselves beneath the moss and stones. And,
generally speaking, it leaves the water only during very severe
weather. Also, it does not seem to be so careful concerning the
ordinary comforts of life as its smaller companions ; for, while the
latter invariably seek out or scoop out for themselves snug little
beds where they can sleep in quiet seclusion, perfectly hidden from
view by the substance into which they have forced their way, the
edible frog, kept in the indoor vivarium, when it quits the water,
generally settles down near its pool, leaving itself almost or quite
uncovered.

The edible frog is to be found almost all over Europe, and, as its
name implies, is valued by the epicure as well as the naturalist.
At one time frog-eating was apparently the privilege of the inhabi-
tants of France and Belgium only, but, through the influence of these
enthusiastic gastronomists, the fashion has extended itself across the
seas, so that stewed and fried frogs are now served in some Ameri-
can hotels, and preserved frogs’ legs—Iricassée de grenowilles—
are to be obtained in West-end provision stores of London.

It must not be supposed, however, that Rana esculenta is the
only amphibian so favoured by the appreciation of omnivorous
man, for several other species of frogs, and even of toads, are eagerly
devoured by both civilised and barbarous races in many countries.
The Chinese evidently deem frogs a luxury, and being either more

AMPHIBIANS 383

economical, or else less educated in the science of gastronomy than
their French cousins, partake of portions which are rejected by the
latter. Both frogs and toads are eaten largely by races in South
America, the West Indies, and many of the islands of the Pacific.

Although it has been the intention to deal in this volume with
British life only, yet I cannot refrain from mentioning the beautiful
and interesting little Green Tree Frogs (Hyla), so common in the
south of Europe, and so often sold by dealers in London and other
large towns.

These graceful little creatures thrive well in the vivarium, and
live in perfect harmony with their British relatives. They feed on
flies and various other insects, catching them very cleverly by a leap
and a thrust of the tongue. A peculiar feature of the Green Frogs is
their power of walking over a smooth perpendicular surface, hold-
ing on by the suckers which exist on the swollen extremities of their
fingers and toes.

They fall in so well with civilised life that they seem to be quite
friendly with their owner, and readily adapt themselves to the
changed conditions. Thus, if allowed to quit their home, they may
be seen walking up the window panes or the wall, catching the flies
that come within their reach ; and if placed on a dining-room table
they freely follow the same pursuit.

During the winter time, a vivarium containing Tree Frogs
should be kept indoors, and they will then rest during severe weather,
either snugly packed in a top corner of the case, or hidden under
moss or some other covering.

Toaps

Toads resemble frogs in many points of structure, also in their
metamorphoses and some of their habits ; but the differences between
the two are such that there is not the slightest difficulty in distin-
guishing one from the other.

The colour of toads is usually dull compared with that of frogs,
and the skin is dry and covered with a number of little warty pro-
jections. Their bodies are broad and bulky, and the belly much
swollen. The limbs are shorter than those of frogs, especially the
hind pair, which are not adapted for jumping ; in fact the creatures
seldom attempt to jump, and when they do, the length of one leap is
only three or four inches.

They are more terrestrial than frogs, repairing to the water only

384 LIFE IN PONDS AND STREAMS

for a short period in the breeding season, and their toes are only
partially webbed.

They breathe in the same manner as frogs, the floor of the mouth
being alternately raised and depressed to pump the air, which is
admitted through the valvular nostrils, into the lungs.

We have only two kinds of toads in Britain, yet we can lay
claim to a rather large proportion of the Kuropean species of Bufo,
for there are only three species in the whole continent. In fact it
has been doubted whether our Bufo calamita, or Natterjack, is not
a variety of the ‘continental B. viridis ; and if such is the case, then
there are only two European species, and we have both.

THe Common Toap (Bufo vulgaris)
(Plate VII, fig. 3)

The colour of this species is a dull dark brown, or sometimes a
lighter ashy tint; and the general dinginess of its appearance, to-
gether with the rough and warty character of its skin, the broad
and bulky form of its neckless body, and its extremely awkward
gait, have all had something to do with the almost unanimous
verdict that the toad is one of the uglest creatures in creation.
But if it 7s ugly, it has certainly one redeeming feature in the pos-
session of a pair of most lovely eyes. Let those who aver that they
cannot bear to look at a toad endeavour to overcome their innate
prejudice for creeping things, and take one home with a determina-
tion to see if there really be any charm in it, and it is then highly
probable that its bright eyes, and its curious ways, rendered more
pleasing by the readiness with which the creature adapts itself to a
domesticated existence, will soon enable them to look without a
shudder, and even to handle the creature without experiencing the
cold shiver that formerly sped throughout the body on touching its
rough and chilly skin.

There are still many who consider it their duty to declare that
the toad is a poisonous and destructive ‘reptile,’ that it can spit
forth a highly venomous fluid, that it can even vomit fire from its
cold and humid body, and that there is death in a mere glance from
its beautiful eyes! But all these and numerous other absurd beliefs
are received and handed down by persons who are naturally careless
about the truth, and have as a consequence no desire to observe and
investigate for themselves.

There is, however, some shadow of a reason for the frequent

AMPHIBIANS 385

opinion that the toad is venomous, even though it has no sting and
no poisonous bite, for its rough skin secretes a powerful acrid fluid
which, from the irritation it produces, is a valuable defence against
many of itsenemies. I have seen a cat take a frog in its mouth,
and even devour it; but one short experience of the flavour of a
toad is quite enough for pussy, who sneaks away with movements
and gestures that tell of an outraged tongue.

Some naturalists have made a study of this powerful secretion,
and have declared that a small quantity injected into the blood of a
small mammal will cause death in a very short time ; but it must
not be inferred from this that any danger is likely to accrue to our-
selves as the result of handling toads. In this respect they are
perfectly harmless, for the secretion, be it ever so irritable, will not
find its way through our impermeable skins. In fact it seems to
have no power as a poison unless introduced direct into the blood
system, and many animals, including our own common snake, de-
vour toads with a relish. There is no doubt, too, that toads are
eaten by human beings, but I cannot say to what extent the amphi-
bians are deprived of their venom-producing skin before they are
devoured.

