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"This little book is quite up to date, and although scientifically accurate 
and sound, is so delightfully simple that it can be read and comprehended by 
anyone at the seaside who can collect common shore animals and compare 
them with the printed pages. It is a pleasure to cordially recommend Life by 
the Seashore as a charming and useful holiday companion, which will not only 
give much information, but Avill also serve as a good introduction to one of the 
most fascinating branches of modern science." Nature. 

"The present work can safely claim to have justified its appearance, for it is 
an exceedingly well written, and as far as it goes a very accurate account of 
the majority of the common animals found between tide marks." 

Journal of Queckett Microscopical Club. 

" This is a good book. After reading even the first chapter, one feels that 
Miss Newbigin knows and cares about her subject. The style and arrange- 
ment of the book are excellent ; there are numerous illustrations, and at the 
end of each chapter are tables of classification and a note on distribution 
which should prove extremely useful." Science Gossip. 

" As an introduction- to natural history it is admirable, and as a companion 
to a summer holiday by the sea it is invaluable." Weymouth Journal. 

First Published, 1901 : Reprinted, January, 1907 


book is largely based upon a series of lectures 
on common shore animals, delivered at different 
times to various audiences. Its object is to enable 
those who have not had a special zoological training 
to learn the names and characters of the common 
inhabitants of the rock pools ; but it is hoped that 
the subject has been treated from a sufficiently broad 
standpoint to render the book also of value as a 
general introduction to one of the most fascinating 
branches of modern science. Special efforts have 
been made to render the descriptions .sufficiently de- 
tailed to ensure the identification of actual specimens, 
and to assist the process by keys and tables. As this 
detail naturally limits the number of species it is 
possible to discuss, the book makes no attempt at 
completeness. It treats chiefly of the common shore 
forms of the East Coast, but this partiality is cor- 
rected, first by notes on distribution, and second by a 
list of books of reference, which will enable those 
interested to pursue the subject further. In regard 
to this list I may say that it has been limited to works 


in the English language, and to those readily accessible 
in the public libraries of our larger towns. 

As to the difficult question of nomenclature, I 
have in each group employed the names used in some 
standard work, indicated in the list of books of 
reference. Where these names are out of date a 
reference is given to a source from which the modern 
terminology can be learnt. Unless such valuable 
books as Gosse's Sea- Anemones are to be rendered use- 
less to the beginner, this seems the only possible 
course in a popular book. 

The figures, which I owe to my sister Miss Florence 
Newbigin, have in many cases been drawn from actual 
specimens; the source from which the others have 
been obtained is indicated in the list of illustrations. 
To my sister I am also indebted for the Index. 