It is perhaps doubtful whether we,are to look upon the irritating
substance merely as an excretion thrown off by the skin of the toad
in the process of blood-purification, just as poisonous matter is ex-
pelled from our own systems through the agency of the skin, kidneys,
and other organs; or whether it is secreted as a means of defence :
but the latter theory is more probable, for observers declare that
the amount of the irritant exuded by the skin is much greater when
the toad is disturbed and apparently in danger—that the defensive
fluid is secreted fastest just when it is required for defensive pur-
poses.

Bufo vulgaris starts from its winter quarters early in the spring,
and repairs to the water in April. Here the eggs are deposited in
long chains, generally a few weeks later than those of the frog, and
as soon as this duty is over it quits the pond for the remainder of
the season.

The tadpoles are very similar to those of frogs, but are darker
in colour, and are often so numerous as to give the appearance of
a black mud entirely covering the bed of the pond in which they
exist.

Let us now observe some of the movements and funny ways of
our captive toads. We remove one of them from its corner where

ce

386 LIFE IN PONDS AND STREAMS

it is wont to settle down in quiet during the hours of daylight. If
it is an old friend it takes its new position almost as a matter of
course, as if it thoroughly understood that it is expected to remain
still during the coming inspection; and when the examination is
over, crawls away to the same quiet nook with a laboured and awk-
ward step. Being now no longer in fear of its familiar master it
never attempts to leap, though when first captured it did occasion-
ally jerk its clumsy body forward to the extent of the length of its
hind legs.

But if the toad selected for observation is a recent captive it
will at once make sundry protests against the unprovoked assault.
As soon as it is touched it puffs out its already bulky body by
inflating it with air in such a way as to remind us of the ‘frog in
the fable,’ who lost its life in endeavouring to reach the dimensions
of an ox; andif its master persists in the unlooked-for intrusion
the toad still further attempts to fill its tormentor with fear by
lifting its body on its straightened legs till its stature is more than
doubled, and till it looks something like a headed balloon supported
on four short posts. This same comical attitude is also almost
invariably assumed when a toad is approached by a snake; and
should the latter attempt to swallow the toad, the difficulty of its
task is greatly increased (especially if the toad be a large one)
by the volume of air which the body contains, and which is not to
be expelled by the pressure of the snake’s jaws. I have seen the
inflation of a toad’s body carried to such an extent that, when
held up to the light, it was a veritable air-ball, so transparent that
the backbone with its surrounding muscles could be easily traced,
and the internal organs could be seen occupying only a very small
proportion of the cavity, mostly near the head.

The feeding of toads is as interesting to the observer as that of
frogs. The creatures are all at rest, drowsy and lethargic. We
drop a worm an inch or two from one of them. Immediately the
toad is full of life. Its eyes brighten, its head is turned sharply
toward the anticipated meal. Every movement of the worm seems
to add to the vivacity of the toad. The latter takes a sharp step
towards its prey; it breathes quickly and twitches its toes with
excitement ; and then, with a sudden thrust of the tongue, it seizes
the poor worm, which, after a few gulps, assisted by a few awkward
movements of the toad’s forelegs, rapidly disappears from view.

Flies, beetles, grubs, and other small creatures are captured by
the tongue after the manner of the frogs, this organ being similarly

ShABSE . terene VS ee Oe EEE Eee ee eee

OE oe tO

AMPHIBIANS 387

adapted for the purpose, but differing from the tongue of the frog
in that it is only very slightly notched at the tip.

Both frogs and toads frequently make the mistake of attacking
a worm that is too large to be accommodated with ease in the
offender’s stomach. After very great efforts on the part of the
batrachian the poor victim nearly, or perhaps entirely, disappears.
But the aggressor is ill at ease; and, having found out its mistake,
it suddenly and forcibly ejects its exhausted prey with a gesture
that suggests pain and disappointment. However, the affair does
not always end here. The batrachian often has another try, which
is sometimes more satisfactory, but it may end in the same in-
glorious way as the first attempt.

The toad, like its relatives of its own and the Rana genera, very
seldom attacks a creature that is not moving. Often, when it is
just ready for the fatal thrust, the anticipated prey ceases to move.
It then watches closely for a short period, and if no further signs of
life are exhibited it will leave in search of more animated scenes.
But the toad is easily deceived in the matter of motion. Just as a
child in a moving train fancies that the outside landscape has taken
to flight, so to a toad that is moved all motionless objects seem to
be active. Hold a dead worm before a tame toad, and it refuses to
snap at the dainty. But suspend the worm by a thread, and,
taking your pet on your hand, move it up and down or from side to
side near the morsel. Things now look different to the toad, and
probably the meal is as much enjoyed as if the worm were actually
alive.

I may mention one other fact concerning the toad, which
also, by the way, characterises its fellow-batrachians, viz. the
periodic casting of the skin. If you keep toads in confinement
you will occasionally observe one making its appearance in a some-
what altered ‘garb. Its coat is lighter in colour, and the markings
are more distinct. You come to the conclusion that it must have
cast its old coat, and you make a search for the old garment, but in
vain. But this is an event of rather frequent occurrence—probably
four or five times at least for each toad during one season—so that
probably before long an opportunity will present itself for the
solution of the mystery.

When a toad is about to cast its skin it nearly always retires to a
quiet nook. At first the skin splits down the back and along the top
of the head. The latter is soon released, and the creature, seemingly
very uncomfortable with its ragged coat hanging over the sensitive

cc2

388 LIFE IN PONDS AND STREAMS

skin, continues to struggle to get free from its useless encumbrance.
Both fore and hind limbs are used to rub off the loosened coat ;
and, often before the whole is free, the toad commences the
economical operation of swallowing the whole of its cast-off
wardrobe.

Apparently the toad can dispose of its skin at will, or else the
process is accelerated by a change of condition, for the removal of
the creature from one kind of home to another—from the garden
to an indoor vivarium, for example-—will almost invariably lead to

a change of garment.

Ture Narrersack Toad (Bufo calamita)

Although the Natterjack is very similar in general build and
appearance to the common toad, it is easily distinguished by its
yellowish or olive-brown colour and the pale yellowish line that
runs down the middle of the back. The warts on its surface are
also more prominent, and exhibit a decidedly reddish tinge; but
the dark marblings of the skin, which are generally rather con-
spicuous in the common species, are less distinct in Calamita.

It is further characterised by its nimbleness, being far more
active and less awkward in its movements than its vulgar cousin.
Yet it never attempts to jump, not even when pursued, but crawls
away quickly or even runs. Natterjacks are rather gregarious in
their habits, one being seldom seen alone. I once met with quite
a colony of them in a patch of wooded upland in Hampshire.
The first one that attracted my attention ran quite briskly under
some dead leaves that filled a deep rut in the roadway. In the
twilight I mistook the creature for a small mammal, but a search
among the leaves soon revealed two natterjacks—a ‘find’ that was
immediately followed by the capture of several others.

At one time this species was moderately common in several
localities round London, but it now seems to have almost quitted
the neighbourhood of the metropolis. In the fens and various
other marshy districts it is still common; and during the summer
it wanders far from the water, often journeying over high and dry
moors, where it is protected from the blazing sun only by small
furze clumps, heather, and scanty grasses.

The activity of the natterjack as compared with the common
toad is shown not alone by its running, for it is equally expert as a
digger. ° When about to rest it scoops out a comfortable hollow in
the ground, where it lies in perfect safety, and sometimes burrows

LMIA ALV TL

AMPHIBIANS 389

to the depth of several inches. It is also a good climber, but, like
the common toad, succeeds best in this mancuvre when working
its way up a crevice through which it can force its body by means
of its knees. In this way both Vulgaris and Calamita will some-
times ascend old walls and hollow trees.

The eggs of Calamita are laid in strings of great length, and
are generally deposited in May or the beginning of June; and the
metamorphoses are not completed till the end of the summer or
the autumn.

NEwtTs or Erts

The three species of British newts or efts have so many cha-
racteristics in common that it will be well to deal with their general
features before mentioning their individual peculiarities, and thus
avoid an unnecessary repetition.

Compared with the preceding Batrachians their bodies are long
and slender, and their legs short and equal ; and the tail, which in
frogs and toads disappears in the process of development, remains
permanent in the newts.

The general form of a newt is very similar to that of a lizard,
and this resemblance has led to the common application of the name
‘ water lizards’ to the former. But, to avoid confusion, it may be
well to note the more obvious distinctions between newts and lizards.
Newts are amphibious animals, and even truly aquatic at certain
periods of their existence ; while lizards inhabit dry heaths, moors,
and banks. Newts have a soft moist skin, resembling that of frogs ;
but lizards are covered with a dry scaly skin, much like that of a
snake. Newts have flattened tails adapted for swimming, while the
tails of lizards are round and tapering. Also, newts in their earlier
days, pass through a series of stages similar to those of the frog ; but
young lizards, on their first appearance in life, are formed just like
their parents. And, further, the close relationship existing between
the newts and our other amphibians is clearly exhibited by the shape
of the head and the wide gape; by their prominent eyeballs, which
are retractile, and readily observed on the roof of the mouth, and
by the arrangement of the eyelids; also by their method of breathing,
which corresponds exactly with that force-pump action described
when treating of frogs.

During a large part of their existence newts are very inactive,
for they hide under the cover of walls, stones, &c. during the sum-
mer days, and creep about leisurely in search of food at night ; and

390 LIFE IN PONDS AND STREAMS

throughout the periods of severe weather they remain motionless
in theirretreats. This will account for the generic name—‘ Molge’—
a name derived from the Greek and meaning ‘ slow.’

Newts are most active during early summer—from April to the
end of June—at which season they are to be seen in almost every
pond, and this is the best time to procure them for study and for
the ornamentation of our aquaria.

They are easily caught. The only implements required are a
small gauze hand-net and a large metal box, such as an ordinary
bait-can, in which to convey the specimens home.

As you walk round a weedy pond you will observe here and there a
newt gracefully swimming with an undulatory movement of its tail
toward the centre. Its fear of the monster on the bank is evidently not
very great, for its flight is not at all hurried, neither does it trouble
to swim any great distance from you; and a quick sweep of the net
among the weeds will generally secure the prize, and often one or
two others that happened to be among the foliage in the path of the
net. Sometimes, in fact often, the newts in a pond are so numerous
that they may be secured, five or six at a stroke, without attempting
to look for them, but by simply sweeping the net haphazard among
the weeds.

The schoolboy’s method of catching newts is usually not so pro-
ductive, though it may be more exciting. An extempore fishing-rod
is made of a cut stick and a piece of string. An earthworm is tied
to the lower end of the string and let down into the water, either
just in front of a newt that is seen or in a spot where some of the
creatures are supposed to be hidden. A gentle tugging is presently
felt, and is sometimes rendered visible by the bobbing of a piece of
cork used as a temporary float. Now is the time for the exercise
of a little patience, and judgment. Give the hungry amphibian
sufficient time to swallow the worm, or, if the latter be a large one,
time to get a portion well lodged in its stomach; and then a sharp
haul lands the creature on the bank before it has had time to free
itself from the treacherous luxury.