EDINBURGH, June, 1901 







VI. THE BRISTLE- WORMS (continued] . ;. . 104 




X. THE TRUE CRABS . . . . 194 



XIII. THE SEA-SLUGS . . ... 248 

XV. FISHES AND SEA- SQUIRTS . . ..' . 290 


ANIMALS . . , 317 


INDEX 335 


*iG F/.OK 

1. Pholas crispata, a burrowing Mollusc ; 8 

2. Sand-laimce (Ammodytes tobianus). After Day . . 9 

3. Hermit-crab and Hydr actinia. After All man . . 12 

4. ZWo coronata. After Alder and Hancock . . . . 13 

5. Dead Men's Fingers (Alcyonium digitatum) . . 16 

6. Swimming-bell (Sarsia). After Allman . . . 17 

7. Lump-sucker (Cyclopterus lumpus). After Day . . 21 

8. Edible crab (Cancer pagurus) . . 26 

9. Plumularia sctacea. After Hincks . . .29 

10. Fisherman's lob-worm (Arenicola piscatorum) . . 30 

11. Common scallop (I'ecten opercularis) . 31 

12. Diagram of Hydractinia. After Allman . . .41 

13. Clava squamata. After Allman . . .45 

14. Syncoryne eximia. After Allman . 46 

15. Sarsia, or swimming-bell. After Hincks . 47 

16. Tubularia indivisa. After Allman . 49 

17. Obelia geniculata. After Hincks . 51 

18. Campanularia flexuosa (magnified). After Hincks . 52 

19. Halecium halecinum (magnified). After Hincks . . 54 

20. Sertularia pumila and branch magnified. After Hincks 55 

21. Bottle-brush coralline (Thuiaria thuia). After Hincks 56 

22. Plumularia (magnified branch). After Hincks . . 57 

23. Common sea-anemone (Actinia mesembryanthemum) . 65 

24. Tealia crassicornis. After Tugwell . . .68 

25. Sagartia troglodytes . . . 70 

26. Actinoloba dianthus. After Tugwell . 73 

27. Haliclystus octoradiatus . . 78 

28. Nereis pelagica . . . 84 

29. Foot of Nereis pelagica. After Ehlers . .' . 86 

30. Introvert of Nereis pelagica. After Lang . 87 




31. Dissection of Arenicola. In part after Gamble and 

Ashworth . . . *.. . 92 

32. Sthenelais boa, a sand Polynoid. After Johnston . . 97 

33. Paddle-worm (Pkyllodoce lamelligerd) . 99 

34. Head and introvert of paddle-worm. After Ehlers . 100 

35. Introvert of Nereis pelagica to show teeth. After Ehlers 104 

36. Foot of NepJithys hombergii. After Ehlers . . 109 

37. Sand-mason (Terebella) removed from tube . . 113 

38. Pectinaria belgica. After Malmgren . . . 115 

39. Serpula vermicularis in tube . ... 117 

40. Sea-snake (Linens marinus) . ... 121 

41. Solaster papposus, or sun-star . . . 128 

42. Common brittle-star (Opliiothrixfragilis) . . . 129 

43. Disc of sand-star (Ophiura) . . . 130 

44. Aristotle's lantern from sea-urchin . . .136 

45. Sea-urchin (Echinus esculentus) . ... 138 

46. Sea-cucumber (Cucumaria planci). After Bell. . . 144 

47. Prawn (Palcemon squilld) ' . . . 151 

48. Lobster (Homarus vulgaris) . ... 152 

49. Shore crab (Carcinus manias') . ... 153 

50. Foot-jaws of lobster and of crab . . .160 

51. Scaly Galathea (Galathea squamifera) . . . 177 

52. Hairy porcelain-crab (Porcellana platycheles) . .179 

53. Hermit-crab (Pagurus bernhardus) . . 184 

54. Masked crab (Corystes cassivelaunus). In part after 

Herbst . f . , "... 189 

55. Spider-crab (Eyas araneus) . . . .197 

56. Long-legged spider-crab (Stenorhynchus phalangium) . 198 

57. Wrinkled swimming crab (Portunus depurator) . . 202 

58. Megalopa of shore crab. After Brook . . . 206 

59. Mysis stage of Norway lobster. After Sars . . 206 

60. Opossum-shrimp (Mysis flexuosa) . . . 209 

61. Head and tail of Mysis. After Bell . . .212 

62. Idotea tricuspidata. In part from Bate and Westwood . 216 

63. Gammarus locusta . - . . . .217 

64. Caprella linearis . . . . . 218 

65. Sea-spider (Pycnogonum littorale) . . . 221 

66. Under surface of limpet (Patella) . . 226 

67. Chiton marginatus . . ... 228 

68. Tortoise-shell limpet (Acmcea testudinalis) . . 233 



69. Trochus zizyphinus . . ... 235 

70. Common whelk (Buccinum undatum) ' ' . . 244 

71. Sea-hare (Aplysia hybrida). After Gosse . , - .250 

72. Doris johnstoni. After Alder and Hancock , . 252 

73. Goniodoris nodosa. After Alder and Hancock . . 255. 

74. Aneula cristata. After Alder and Hancock .. . 256 

75. Spawn of Doto coronata. After Alder and Hancock . 259 

76. Eolis rufibranchialis. After Alder and Hancock . .261 

77. Common mussel (Mytilus edulis) j . . 267 

78. Tapes pullastra ., . ... 268 

79. Shell of Cyprina island,ica . . . 279 

80. Mactra stultorum .. . . . 280 

81. Mya truncata . . ... 283 

82. Kazor-shell (Solcn siliqua) . . . 284 

83. Corella parallelogramma . ... 292 

84. Polycarpa rustica . , . . 295 

85. Saithe, or coal-fish (Gadus wrens). After Day . . 298 

86. Sea-scorpion (Coitus scorpius). After Day . . 301 

87. Common shanny (Blennius pholis). After Day . . 306 

88. Gunnel (Centronotus gunnellus). After Day . . 308 

89. Herring-bone coralline (Halecium halecinum). After 

Hincks . . . ... 319 

90. Swimming-bell of Clytia johnstoni. After Hincks . 326 

91. Nauplius of Peneus. After Muller " . . .327 

92. Zoea of crab ( Thia polita). After Claus . . . 328 

93. Sea-gooseberry (Pleurolrachia) . ... . . 330 





Conditions of shore life The abundant food-supply The physical 
conditions Influence of the tides The peculiarities of shore 
animals Passive means of protection Shells and tubes The 
habit of burrowing Protection against organic foes Weapons of 
offence and defence Self-mutilation Partnerships Colour resem- 
blances Masking Dangers of storms and floods Means of dis- 
tribution Characters of young and larval forms. 

are perhaps few localities where the extraordinary 
_ abundance of life is more striking than on the seashore. 
From the birds which circle and cry overhead to the count- 
less myriads of sand-hoppers which spring up at every 
footstep, there seems to be life everywhere, life in a careless 
and wanton profusion the secret of which is known to the 
sea alone. Nowhere else does one find animals in such 
number and variety within a limited area. It is therefore 
all the more remarkable that while so many people take an 
interest in terrestrial animals, such as insects and land shells, 
relatively so few are interested in marine animals, where the 
field is so much wider, and the phenomena so much more 
striking. For every person who could name a common 
anemone there must be dozens who could name a common 
butterfly, and this in a country not a little proud of its 
encircling ocean. The opportunity for shore -hunting is 


nowadays given to very many people for at least a few 
weeks in every year, and even in this brief time it is 
possible to acquire not a little knowledge of the ways and 
structure of the common shore animals. 

We shall not at present seek strictly to define the mean- 
ing of the word "shore," but in beginning a preliminary 
study of the conditions of shore life, may conveniently start 
from that commonplace of observation, which shows that all 
parts of the shore area are not equally productive. It is 
true that wherever the ebbing tide leaves bare long stretches 
of sand, there will be found some of the inhabitants of the 
littoral waters, living or dead, according to the force of 
the waves which have torn them from their rocky homes ; 
but we all know that to find these animals in their natural 
conditions we must forsake the sandy beach for the weed- 
covered rocks. In order to understand why it is that the 
majority of shore animals live in the vicinity of rocks, let us 
watch what happens when some change of current uncovers 
a ridge of rock hitherto concealed by the sand. We find 
that the first organisms to appear are usually Algae of various 
kinds, the coarser kinds being often the most obvious at 
first. Then come acorn-shells and vegetable-eating Molluscs, 
and as these thrive and multiply they are followed by car- 
nivorous whelks, buckies, and starfishes. As the weeds 
grow, crabs and other Crustaceans make their appearance, 
and the new settlement thrives apace until it contains most 
of the animals inhabiting the parent area. How the 
animals reach the new area is a question to which we 
shall return later; our special concern now is what deter- 
mines the gradual colonisation, and why does it only occur 
where there is a solid substratum of some kind? The 
answer is simple; it is essentially a question of food, and 
the food upon which shore animals depend is most abundant 
in the vicinity of rocks. 

Let us for a moment consider generally the food-supplies 
of marine animals. The simplest case is probably that of 
the pelagic animals, or those animals which live in the open 
waters of the sea. These all depend ultimately either upon 
the microscopic plants with which the water is filled, or 
upon microscopic animals which because they contain green 
colouring matter are able to feed like plants. The depend- 


ence is primary when, as in many pelagic worms, molluscs, 
artd sea-squirts, the minute plants are actually taken as 
food ; it is secondary when, as in many fish, the food 
consists of the worms, molluscs, sea-squirts, etc., which 
themselves feed upon the Algse. Abundantly supplied with 
air and sunlight, the little plants grow and multiply rapidly, 
and constitute the great basal food-supply of the animals of 
the open sea. 

Many of those minute plants, or plant-like animals, occur 
also in the shallow shore waters, and there again constitute 
an important part of the food-supply, but this is supple- 
mented in two ways. First, we have an enormous amount 
of material carried into the sea by rivers. It is a fact of 
common experience that mudbanks of varying size usually 
occur about the mouths of rivers. The constituent mud is 
brought clown by the river, and it contains an abundant 
supply of nutrient material, of which very many shore 
animals avail themselves. Second, we have the large fixed 
seaweeds, which can flourish only in water shallow enough 
for the light to reach them, and which occur in great variety 
and abundance around our shores wherever there are rocky 
surfaces to which they can affix themselves. 

According to their diet we may divide the shore animals 
into three sets: (1) those which are vegetarian in habit, 
living upon the large seaweeds ; (2) those which feed upon 
minute food-particles contained in the water or in sand and 
mud ; (3) those which are carnivorous and depend upon 
the two preceding sets for food. All these three sets find 
food most abundant in the vicinity of rocks. The first 
obviously do so because the large seaweeds grow well only 
when fixed to a solid base. It may not be quite so clear 
why the statement is true of the second set, but it is a fact 
that shore animals which feed on microscopic particles are 
sedentary animals, not capable of resisting by their own 
activity the force of shore currents and shore waves. In 
consequence they usually cannot flourish unless, like the 
shore weeds, they have a firm basis of attachment. The 
chief exception arises in the case of burrowers which often 
live in sand quite away from rocks. As the carnivorous 
animals depend upon the preceding two sets, it is obvious 
that they can abound only in the vicinity of the rocks 


haunted by these. A little experience on the shore will 
soon convince you that shore animals are not quite so 
sharply differentiated from one another as regards food as 
this description seems to suggest, for some forms seem to 
indulge in a mixed diet; but at the same time it may be 
helpful at first to look at the food-supply in this way. 