During early summer the female newts are busily engaged in the
deposition of their eggs. These are not laid in masses like those
of frogs, nor in the long strings after the manner of toads, but de-
posited singly on the leaves of aquatic plants. It is interesting to
watch this procedure in the aquarium. While the egg is being de-
posited, the hind legs of the newt are brought against the opposite
edges of the leaf that is to support it, and in this way the leaf is

AMPHIBIANS 391

curled in such a manner as to partially enclose the egg. The value
of this precaution is evident to those who have seen the lively little
stickleback and other small fishes snapping away at the ova almost
immediately after they have been laid; but I am very doubtful
whether this instinctive action on the part of the female newt is as
protective as is generally supposed. Very frequently the leaf which
is curled as the egg is being deposited is sufficiently elastic to regain
its original form as soon as the pressure is removed, and those leaves
which remain curled generally leave the egg more or less exposed.
Moreover, I have often observed the newt lay its eggs on the flat
surface of a large leaf which it made no attempt to curl, or which
was so large and rigid that any endeavour onthe part of the creature
to conceal the egg would be useless, and this when the aquarium
contained other aquatic plants which might have served its purpose
admirably.

Again, how does the newt manage when in a pond which con-
tains no aquatic plants at all?—and we often find them in such.
This may be answered by doing a little dredging in the pond during
the breeding season, when the eggs will be found attached by their
gelatinous covering to pieces of stick, dead leaves, and various other
substances, and generally laid without any apparent attempt to con-
ceal them.

The segmentation of the ovum is very similar to that of frogs
and toads; in fact the whole early history of newts is much like
that which we have somewhat fully detailed in the case of the com-
mon frog; but there are a few interesting peculiarities which may
be noted. The external gills of the tadpole of the newt are longer
and more plumelike ; its suckers also are longer. Its forelimbs
appear first, and not the hind pair as in frogs; and, as has been
already noticed, the long tail is permanent.

The tadpoles are easily caught with a net, but if it is desired to
keep them alive they must have plenty of room and be well supplied
with weeds; otherwise they will almost surely become addicted
to cannibalism till only a few survivors remain.

Then, again, it must be remembered that young newts leave
the water soon after they have assumed the adult form, and that
they do not generally return to it again till they reach maturity
three or four years after. Soif you are desirous of rearing them
throughout their early years, they must be allowed to leave the
aquarium as soon as they begin to make attempts to climb out
of the water, and must then be placed in a little outdoor nursery

392 LIFE IN PONDS AND STREAMS

~

in a shady and damp corner where they have the shelter of a
rockery, and where they are likely to find abundance of worms and
insects for food. On reaching the period of adult life they wander
about in the spring time in search of water in which to prepare
for their progeny.

Nothing will suit them so well at this period as a small pond
well supplied with aquatic plants; but as it is
impossible to watch their movements with ease
in such a home, a few may be transferred to a
glass-fronted aquarium for observation.

The adult newts generally remain in water
throughout the spring and early summer, and
if kept in captivity during this season they
must be fed occasionally with worms—the com-
mon earthworms of the garden ; this will furnish
Frc. 309._-Younag 2®2 opportunity of witnessing another phase of

Newr (Molge newt nature.
os ulgaris), We throw a small worm into the aquarium.
ian: Um aie Presently a newt is attracted by its movements,
APPEARANCE or 2nd swims gently toward it till within a quarter
THE EXTERNAL of an inch or so, and then snaps at it suddenly.
eee In another minute or two the struggling worm
has entirely disappeared.

3ut if the worm happens to be a larger one, say about three or
four inches long, the matter is not quite so simple, and may end in
disappointment to the newt as well as death to the poor worm.
Newts do not know the most effectual way of seizing a worm, and
frequently make the mistake of snapping at the middle and com-
mencing to swallow it at that point. In this case the newt has to
labour against the double thickness which has to pass through its
mouth and gullet. This often proves too much; and after many
severe struggles to dispose of its prey, it is obliged to relieve itself

by disgorging it entirely.

If, however, it is more fortunate in seizing the worm at one end,
there is generally a trouble of another kind awaiting it, for one of
its fellows, attracted by the furious struggles of the poor worm,
makes a dash at the other end! Then follows an exciting scene.
Both newts continue to swallow the worm, till at last their jaws
meet, cach one having disposed of about one half. But still they go
on, each one taking gulp after gulp, with a vantage sometimes on
one side and sometimes on the other. After a time, however, the

AMPHIBIANS 393

weaker newt shows signs of exhaustion, and, relaxing its hold on
the worm, allows each gulp of its fellow to deprive it of a portion of
the meal that had already been swallowed ; and then, finding no hope
for the retention of the meal, suddenly ejects the remainder and
swims away. But the fortune of the sole possessor of the worm is
no brighter, for its stomach is distended to its greatest capacity
at the time that the whole was left to its share; and after many
unsuccessful attempts to dispose of the free end, it is obliged to
eject even that which had been so satisfactorily disposed of.

There is yet another feature of interest common in our newts,
viz. the periodical moultings or castings of the outer skin. You
may sometimes observe in your aquarium a newt with a little
loose skin, very thin and transparent, hanging from its head or
neck. Watch this one carefully, and you will notice peculiar move-
ments of its body and limbs not observable in the others. Its fore-
limbs are occasionally brushed over the front part of its body as if
to remove the cause of some troublesome irritation. It also swims
between the weeds, rubbing its body along the stems and leaves,
_and sometimes turning itself on one side to better perform its task.
“All this time the skin is seen to be gradually peeling off, till it hangs
beside the tail as the creature moves through the water. The
movements above described are continued, assisted now by a rubbing
of the hind limbs; and before long the delicate skin, with two
pairs of exceedingly fragile but perfect gloves, may be seen floating
freely in the water. Often this old coat is immediately devoured by
the creature that cast it. Sometimes another will make a meal of
it. But frequently it remains floating for a long time among the
weeds, or settles at the bottom.

Take the skin out of the water and it immediately becomes a
shapeless and almost invisible film, hardly to be moved without
injury. Although so delicate it can be easily preserved as a per-
manent specimen for a museum of animal curios and treasures.
For this purpose it should be placed in a small bottle or specimen
tube with sufficient water to enable it to float freely. Then a few
drops of spirit—not more than one-fourth the volume of the water
—should be added.

Having now dealt with a few of those characteristics which are
common to the three British newts, we will proceed to note those
peculiarities by which we are enabled to distinguish between them.

id)
an)
n=

LIFE IN PONDS AND STREAMS

THe GREAT Warty Newt (Molge cristata)

(Plate VIII, figs. 1 and 2)

This is the largest of our newts, and measures from five to six
inches in length when fully grown. It may be known at once by
the rough warty skin which gives it its popular name. Its colour
is very dark—almost black—above, but the under side is a beautiful
bright orange colour, relieved by bold and irregular black markings.
Along the sides are numerous white spots, and a loose fold of the
skin forms a kind of collar round the neck.

There is not much difference between the sexes till they reach
maturity—that is, when they repair to the water for breeding pur-
poses in the spring of their fourth year. At this period the skin
becomes much rougher, the little warts, hardly visible before, now
becoming very prominent. The colours also grow brighter, and a
conspicuous, deeply notched crest gradually develops on the back
and tail of the male, and the light-coloured stripe on each side of
the tail becomes a beautiful silvery blue.

The deposition of the eggs begins in April, and continues to the *
end of June or even into July; and the autumn is well advanced
before the latest tadpoles have undergone their metamorphoses.

Each egg consists of a thin and transparent membranous cap-
sule, containing a white yolk suspended in a colourless fluid, and
surrounded by a gelatinous envelope which glues it in its place.

In three or four weeks the young tadpole is free, and in about
another month it is provided with its fore pair of limbs; but it is
usually quite five months after the hatching of the egg before the
hind limbs, the lungs, and the other permanent organs of the adult
form have so far developed that the young newt is in a position to
ramble at large on terra firma.

The growth of the newt is now slow compared with that of its
earlier career, the increase in its length being at the rate of about
an inch each year; and when fully grown, at the end of its fourth
summer, it measures from five to six inches.

It has often been asserted that newts never return to the water
from the time of infancy till the age of maturity, but Cristata is
certainly an exception to this rule. I cannot say that every one of
the species returns to the ponds each summer; in fact it would
appear to be otherwise, for nearly all that are taken with the net
are either very young ones just undergoing their transformations,

AMPHIBIANS 395

or are those of mature years; but I have taken specimens of all
ages—one, two, three, four, or more years—from the same pond at
the same time.

Towards the end of the breeding season the crest of the male
begins to grow smaller, and his colours to fade ; and as the autumn
sets in, both males and females wander out of the pond, often to
some considerable distance, and seek out a snug hole in which to
spend the winter, several often huddling together in the same little
nook.

Cristata, is a common species, and widely distributed. It is
particularly abundant in the ponds round London, even in close

Fie. 310.—Mane anp Femaue Cristata, REDUCED IN SIZE

proximity to suburban dwellings and in the ponds and ditches of
the outlying commons. But, in the former case by the untiring
industry of the builder, and in the latter by the efforts of the
authorities to remove all traces of wild Nature from our recreation
grounds, our cockney batrachians are being rapidly annihilated or
else driven away from the outskirts of town.

396 LIFE IN PONDS AND STREAMS

THE Common oR SmMootH Newt (Molge vulgaris)
(Plate VIII, figs. 3 and 4)

This is by far the commonest of our newts, for it is to be found
in ponds and ditches almost everywhere; and, at times when it
prefers to live on land, may be seen snugly housed in the daytime
under loose bricks and stones quite within the precincts of our
towns, or under the shelter of garden walls, and even in damp
cellars and outhouses.

It is about four inches long when full grown, and its skin is
smooth and very variable in colour. The back and sides are either
yellowish, grey, brownish or olive, and spotted with a darker colour.
The spots are larger and more numerous in the male than in the
female, and the general appearance is always much brighter during
the breeding season than at any other time. On the head are five
dark streaks, more conspicuous in the male sex. One of these runs
longitudinally along the middle of the head, but does not extend
quite to the front. Two others, one on each side of this, almost
meet in front, forming a large V ; and the remaining two lines are
broken by the eyes.

The under side is yellowish generally, but of a bright orange in
the spring, and is boldly spotted with very dark brown or black.

In the breeding season the male is provided with a notched
crest along the back, extending to the tip of the tail; and the tail is
also deeply fringed below. The female, too, is crested, but the
crest is very narrow and is not notched. .

As with Cristata, the crest gradually disappears as the summer
advances and the breeding season terminates; but it would seem
that this season may be prolonged into very late autumn if delayed
by a very severe spring, or commence very early in the year when
the spring is exceptionally mild, for I have repeatedly taken both
the undeveloped young newts and also the adults with full crests in
the months of December and January when the weather has been
mild.

It will be noticed that the feet of Vulgaris are not fully webbed
and adapted for swimming, but that the toes are only slightly
fringed. Even this is hardly observable in the female, and in the
male the fringe disappears with the crest towards the autumn.
The tail is the chief organ of locomotion, and the legs are used to
assist the progress of the creature only when it is moving on land,

AMPHIBIANS 397

on the bottom of a pond, or among very dense weeds. When it is
swimming, therefore, the legs are a barrier to its progress by offer-
ing resistance to the water. But this resistance is reduced to a
minimum by the creature’s habit of bending them backward while
itis swimming. At this time the movements of Vulgaris, and
especially of the male, are rendered exceedingly graceful by the
undulatory movements of the broad and prettily coloured tail and
the easy position of the apparently loosely jointed limbs.

According to some observers the eggs of the common newt are

Fic. 311.—Tue Common Newr (Molge vulgaris), Mate AND
FEMALE, NATURAL SIZE

sometimes laid in chains; but, I believe, these chains are never
free and floating in the water like those of toads. The eggs are
generally deposited singly, but it is not at all uncommon to see a
line of half a dozen or more lying close together on a single leaf
or a stem. Whether the latter were really connected by their
gelatinous envelopes at the time of laying, or whether they simply
lie in contact, I cannot say; but where such rows of eggs exist a
number of isolated ova are almost invariably found; and if we
watch the female Vulgaris while engaged in the act of laying, we

398 LIFE IN PONDS AND STREAMS

shall observe that the eggs are often deposited singly at consider-
able intervals of time, and that she often travels from leaf to leaf
and from plant to plant during these intervals.