So far we have seen that the shore area is above all 
distinguished by its abundant food-supply, but it must not 
be supposed on this account that life within this area is 
necessarily easy. It is indeed rather the reverse that is 
true. In the first place the abundant food-supply has led 
to a great increase of population, and a consequent increase 
in the intensity of the struggle for existence among the 
shore animals, and in the second place the physical environ- 
ment is so variable as to make heavy demands on the 
adaptability of the organism. Look at the wreckage which 
almost every tide strews upon the beach, and you will 
realise how fierce is the struggle against inorganic nature 
which goes on in the shore area. 

Let us look for a little at the special peculiarities of the 
physical environment of shore animals. Kound our coasts 
one of the most striking of the natural phenomena of the 
littoral region is the daily ebb and flow of the tide. Twice 
in each twenty-four hours the waters retreat and leave bare 
a great stretch of the shore, twice they return, the breakers 
thundering on the rocks as they advance. As everyone 
who has had anything to do with the sea knows well, not 
only does the extent of the rise vary according to the locality, 
but for the same locality it varies from day to day. Twice 
in every lunar month occurs the phenomenon of spring tides, 
when the water rises to an unusual height and sinks to a 
correspondingly low level. Even these spring tides are, 
however, not constant, certain tides in spring and autumn 
rising to a much greater height than the ordinary springs. 
Later, we shall discuss the importance of these facts to the 
naturalist, at present we are concerned merely with their 
importance to the shallow-water animals. The shore area is 
populated by truly marine animals from high-tide mark 
downwards ; indeed, certain periwinkles seem to live above 
the level of all but the highest spring tides. If we begin 
with these hardy forms and pass downwards to the region 


which is uncovered only at the lowest springs, we find a 
complete series of gradations in regard to exposure to air. 
The periwinkles mentioned are really under water only for 
a brief period daily, during perhaps a few days every six 
months. Then we may have other forms which are covered 
by water only for a short time at spring tides, and so on 
down to the animals which are wwcovered only for a brief 
period during the very lowest spring?. But, as all seafaring 
people know, the times and heights of the tides as indicated 
in the calculated tables are in many localities liable to 
considerable variation on account of winds and storms, so 
that one must? beware of ascribing too great constancy to 
tidal movements. All the animals which belong to the 
shore area, with a few exceptions which need not concern 
us here, breathe air dissolved in water, so that the fact that 
they are periodically exposed to the action of the atmosphere, 
necessitates special means of protection for the delicate 
breathing organs. The amount of protection required must 
necessarily vary with the amount of exposure. 

The risk of injury to the breathing organs is not the only 
danger to which the ebb of the tide exposes shore animals, 
for the removal of the water makes feeding impossible to 
not a few of them, and it also exposes them to variations of 
temperature the frosts of winter and the sun of summer 
and to the keen eyes of the birds which flock to the rocks 
as the tide ebbs. Furthermore, as the water returns its 
waves batter furiously against the rocks and their denizens, 
so that these have manifold dangers to guard against. 

Among the general characters of shore animals we should 
thus expect to find that they usually possess some means of 
protection against the risk of exposure to the atmc sphere, 
with the correlated risks of freezing or drying up, and 
also against the force of the waves, which tend to tear 
them away from their rocky homes. In point of fact, we 
do find that shore animals show many adaptations to these 
conditions of shore life. In the first place, very many of 
them possess shells into which the animal can retire, and 
which serve to protect it against variations of temperature 
and the risk of drying up. Shells are especially character- 
istic of the greater number of the Mollusca, or " shellfish " 
par excellence, but are also possessed by not a few other 


animals. Thus some worms, like Serpula and Spirorbis, make 
white limy tubes and shells into which the whole body can 
be retracted. The acorn-shells, which are often the common- 
est of all animals on the shore rocks, are Crustacea which 
secrete a limy shell into which the whole animal can be 
withdrawn, and which can then be closed to prevent evapora- 
tion of moisture. In these cases, however, the animals are 
completely sedentary, never moving from the place where 
they have settled down in youth, and from their size and 
shape offering little opportunity to the waves. It is other- 
wise with the Molluscs, which frequently possess consider- 
able power of movement, and have, as it were, to consider 
both the necessity of protection from drought and from the 
destructive force of the breakers. We are just beginning 
to understand the significance of the shapes of shells con- 
sidered from these points of view, and some of the more 
obvious adaptations only can be pointed out here. 

Most of the molluscs of the shore have either a shell 
composed of two valves, like cockles, mussels, and their 
allies, or have univalved shells like limpets, periwinkles, 
and whelks (Gasteropods). Among the latter the limpet 
represents the simplest though perhaps not the most primi- 
tive condition. Its shell is simply conical, and protects the 
dorsal region of the animal only ; but as everyone knows 
the limpet has extraordinary clinging power. The thick 
shell prevents loss of water by evaporation, the firm attach- 
ment prevents dislodgment by the force of the waves. The 
majority of the univalved Molluscs on the shore differ from 
the limpet in possessing a spirally coiled shell, which is 
often exceedingly thick and dense, and into which the 
whole animal can be withdrawn. Such forms as periwinkles, 
whelks, tops, dog-whelks and others do not cling like the 
limpet, but when alarmed or attacked often drop suddenly 
from their attachment. As they do so they withdraw com- 
pletely into their shells, and close the opening behind them 
by a shutter, or operculum, which exactly fits the orifice 
(see Fig. 70, p. 244). This done, the animal is completely 
encased and protected from extremes of temperature. The 
shell is so dense that the breakers do relatively little harm, 
even though the animals are rolled about roughly enough. 
It is believed that the shape and the sculpture of the shell 


are all of importance in giving strength to the shell, and in 
minimising the danger of rough usage. How successful as 
a protection the shell must be is demonstrated not only by 
the great abundance of periwinkles, whelks, etc., on the 
rocks, but also by the way in which they expose themselves 
to view when the tide ebbs, braving the dangers of frost 
and sun. 

The Bivalve shell seems on the whole less efficient as a 
means of protection, at least very few Bivalves live on the 
rocks in the exposed way in which the periwinkles and dog- 
whelks do. Some, like the mussels, grow in great colonies 
in sheltered places, very many live buried in sand, not a 
few burrow in rocks, but most are very liable to wholesale 
destruction in storms. As a rule the Bivalves have little 
power of locomotion ; they often spin a mass of silky 
threads, by means of which they anchor themselves to solid 
bodies, and which, as in the mussels, may constitute their 
chief defence against the force of the waves. 