If kept in captivity Vulgaris exhibits a marked aversion to
the water towards the end of the summer, and manages to get out
of an ordinary glass aquarium with ease if there is no cover to
prevent its escape. Of course the glass is much too smooth to
admit of ordinary climbing, but the newt’s toes, especially after
having been above water for a short time, become partially dry and
stick to the glass, and so allow it to pull itself a little way up.
Then the skin of the belly, and, a little later, that of the hind toes,
also assist in supporting the body, so that the creature can steadily
creep up the glass.

It is perhaps hardly necessary to add that, in spite of all the
ill things that have been said of newts, all the three species are
perfectly harmless. It has been said that they sting, that their
bite is poisonous, that contact with their skin is dangerous, that
horses which drink out of a pond in which they exist will certainly
die. But there is not the slightest foundation for these and the
various other superstitious beliefs that have been and are still held
by the thousands who are willing to condemn the creature without

a trial.
THe PatmMatE Newt (Molge palmata)

This species is not nearly so abundant as the two preceding, and
is decidedly local. It was first recognised on the Continent a little
more than a hundred years ago, and first recorded in Britain about
fifty years since.

Specimens have been taken in Devon, Herefordshire, Somerset,
and various other counties of England; also in Scotland, more
particularly in the south.

Palmata is considerably smaller than Vulgaris, and may be
further distinguished by the following characters :

The colour is an olive-brown above, marked with darker spots
which are much smaller than those of Vulgaris; and underneath
it is a bright yellow or orange. The female is much paler than the
male, but the darker markings are similarly arranged. During the
breeding season the male is crested, but the crest is very dark, and
much narrower than that of the last species; its edge is also quite
free from notches. The female, too, is slightly crested, and has a
yellow fringe on the lower edge of the tail.

|

AMPHIBIANS 399

The tail of the male is very blunt at the extremity, looking
almost as if it had been cut, but it terminates in a slender filament.
That of the female is more pointed, and the filament is almost
entirely absent, being represented by only the tiniest projection.

Another peculiarity of the species is a projecting fold of the skin
forming a longitudinal ridge or keel on each side of the body, and
giving it, together with the crest on the back, a somewhat triangular
appearance.

Further, the feet of the male are generally of a very dark colour,
and the toes are fully webbed during breeding time; but, as with
Vulgaris, the web gradually disappears with the crest, late in the
summer, the toes becoming free and cylindrical in form.

It will be observed from the above remarks that the chief of the
distinguishing characteristics of the present species belong to the
male only; and on this account there may be some difficulty in
the identification of the females, which closely resemble the same
sex of the last species in general appearance. But this difficulty
vanishes when the two are examined side by side.

Acanthopterygii, 352
Acentropus niveus, 322
Acephala, 127

Acerina cernua, 356
Acilius sulcatus, 332
Actinophrys sol, 106
Actinopterygii, 356
Aischna borealis, 272

— cyanea, 262, 270

— grandis, 270

— juncea, 271

— mixta, 272

— rufescens, 270
Aischnide, 252, 259, 270
AE schnina, 258

Agabus biguttatus, 332
Agrion mercuriale, 275
— puella, 274

— pulchellum, 274
Agrionide, 252, 259, 273
Agrionina, 258, 259
Alcohol, 49°

Alder flies, 285

— — setting, 58
American pondweed, 87
Ameba, 3, 100
Amphibians, 14, 360

— metamorphoses, 361
Anacanthini, 352
Anacharis, 87

Anazx formosus, 272
Ancylus, 168, 169, 176, 292
— fluviatilis, 176

— lacustris, 176
Anemones, 5
Anodonta, 127,
— anatina, 160
— cygnea, 160
— food, 136
— nervous system, 135
— shell, 129

Ants, 18

Aphides, 11

Aquaria, 71

158, 160

INDEX

Aquarium, cement for, 75
— construction, 74
— fountain, 80

| — net for, 27

Aquatic beetles, 322
— coleoptera, 322
— diptera, 298

— hymenoptera, 343
— insects, 202
lepidoptera, 316
moths, 316
neuroptera, 244

- plants, 86
spiders, 195

- springtails, 240

_ Arachnide, 196

Arachnoidea, 9, 180
Argyroneta aquatica, 198
Arrowhead, 93
Arthropoda, 2, 8, 179, 196
Asellide, 193

Asellus aquaticus, 193
Astacus fluviatilis, 180
Aurocorisa, 214

Aves, 14

Arolotl, 363

BaRBEL, 353

Beautiful China Mark, 321
Bees, 13

Beetles, 13, $22

— setting, 60

Bell animalcules, 103
Birds, 14

Bithynia, 164, 292
Bivalve molluses, 7,
Bleak, 353
Bloodworm, 307
Boatman, 11, 223
Boxes, collecting, 19
Brachionus urceolaris, 120
Brachytron pratense, 272
Branchiopoda, 194

26, 127, 147

402

Bream, 353

Broad-leaved Pondweed, $0
Brown China Mark, 321
Bryozoa, 124

Bufo calamita, 388

— vulgaris, 384

Bugs, 11, 214

Bullhead, 353, 358
Butterflies, 13

CaApDDIS cases, 289, 294

— flies, 12, 28, 287

— worms, 295

Callitriche verna, 91
Calopterygide@, 259, 272
Calopteryx splendens, 273
— virgo, 273

Carnivorous Water Beetle, 325
Carp, 353, 354

Cataclysta lemnata, 319
Centipedes, 9
Cephalophora, 138
Ceratophyllum demerswm, 88
Chameleon fly, 311

Charr, 353

Chelifers, 9

China Mark Moths, 24, 319
Chironomus, 306
Chloroperla virides, 283
Chrysalis, 11

Chub, 353

Close-leaved Pondweed, 91
Cockroach, 12
Celenterata, 2, 4, 109
Coleoptera, 13, 322

— setting, 60

Collecting, 15

Collection, care of, 66
Collector’s work, 1
Columella, 140

Common Newt, 396

— Toad, 384

Corals, 5

Cordulegaster annulatus, 249, 259
Cordulegastrida@, 259, 269
Cordulia enea, 261, 268
Corduliida, 259, 261, 268
Corethra, 309

Corixza, 230

Corixide, 230

Cottus gobio, 358

Crabs, 9

Crayfish, 9, 180

— preserving, 63

Crickets, 12

Cristatella 126

INDEX

Crown animalcule, 119
Crustacea, 9, 62, 179, 180
— preserving, 62

Culex, 299

Curled Pondweed, 91
Cyanide bottle, 54
Jyclops, 9, 62, 194
Cyprinus awratus, 354
— carpio, 354

Dace, 353

Daphnia, 193

Decapoda, 192
Demoiselles, 272
Deronectes, 332
Dinocharis pocillum, 120
Dipping bottle, 30 ;
— tube, 28, 40

Diptera, 13, 298
Dolomedes, 200

Dragon flies, 12, 28, 244

— — classification, 258

— — setting, 58

— — table of families, 262
Dredge, 17

Dredging hook, 19
Dreissena polymorpha, 160
Dreissenide, 147, 160
Drone fly, 313

Duckweeds, 86

| Dyticus marginalis, 325

| —— larva, 830

Dytiscide, 322

Echinodermata, 2, 6
Edible frog, 381
Edriophthalma, 192
Eel, 353 :

Efts, 389

Elis eneus, 348
Enallagma cyathigerum, 275
Epeiride, 198
Ephemeride, 275

— setting, 58
Hristalis tenax, 313
Huglena, 105
Huplexoptera, 12

FIsHEs, 14, 346
Flagellata, 105
Flags, 93

Fleas, 13
Floscularia, 119
Flowering rush, 93

_ Flukes, 6

Freshwater bivalves, 147
— crustaceans, 179
— limpets, 292

— molluscs, 127

— mussel, 127

— polype, 109

— shells, 63

— shrimp, 27, 62, 192
— univalves, 161
Frog, 364

— eggs, 365

— skeleton, 373

— tadpole of, 368

— tongue, 379

Gammarus, 192
Garden pond, 85
Gasteropoda, 138, 161
Gastrosteus aculeatus, 357
Gerrida, 220

Gerris, 220
Gill-footed crustaceans, 194
Gnat, 299

— eggs, 303

— larva, 303

— pupa, 305

Gobio fluviatilis, 356
Gold fish, 354
Gomphide, 259, 269
Grasshopper, 12
Grayling, 353

Great Caddis Fly, 298
— Warty Newt, 394
Green Drake, 280
Grey Drake, 280
Gudgeon, 353, 356
Gymnophiona, 363
Gyrinida@, 24, 322, 334
Gyrinus bicolor, 336
— natator, 334

— — larva, 336

Harry Whirligig, 536
Halesus auricollis, 291
Head-bearing molluses, 138
Helicide, 177

Helia aspersa, 139, 177
Hemiptera, 11, 213
Heteroptera, 214
Hirudimea, 121

Hirudo medicinalis, 128
Homoptera, 214

Horned floseule, 119
Hornwort, 88

INDEX

Horse Leech, 123
Hydra, 6, 109
Hydrachna, 200
Hydrobia, 165

Hydrocampa nympheata, 321

— stagnata, 322
Hydrocampide, 24, 319

_ Hydrocorisa, 214, 223

Hydrodromica, 24, 215
Hydrometra, 215
Hydrophilide, 322
Hydrophilus piceus, 337
— — larva, 341

— — pupa, 342
Hydroporus, 332
Hymenoptera, 13, 205, 343

Infusoria, 4, 102

Insects, 9, 180, 202

— metamorphoses, 11, 203
— preservation, 53

| — setting, 56

— structure, 203
Invertebrata, 2
Ischnura elegans, 275
Isopods, 192

Itch insect, 9

JELLY fishes, 2, 5

403

Lamellibranchiata, 127, 147, 151

Lamprey, 350
Larva, 11
Laurel box, 55
Leeches, 7, 121
Lemna, 86
Lepidoptera, 13, 316, 317
— setting, 58
Lestes nympha, 274
— sponsa, 262, 274
Leuciscus phoxinus, 355
— rutilus, 355
Leucorrhina, 267

~ pectoralis, 263
Libellula, 267

- quadrimaculata, 265

Libellulida@, 252, 254, 259, 262

- classification, 267
Libellulina, 258
Libellulina, 258
Lice, 11
Limnea, 168, 175, 292

auricularia, 96
— involuta, 175

404

Limnea palustris, 174
peregra, 96, 174, 175
— stagnalis, 96, 174, 175
— truncatula, 174
Limneide, 167, 169
Limnophilus, 291
Lingual ribbon, 141
Live-box, 40
Loach, 353, 356
Lobsters, 9
Lophopus, 125
Lycoside, 200

Mammats, 14

May flies, 12, 275

— — setting, 58

Medicinal Leech, 123

Melicerta, 120

Microscope, compound, 36

— lamp for, 44

— management of, 44
- simple, 36

— cells, 40

Microscopes, 35

Microscopic life, preservation of, 49

Migration of molluscs, 149
Millepedes, 9
Miller’s Thumb, 358
Minnow, 353, 355
Mites, 9
Molge cristata, 394
— palmata, 398
— vulgaris, 396
Mollusca, 2, 7, 95, 127
— migration of, 149

~ semi-aquatic, 177

— univalve, 161, 167
Moss polypes, 7, 124
Moths, 13, 319
Mud Eels, 363
Museum, pond-hunter’s, 48
Myriapoda, 9, 180

NATTERJACK toad, 388
Naucoris cimicoides, 239
Nemachilus barbatulus, 356
Nematoidea, 115
Nematoids, 115