Analogous to the habit of shell-making is the process of 
tube-building, which is carried on by hosts of worms. In 
most cases the tube consists of an organic substance secreted 
by the animal, to which are added foreign particles such as 
grains of sand, or fragments of stone and shell. Among 
the tube-building worms are the "sand-mason" (Terebella), 
a very common form, Sabellaria, a social worm, which builds 
sandy tubes, and many others. In many cases these tubes 
must be looked on as chiefly a means of protection against 
organic foes, but in other cases they are strong enough to 
protect the animal from the. dangers of its physical environ- 

By far the most effective method of protection against 
these dangers is, however, the habit of burrowing. A 
burrowing animal obtains protection from the waves, save 
in great storms; it obtains permanent moisture, a more or 
less even temperature, and finally is safe from the persecu- 
tion of most organic foes. The list of benefits is so long 
that it is no wonder that so many different kinds of animals 
have acquired burrowing habits. We can mention only a 
few of them. If you stoop under overhanging ledges of 
rocks, or turn over weed-incrusted stones, you may often see 
numerous holes in the rock, from each of which a red star 


protrudes. Touch these stars, and they instantly disappear, 
ejecting a feeble jet of water as they do so. If by means oi 
hammer and chisel you investigate the rock, you will find 
that the stars are the breathing-tubes or siphons of a little 
bivalved Mollusc, called Saxicava, on account of its rock- 
boring habits. The little creature remains permanently 
within its rocky burrows. When the rock is covered by 
water it protrudes its red tubes, and through them both 
feeds and breathes ; when the tide ebbs, or enemies threaten, 
it withdraws the tubes, and is safe. Another, and in some 
ways an even more interesting rock- 
boring Mollusc, is Pholas, of which one 
species is common in the soft fissile rock 
called shale by geologists. While walking 
over stretches of shale you may often 
notice that it is perforated by numerous 
round holes. When the rock is covered 
by water these holes are filled by a brown 
fringe, with some superficial resemblance to 
a sea-anemone. At a touch the fringes 
vanish like a shot. The shale is very soft, 
and can be readily pulled up in great 
blocks, when you will find that the holes 
are the openings of the burrows of Pholas, 
FIG. \.-Phoias crispata, a . wllite Bivalve, with a shell which gapes 
from under surface, to widely, and is beautifully toothed and 
tSSv!SKSi sculptured. In the Firth of Forth, where 
/, foot ; s, siphon. beds of shale are abundant, the rock is 
often simply riddled by Pholas burrows. Other species of 
the genus burrow in hard rocks, and are then much less 
easy to extricate. 

Far more numerous than the rock-borers are the burrowers 
in sand, which if it does not form so secure a resting-place 
as the solid rock is one more easily obtained, and is taken 
advantage of by many animals. Objection may be taken to 
the word "many," in view of the fact that children often dig 
in the sand for hour after hour, and yet rarely come upon a 
living creature. But the explanation is simple. Animals 
which burrow in sand almost invariably live on sand ; they 
can therefore only live in sand which is impregnated with 
organic particles. Such sand occurs usually in the vicinity 


of rocks or near the mouths of rivers, while in the long 
stretches of clean sand most frequented by children organic 
particles are remarkable for their absence. To illustrate the 
variety of sand-burrowing animals, I may give a list of the 
spoil taken by a party of which I was a member at some 
sands in the Firth of Clyde, near Millport. We got first 
a burrowing sea-anemone (Pe&hia), any number of heart- 
urchins (Echinocardium cordatum) covered with beautiful 
golden spines, Synapta, a curious pink worm-like creature 
really allied to sea-urchins, razor-shells (Solen), otter-shells 
(Lutraria), old maid shells (Mya), all living and active, any 
number of ringed worms of various kinds, some ribbon- 
worms, and many sand-eels, and all these occurred together 
within a very limited area, and were taken in the course of 
an hour's digging. 

FIG. 2. Sand-launce or sand-eel (Ammodytes tdbianus). After Day. 

One is tempted to say of each set of marine animals that 
they are the most interesting of all, but surely there is a 
special interest about sand-burro wers ! The worms, perhaps, 
one might pass over, for the common earthworm has 
familiarised us with the burrowing habit, but how does 
a sea-urchin get deep down into the sand ? Those mentioned 
above were found in one locality, living, not in sand, but 
in a sandy gravel full of stones and shells. The shell or 
test of the heart-urchin is as fragile as glass, so thin that 
unless held with care one's fingers go through it. How does 
it bore its way among sharp-edged stones without injury? 
So with many of the others, as the spade turns them up 
a dozen "hows" and "whys" crowd upon one. Digging 
in the sand may seem a childish pastime enough, but if you 
choose your sand aright it has many fascinations. 

There are many other of the more sedentary shore 
animals which do not burrow and are not protected by 
a thick shell. These usually settle down in damp and dark 
situations where the sun's rays do not penetrate, or they 


creep under stones and into chinks and fissures of the rocks 
as the tide ebbs, to seek protection both from sun and wind 
and from the keen eyes of the birds. It is in search of 
these that the shore-hunter diligently turns stones and 
creeps under overhanging rocks, where the weeds drip and 
the sea-squirts eject their tiny jets of water. Most of these 
are protected from the force of the waves by the fact that 
they are attached and sedentary, or by the shape of their 
bodies which makes it easy for them to lurk in crevices out 
of harm's way. 

There are still other ways in which shore animals may 
escape the dangers associated with the ebb and the flow of 
the tide. Thus they may avoid these dangers by their own 
activity, following the water as it ebbs seaward, and return- 
ing with it when it once more flows landward. These are 
best represented on the shore by some of the Crustacea 
such as prawns, some shrimps, various kinds of lobsters 
and by certain fishes. In both cases, however, the power 
of active swimming is comparatively rare in truly littoral 
forms, probably because the strong shore currents make it a 
danger rather than an advantage. Thus, of the shore fishes, 
the blenny (Biennius pJiolis) remains lurking under stones 
often quite uncovered by water, the sand-eels (Ammodytes 
tobianus) often bury themselves in the sand, where stickle- 
backs (G aster osteus) are also at times to be found. Among 
the shore Crustacea, as we shall afterwards see, there is 
evidence that in the higher forms the power of swimming 
has been gradually lost, and the animals have been adapted 
for life at the bottom and on the tidal rocks. This has been 
accompanied in the crabs by a modification of the dorsal 
shield or carapace, which has for its object the protection 
of the gills from the risk of drying up. So carefully are 
these protected in many crabs that the animals can live for 
a long period out of water. In some cases, indeed, as in the 
common shore crab, an exposure to air during a portion of 
the day seems actually beneficial. While very many Crus- 
tacea and a few fishes are thus rather to be reckoned among 
the forms which lurk passively in hiding when the tide 
ebbs, there are still a considerable number who are active 
swimmers, and constitute the "floating population" of 
the rocks. The capture of these can only be hoped for 


when they are trapped in some rock pool by the ebbing 

The above brief account of the way in which animals 
protect themselves against the dangers of their physical 
environment may serve as an outline which your experience 
in actual collecting will later enable you to fill up. We 
may now look for a little at the ways in which the shore 
animals protect themselves from their organic foes. In 
some cases, as we have already seen, the same artifice which 
protects an animal from the one set of dangers protects it 
from the other. The fisherman's lob-worm (see Fig. 10, 
p. 30) is greatly relished by very many fish ; we can hardly 
doubt, therefore, that it is, in an ordinary way, protected 
against these by its burrowing habit. Most tube-worms 
vanish into their tubes instantly at the least alarm, often 
merely at a shadow. It is reasonable to conclude that the 
tube affords a natural protection. It is not very uncommon 
on the shore to find mutilated whelks, which have apparently 
had their anterior region bitten off by fish before they had 
time to withdraw into the shell ; a fact which again suggests 
the protective value of the shell. Facts of this kind might 
be multiplied indefinitely, but the protective value of hard 
shells is in the general case sufficiently obvious, and we may 
pass on to less familiar means of defence. 

Many shore animals seem to be protected by their 
weapons, whether of offence or defence, or by some un- 
pleasant attribute. Thus the great pincers of crabs and 
lobsters make them dangerous adversaries ; jelly-fish and 
sea-anemones are protected by their stinging-cells; sponges 
are often full of sharp spicules ; many worms have an 
elaborate armature of bristles; and so on. The power of 
self-mutilation, or autotomy, is also widely spread among 
shore animals, and must often assist their escape. Most of 
the shore crabs, if seized by a limb, will throw off the limb 
and escape. Brittle-stars break their rays at the slightest 
touch, and the separated portion keeps up active movements 
for some time. Not a few "worms" throw off gills or 
tentacles or other portions of the body when molested. In 
this case the separated organs move about even more actively 
than when attached, and doubtless distract the attention of 
the enemy. In all cases where autotomy is practised, the 



animals possess the power of renewing the parts thrown off. 
Almost as curious as self -mutilation is the habit of 
"shamming dead," which is practised on the shore by 
many Crustacea, just as it is on land by many insects. 
Sand-hoppers and the common shore crab may be mentioned 
as artists in this subterfuge. The habit doubtless saves 
them from the attacks of animals which confine their 
attention to moving prey. 

Again, not a few animals seek safety in the companionship 
of other stronger and better protected animals. Examples of 
this are abundant on the shore. Thus the common hermit- 
crab often shelters a worm (Nereis fucata) within its shell, 
which no doubt finds the hermit's claws and borrowed house 
a protection against some foes. The hermit-crab of the 
West carries about with it an anemone (Adamsia) which 
throws out a quantity of stinging threads, and thus perhaps 
protects the hermit from attack, while the common hermit- 
crab often has its shell covered by a luxuriant growth of 
possibly defensive zoophytes. 

FIG. 3. Hermit-crab with the shell covered by a zoophyte colony 
(Hydractinia echinata). After All man. 

A pretty little Bivalve (Modiola) lives habitually within 
the tough tunic of sea-squirts, while a still more enterprising 
little Crustacean actually lives inside the body of the sea- 
squirt. Within the shells of the horse-mussel and some 
other Bivalves, there may be often found a little soft-shelled 
crab, which finds there the protection its soft coat cannot 


give. These are only a few examples of partnership or 
symbiosis, which is a common phenomenon among shore 
animals. It is very apt to degenerate into parasitism, where 
the one partner not only gets house room, but actually lives 
upon the host. 

We have seen that the shell of shellfish affords an 
apparently efficient protection against many dangers, but it 
is important to note that not a few Univalves have entirely 
lost their shells. These constitute the forms known as sea- 
slugs, sea-lemons, and more generally as Nudibranchs, or 
" naked-gilled " forms. Many of these occur on the shore, 
and though on account of the absence of any means of 
protection against drought they are confined to the zone 
near low-tide mark, yet there they are abundant enough. 
Many of them are very brightly coloured, and most are 
furnished with little processes, either simple or branched, 
which decorate the back, and add greatly to the beauty. 

FIG. <i.Doto coronata, a sea-slug with the back ornamented with curious 
branched processes. After Alder and Hancock. 

In spite, however, of the frequent conspicuousness of the 
animals, and the absence of any protective shell, there can 
be no doubt that they are very rarely attacked or eaten by 
the other shore animals. Many naturalists believe that the 
bright colours and conspicuous processes are an advertisement 
of inedibility, like the vivid colouring of some inedible 
caterpillars. It is interesting to note, on the other hand, 
that while many Nudibranchs are conspicuous and highly 
coloured, others are exceedingly like, the weeds and corallines 
among which they live. Thus Doto coronata (Fig. 4), a 
beautiful and not uncommon sea-slug, is very like the 
common coralline, or pink limy weed, and is exceedingly 


difficult to distinguish from the coralline. There seems no 
reason to helieve that such "protectively" coloured forms 
are edible any more than the conspicuous forms, and they 
do not attack active prey ; so that the use of the particular 
coloration does not seem very clear. It is, however, certain 
that a close resemblance between organism and surroundings 
is a very common characteristic of shore animals, and doubtless 
often conceals them from their enemies, and enables them 
to steal unperceived upon their prey. In not a few cases 
the coloration is variable, changing with the surroundings. 
As groups in which this phenomenon may be looked for we 
may mention Crustacea, such as crabs, shrimps, and their 
allies; fishes, such as flounders, plaice, etc.; and even anemones, 
such as the "cave-dweller" (see Fig. 25), Sagartia troglodytes, 
whose colour varieties seem to show a relation to its sur- 

In connection with this same subject we may notice the 
habit of " masking " themselves which is displayed by many 
Crustacea. Practically all the different kinds of spider- 
crabs are found to have the back and legs covered by a 
more or less thick coat of weed or zoophytes. These are 
actually attached by the crabs themselves, as may be readily 
seen in captivity, and are fastened on by very curious 
hooked hairs with which the bodies of the crabs are covered. 
The common Hyas araneus (see Fig. 55) of the East Coast 
may be specially mentioned as a spider-crab which goes 
about elaborately masked. Another form, Inachus dorset- 
tensis, which lives in deeper water, shows a decided 
preference for sponges, and is often found with back and 
legs covered by masses of it. Curiously enough, the sponge 
itself often has its interstices filled with the muddy burrows 
of a little Crustacean (one of the Amphipods), which is at 
times present in great numbers. 

These cases of "masking" pass by insensible gradations 
into true symbiosis, where there is a constant association 
between two animals, as in the cases noted above. 