Nemoura variegata, 283
Nepa cinerea, 233
Neritide, 162, 163
Neritina, 26, 163

— fluviatilis, 163

Nets, 16

Net for aquarium, 27

INDEX

Newroptera, 12, 244
Newts, 389
Notonecta glauca, 22
Notonectide, 223
Nuphar lutea, 93
Nymphea alba, 98

Octonoculina, 197
Odonata, 244

— classification, 258

— setting, 58
Odontophore, 141
Operculum, 162
Orectochilus villosus, 336
Orthetrum, 267
Orthoptera, 11, 322

- Patmate newt, 398
_ Paludina, 164

— vivipara, 96
Paludinide, 162, 164
Paramecium, 102
Paraponysx stratiotata, 320
Parnide, 342
Pectinibranchs, 162, 166
Pelobius Hermanm, 333
Perca fluviatilis, 356
Perch, 356
Perfoliate Pondweed, 91
Peristome, 140

Perla, 281

Perlide, 281

— setting, 58
Petromyzum fluviatilis, 350
Phryganea grandis, 298
Phryganeide, 291
Physa, 168, 173
Physostomt, 352

Pike, 353

Pisces, 14

Pisidium, 97, 151, 152, 153, 155, 291

Pitcher rotifer, 120

Planorbis, 96, 168, 169, 172, 292

— corneus, 96, 170, 178
Plantains, 93

Plant lice, 11
Platetrwm, 267

— depressum, 249, 259, 262, 2
Plumatella, 124

Podura, 240

Polystomata, 2, 4, 107
Pond-hunter’s museum, 49
Pond skaters, 220

Pond sponge, 107, 109
Pope, 356

INDEX 405

Porifera, 2, 4, 107 | Sea urchins, 6
Potamogeton, 89 Semi-aquatic molluses, 177
— crispus, 91 Senoculina, 197

— densus, 91 Sericostoma multiguttatum, 291
--- natans, 90 Sessile-eyed crustaceans, 192
— perfoliatus, 91 Setting boards, 56
Preserving crayfishes, 63 — insects, 56

— crustaceans, 62 Shells, preserving, 65, 65

— insects, 53 } Shrimps, 9

— natural history objects, 48 — freshwater, 62

— in alcohol, 49 Sialida, 285

Proteus, 363 — setting, 58

Protozoa, 2, 3, 100 _ Silver beetle, 337
Pseudopodia, 3 Similis, 165

Pteropoda, 138 Siren, 363

Pulmonifera, 167 Skeleton rotifer, 120
Pulmonobranchiata, 162,167 Slipper animalcule, 102
Pupa, 11 Slugs, 8

Putris, 177 Small China Mark, 319
Pyrrhosoma minium, 275 Smooth newt, 396

Snails, 8, 138

Snake flies, 12

. ad . o »
Radiolaria, 3 mea aay 352
Rana esculenta, 381 ms Jars, 94

— temporaria, 364 — tubes, 68 as

wee L 365 -* Spheriide, 26, 147, 148, 151, 154
et <i 373 Spherium, 151, 154, 291

= q e je of ea Spiders, 9, 195

Te sana = apa _ Spine-finned fishes, 352

— tongue, 379 | Sponges, 2

Ranatra linearis, 237 ra ida 107

Ranunculus aquatilis, 89 ) Firs 107

Rat-tailed maggot, 313 Spot eae "39

Relaxing insects, 59 dt rts

Reptile % 14 Springtails, 11

L Squirts, 7
Rhizopods,!3 Starfishes, 6
Rhynchota, 11, 213 Starwort, 91
River crayfish, 180 , 10

Stentor, 107

Hearne ys Soe Stephanoceros, 119

— sponge, 107, 108 icklebac
Roach, 353, 855 / Stickleback, 357

j Stone flies, 12, 28, 28
Rotatoria, 116 Stone flies, 12, 28, 281

Rotifers, 7, 116 — — setting, 58

“= : | Store boxes, 69
Rotifer vulgaris, 118 “hea an
Rudd, 353 Strainer, 33

/
exe | Stratiomys, 311
rae sag | cha ie, $11
neiey, 6 - furcata, 313
Succinea, 177
— putris, 23
Sugar lice, 11
Sun animalcules, 106

SALMON, 353
Scaphopoda, 138

Scoop, 17 | Sweet flag, 93

Scorpion flies, 12 — Sympetrum, 265, 267
Seraper, 17 — Fonscolombii, 263

Sea cucumbers, 6 — meridionale, 263

— firs, 5 — scoticum, 266 7

— mouse, 7 _ — vulgatum, 265

406 INDEX

TAPEWORMS, 6 | Valvatide, 162, 166
Teeth of bivalves, 131 | Vermes, 2, 6, 114
Teleostii, 352 Vertebral column, 2
Tench, 353 | Vertebrata, 2, 14
Tetradecapoda, 192 Vorticella, 103

Threadworms, 6, 115
Three-spined stickleback, 357

Thyme, 93 | Wasps, 18 :
Thysanura, 11, 240 | Water boatmen, 223

Ticks, 9 — bugs, 215, 223 .
Tipulide, 306 | — crowfoot, 89

Toads, 383 | — fleas, 9, 62, 194

Tracheex, 9 — gnats, 11, 24, 215

Trichoptera, 12, 287 — hog louse, 193 ©

Trout, 353 | — lilies, 98

Tube-bladdered fishes, 352 — measurers, 215

Turbellarians, 6, 115 | — mites, 200

Turpentine as a preservative, 51 | — plantains, 93

| — scorpions, 11, 2338
: | — spiders, 195
Umpsruicus, 140 | — springtails, 240
Unio, 159 — thyme, 93
Unionide, 26, 147, 155 | Wheel animalcules, 7, 116 -
Univalve molluses, 138, 161, 167 | Whirligig beetles, 24, 334
Urodela, 363 | White water lily, 93
| Worms, 2, 6, 114

VALLISNERIA, 88
Valvata, 166, 168, 292 | YELLOW water lily, 98

PRINTED BY
SPOTTISWOODE AND CO,, NEW-STREE SQUARE
LONDON

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