There is one danger to which shore animals are subjected 
which we have not as yet noticed, because although 
doubtless they have acquired means of protection against 
it, yet the adaptation is physiological, that is, a matter of 
function, and cannot be studied as readily as a morpho- 


logical or structural characteristic can be. This is the 
danger associated with a possible influx of fresh water into 
the shore area. In most cases where the shore is fringed 
by a long stretch of rocks, these rocks are interpenetrated 
by fresh-water streams, and the animals in the neighbour- 
hood of these streams are liable to be overwhelmed by 
floods. On a larger scale, rocks in the vicinity of rivers 
are similarly liable to the influx of large bodies of fresh 
water. As is well known, many fish are not only indifferent 
to the contact of fresh water, but at the breeding season 
actually court it. Among those which can alternate from 
fresh to salt water without danger are the salmon, eels, 
sticklebacks, and others. Not a few fish, again, are ex- 
tremely sensitive to the action of fresh water, which seems 
to produce an almost instantaneous paralysis. Among the 
lower animals a good many of the Crustacea and some 
shellfish or Molluscs haunt estuaries or the neighbourhood 
of streams, and are indifferent to the presence of a consider- 
able amount of fresh water. In the vast majority of cases, 
however, especially in the case of animals without shells, 
fresh water acts as a powerful poison. This is especially 
interesting, because we know that the salinity of sea water 
varies greatly ; thus the Mediterranean is very dense, while 
the Baltic contains a very much smaller portion of dissolved 
salts, and yet some animals inhabit both areas. Experiment 
shows that while an animal will not support direct trans- 
ference from one of these media to the other, it can be 
gradually educated to do this, if the changes are made 
sufficiently slowly. Part of the interest of the shore area 
is that it affords constantly varying conditions of life, the 
variations under ordinary circumstances being small enough 
to allow the animals time to adapt themselves to the new 
conditions. It is because of these constant variations that 
evolution has proceeded so rapidly in the area. 

One other general point must be considered, and that is 
the way in which the animals of the shore area are dis- 
tributed. In the preceding pages some attempt has been 
made to indicate the vicissitudes of shore life, and to suggest 
the great variety of conditions which may prevail there. 
One consequence of this is that particular shore animals are 
often very local in their distribution. Obviously an animal 



which is adapted for life in mud must be confined to areas 
where mud-beds occur, and thus be absent from long 
stretches of shore. But apart from simple cases of this 
kind, it often happens that an animal whose adaptation 
to some special condition of life is not very obvious, is yet 
confined to certain localities, and is absent from intervening 
places which are apparently equally suitable. Thus the 
beautiful Alcyonium (Dead Men's Fingers) only occurs 
sporadically between tide marks, probably in part because 

it offers little resistance 
to wave action, and re- 
quires peculiarly shel- 
tered spots for fixation. 
Again, the Plumose 
anemone (Actinolola 
dianthus, Fig. 26, p. 73), 
one of the finest of our 
British anemones, is on 
the East Coast at least 
a very local form, some- 
times occurring in great 
beauty and profusion in 
one particular spot only 
in a large bay. Many 
other examples might 
be given, but without 
labouring the point, we 
may say generally that 
although it is an advan- 
tage for .adult shore 
animals to be firmly 
fixed, or to be able to offer passive resistance of some sort 
to wave action, yet it is also highly desirable that they 
should at some period of life possess sufficient power of 
movement to enable the species to be carried to fresh 
localities, and suitable localities may be a considerable 
distance away from the home of the parents. In point 
of fact, almost all shore animals produce minute active 
young, which usually live near the surface, and are eminently 
well adapted for transport by currents or by their own 
activity. One of the most interesting subjects of study 

Fio. 5. Dead Men's Fingers (Alcyonium digi- 
tatum), a colony of small polypes. 


on the shore is the life-history of the common animals, 
and the peculiarities of the young forms. In some cases, 
as in the sea-firs or zoophytes, there is what is known as 
alternation of generations, that is the occurrence in one 
life -history of two or 
more different forms, 
differently produced. 
Thus, the sessile sea-fir 
buds off a little swim- 
ming-bell or tiny jelly- 
fish, which produces 
the eggs from which 
new sea-firs arise. As 
the swimming-bells can 
move actively through 
the water, and are also 
very readily swept along 
by currents, it must 
often happen that the 
eggs are deposited some 
distance away from the 
original sea-fir colony. 
Most worms produce 
eggs which give rise to 
minute top-shaped Iarva3, 
which live near the sur- 
face of the water and 
ensure the distribution 
of the species. Even 
the sluggish Echino- 
derms, the starfish, sea- 
urchins, and brittle-stars, 
produce minute active 
larvae, which present 
no apparent resemblance 
to the adult, and are 
adapted for quite a 
different kind of life. 
But it is among the Crustacea that we have the most 
complex and interesting life-histories. In them there is 
not merely one peculiar larval form, but the young undergo 

Fio. 6. Swimming-bell (Sarsia) of a sea-fir, 
showing the long tongue, or manubrium, 
swollen by the contained eggs, and the 
four long tentacles which bear stinging- 
cells. After Allman. 


a succession of remarkable changes before they attain the 
adult form. Our present interest in these cases is due to 
the fact that the peculiarities of the larvae ensure the dis- 
tribution of the species, and compensate for the limitations 
of that sedentary life which the exigencies of shore life 
force upon so many of the adults. But we shall see later 
that these Iarva3 are also of great interest in possibly 
throwing light upon the origin of the animals of the sea- 
shore, and upon their relations to the animals of the other 
parts of the ocean. 



Where to begin How to begin The study of common animals 
Characters of limpets Their structure and habits The common 
crabs and their characters Classification of shore animals 
General hints as to methods. 

WE have in the preceding chapter considered in outline 
the special nature of the surroundings among which 
shore animals pass their lives, and the nature of the adapta- 
tions by which they respond to the peculiarities of these 
surroundings. In this chapter we have to consider how the 
would-be naturalist is to become acquainted with the teem- 
ing life of the seashore. The first question to be asked is, 
Where shall we begin 1 ? It is obvious from the foregoing 
that except where the luxury of a dredge is available the 
field of action must be the tidal rocks. It is true that the 
mud-flats at the mouths of rivers and streams may furnish 
many different worms, some burrowing sea-urchins and sea- 
anemones, cockles, mussels, and razor-shells; and the streams 
themselves may abound with shrimps, sand-hoppers, sand- 
eels, shore crabs, and other hardy creatures; yet, alike for 
accessibility and for wealth of types, the rock pools claim 
pre-eminence, and it is with them that it is advisable to 

It is probable that the question, Which rocks 1 will often 
be determined by other causes than the naturalist's predi- 
lections, but it is nevertheless worth while to point out what 
conditions are especially favourable. For my own part I 
should be inclined to regard as the most important requisite 
that of ready accessibility. Where pools of considerable 
depth are within easy reach of the shore, the observer may 



hope for a tolerable harvest of some kind. There is un- 
doubtedly great variation in the number, both of indi- 
viduals and species, obtainable even in places not far distant 
from one another, and this is especially true in regard to the 
wreckage flung upon the shore. It not infrequently happens 
that the set of the current brings treasures to one perhaps 
small area of a bay, which may elsewhere yield little or 
nothing even to careful and long- continued search. To 
those beginning the subject, however, these waifs and strays 
must rank second to living forms whose habits may be 
watched from day to day, and for these we must seek the 
rocks. A famous horticulturist once said that the best 
advice he could give the amateur was to like what he could 
grow, if he couldn't grow what he liked. Similarly, the 
shore naturalist may be advised to interest himself in the 
animals he finds, if he cannot find those in which he is 
interested. There are few rocks so barren as to yield 
nothing to the industrious hunter, and in the general case 
the statement that a particular area is unproductive, and 
its pools void of life, is more likely to be based upon in- 
efficient observation than upon fact. Hopefulness is indeed 
justified even where the surroundings seem adverse in the 
extreme. I have found brilliantly coloured specimens of 
the sea-anemone, Anthea cereus, in company with many 
Nudibranchs and rare Annelids, on rocks which I was 
assured on good authority were hopelessly poisoned by 
drainage from lead mines. In the Firth of Forth colonies 
of Alcyoniam in perfect health and beauty may be found 
within a few yards of a shore piled with the accumulated 
nastiness of our civilisation, and similar examples might be 
multiplied indefinitely. Nevertheless, as a slight guide to 
those whose choice of a summer resort is unhampered, a 
brief list of places famous for their shore animals is given 
at the end of the chapter. 

While, however, we recognise in this way that there are 
few patches of rocks which are not worth a hunt, it is well 
also to consider under what conditions there is likely to be 
"good hunting." In the first place it is important to realise, 
what we have already dwelt upon, that few marine animals 
like the full glare of the sun, and fewer still the danger of 
drought. Now the tide ebbs and flows twice a day, and 


with a spring tide the water may drop a vertical height of 
up to forty feet; so that it is obvious that unless the moisture- 
loving animals can allow for the periodic movement of the 
waters, they must be very liable to elimination either by 
direct drying up, or by exposure to the keen sight of the 
birds who follow the receding waves. So far as we know, 
the tide has always ebbed and flowed, wherefore the shore 
animals have had time to learn their lesson. The result 
is that sedentary animals like sea-anemones, sea-squirts, 
Alcyonarians, sea-firs, and the like establish themselves 
only under overhanging rocks or in deep crevices where, 
even when the waters retreat, there is a grateful coolness 
and moisture, and a refuge from keen eyes. Sluggish forms, 
like many Annelids, the ribbon- worms, the starfishes and 
brittle-stars, sea-slugs, and many more which are equally 
unable to follow the water, and equally unwilling to be 
deprived of moisture creep into similar situations or under 
stones and weed, to pass their time of waiting; and there 
are left exposed a few hardy forms only, with some special 
means of minimising the risk of drying up. Finally, at every 
tide, but more especially at the springs, certain active forms 
are prevented by untoward circumstances from escaping with 
the ebbing water, and are held prisoners until it comes again. 

FIG. 7. Lump-sucker (Cycloptenis lumpus). After Day. 

Among such are many fish, lump- suckers, gobies, stickle- 
backs, sea-scorpions, and others; at certain seasons of the 
year the large cuttles, various Crustacea, and many other 
curious creatures. If these facts are borne in mind, it will 
be obvious that rocks are most likely to yield a rich harvest 


when they are deeply fissured and hollowed out, leaving 
many shady corners and deep pools ; for in the former the 
sedentary forms will be found, while the latter act as traps 
to the floating population. It is not, however, sufficient that 
pools and fissures should exist : there must also be ready 
access to them. In the case of stratified rocks readiness of 
access depends largely upon what geologists call the dip. 
The ideal case is, perhaps, that where the rocks run out to 
sea in long ridges of which each stratum overhangs its 
neighbour, while between successive ridges are long channels 
whose contents are available until the tide actually covers 
the ridge. When, on the other hand, the rocks dip outwards 
to the sea, these same channels form dangerous pitfalls to 
the too enthusiastic naturalist, who lingers on the distant 
ridges regardless of the eddying currents which are cutting 
off his retreat. This danger is sufficiently real to make it 
decidedly worth while to take a general survey of the rocks, 
and study their peculiarities before beginning serious work. 

This done, there still remains one more point to settle, 
and that is the part of the rocks to which our energies are 
to be devoted. Broadly speaking, there are two possibilities 
the strictly littoral rocks, those which are exposed at 
ordinary low tide, and are only completely covered for a 
relatively brief period about the time of high tide ; and the 
Laminarian zone, which is only accessible for a short time at 
extreme low water during spring tides, and then only in 
part. It is in the pools sheltered beneath the long fronds of 
Laminaria, or oar-weed, that the greatest treasures are to 
be found the tiny Eolis coronata, with its brilliant colour- 
ing in blue and crimson; the active Galatheas, darting back- 
wards through the pools; the larger Annelids, with their 
bright pigments and gleaming iridescence, and many others 
but the time during which these pools are accessible is 
woefully brief, and the beginner is recommended to confine 
himself, at least at first, to the rocks nearer the shore. 

Let us suppose ourselves, then, ready to start for an 
introductory expedition to the rocks. First, as to the 
equipment, let this be as simple as possible ; the danger lies 
not in collecting too little, but in the general case in 
attempting too much. According to my experience the 
average beginner provides himself with numerous buckets 


or bottles, and arriving at the rocks proceeds to transfer into 
these all the animals and pretty pieces of weed which catch 
his eye. On returning home the spoil is placed in some 
corner until the weary traveller is rested, is then forgotten, 
and remains neglected until it ceases to be an object of 
delight, and is finally thrown out by the irate housemaid, 
the net result to all concerned being usually an impression 
that the study of marine zoology is associated with odours 
of a powerful and unpleasing nature. It is impossible to 
speak too strongly of that collecting instinct which leads 
people to gather together all that they see, regardless of the 
fact that they are leaving the world poorer for their neigh- 
bours. Wherefore I would beseech the would-be naturalist 
to think always of him that follows after. 

If the mere accumulation of specimens be discouraged, 
the question of how to begin remains unsettled; the oft- 
repeated advice to study the habits of animals, like many 
similar pieces of advice, not being of great practical value. 
The way which is likely to lead in the long run to the best 
results is probably to attempt first to acquire some know- 
ledge of the commonest forms, and then later to utilise the 
powers of observation which have been trained in this way 
in a search for rarities. A detailed study of internal anatomy 
is in most cases very difficult for those without previous 
training, but a knowledge of external form is not to be 
despised, and is readily acquired. 

For example, any rocks will probably exhibit even to the 
most casual observer such animals as limpets, crabs, and 
various kinds of shrimps. Take the limpets first. The 
most abundant form will be the common limpet (Patella 
vulgata), but in Scotland or the North of England the tor- 
toise-shell limpet (Acmcea testudinalis) is almost as common. 
Far out on the rocks the transparent limpet (Helcion 
pelluddum) will be found creeping over the great fronds 
of oar-weed, and so on; the list might be extended to 
considerable length, according to the locality. Now there 
can be no better exercise, or more fitting introduction to 
zoological study, than to choose two or more of these forms, 
and study them until they can be recognised at a glance. 
This may seem an easy task, but experience shows that it 
is not so. At one time, when making some observations 


on the tortoise-shell limpet, I attempted on several occasions 
to get assistance in collecting specimens. The result was, 
however, invariably that I was presented with young speci- 
mens of the common limpet, with the assurance that these 
were exactly the right thing. 

The differences are nevertheless well marked. In the 
common limpet the thick shell is marked with ridges 
which project at the margin of the shell; in the other the 
surface of the shell is perfectly smooth, and marked with 
a beautiful "tortoise-shell" pattern in brown. In the 
common limpet the inside of the shell is glassy smooth 
and transparent; in the tortoise-shell it is opaque white, 
except for an elongated brown mark in the upper part. 
Between the animals themselves the differences are much 
more marked, as will be readily seen by putting both into 
a glass bottle and allowing them to crawl up the side. In 
the flattened creeping sole or foot, in the pendent fringe 
or mantle-skirt surrounding this foot, in the horns or ten- 
tacles at the sides of the prominent mouth, there is marked 
resemblance; but in Patella the side of the mantle next 
the foot is pleated and vascular, forming the breathing 
organ of the animal, while as the little Acmcea moves you 
will see it protrude in front a single plume-like gill. As it 
creeps up the glass, also, you will notice that its mantle is of 
a delicate green colour, while that of the common limpet is 
dull-coloured ; the whole animal has also a delicate trans- 
lucency beside which the common limpet seems coarse and 

In habitat there is also a marked difference. At low tide 
the common limpet is found far above the water level, with 
its shell embedded in a slight excavation of the rock into 
which it closely fits; the tortoise-shell, on the other hand, 
is rarely found except in pools. The little pits which the 
common limpet makes and inhabits, together with its tre- 
mendous power of adhesion, must diminish the evaporation 
of moisture, and therefore diminish the risk of drying up ; 
the thick shell probably also aids in the retention of the 
necessary water. If you knock a living limpet off the rock 
you will find that the under surface is abundantly moist, 
while the specimens which have been knocked off by the 
birds and left foot upwards seem to dry directly. The 


tortoise-shell limpet does not fit nearly so closely to the 
rock, its shell is much thinner, and its tissues more delicate ; 
it is probably for these reasons that it never leaves the 
pools. It must, of course, be realised that both are true 
aquatic animals, and that a certain amount of moisture is 
an essential of existence to both. The difference between 
the power of adhesion of the two forms is so marked that 
it can be employed as a means of distinguishing them where, 
from depth of water or other cause, the characters of the 
shell cannot be clearly seen. As everyone knows, the com- 
mon limpet may be dislodged by a sudden and unexpected 
blow ; but if the first attempt fail, the alarmed animal 
adheres so tightly that a knife is necessary to detach it. 
The tortoise-shell limpet, on the other hand, can always be 
removed with the fingers alone. It never reaches the size 
which the common limpet does, but in specimens of the 
two forms of the same size the difference in the clinging 
power is quite distinct. 

This description should be sufficient to permit of an easy 
recognition of the two forms, and they should be studied 
until eye, touch, and muscular sense are so trained that there 
is no possibility of error. This may seem a trivial occupa- 
tion, but some preliminary training of this kind is essential 
to anyone desirous of acquiring an acquaintanceship with 
species; and the identifying of species, though now sadly 
out of fashion, is an occupation which may yield one of the 
subtlest of pleasures. Of late years so much has been said 
of variation and its consequences, that not only the general 
public, but even some zoological students, seem to have an 
idea that species were something abolished by Darwin, and 
that the notion that there is constancy and orderliness in 
nature is a mediaeval myth. It may well be that the older 
naturalists made too much of that constancy, and toiled 
over their species-mongering until they reduced the organic 
world to the condition of a labelled liortus siccus instead of 
a living, growing reality ; but it does not appear that our 
gain is great if we swing to the opposite extreme, and 
inculcate the idea that there is no constancy or definiteness 
in nature at all. So much of the present-day academical 
teaching seems to have this result, that I cannot but urge 
anyone beginning open-air studies to find some time for 



species work, and for this habits of patient and minute 
observation are essential. It is necessary, also, to emphasise 
the necessity for handling specimens freely. The healthy 
child instinct to touch everything seen is so thoroughly 
educated out of most people, that they never seem to realise 
how enormously sense impressions are strengthened when 
hand and eye work in combination. In studying zoology, 
therefore, from the first train your fingers. 

The preliminary study recommended in the case of 
limpets may be equally well carried out with the different 
kinds of crabs. The hard coat of the crabs, which gives 
perfect consistency to the form, renders them particularly 
well fitted for the present purpose. On every shore two 
kinds of crabs are almost certain to be found : these are 

the common shore crab 
(Cardnus mamas, see 
Fig. 49, p. 153), and the 
edible crab (Cancer 
pagurus}. The former 
on the tidal rocks will 
be found most in evi- 
dence, but small forms 
of the latter are usually 
very abundant, especi- 
ally far out, and those 
who know where to 
look will not fail to 
find examples of quite 
considerable size. The 
young of the shore crab are extraordinarily variable in colour 
they change, indeed, according to their surroundings 
while the colours of the young edible crabs are much more 
constant, though often quite unlike those of the adult. It 
is not necessary to discuss in detail the differences between 
the two forms ; there are probably few people who could not 
recognise an adult edible crab when they see it. Unless, 
however, your perception of form is much stronger than 
your perception of colour, you will probably find that the 
colour variations of the young confuse your judgment, and 
that you have some difficulty in settling the nature of a 
handful of small crabs gathered at random. If this is so, 

FIG. 8. Edible crab (Cancer pagurus). 


the best plan is to take fair-sized specimens of the two 
forms and compare them point by point. You will notice 
at once that, just as in the case of the limpets, there is 
much general resemblance. In all the essentials of structure 
the two are similar, but there is nevertheless a well-marked 
difference. Study the two until you can say precisely 
wherein the difference lies (the shape of the dorsal shield, 
or carapace, and of the numerous legs will be found 
especially important), and then return to the young speci- 
mens. If your analysis has been careful you will find that 
the difficulty has vanished, and that you can now sort your 
specimens without fear of error. 

There are many other common animals which can be 
similarly employed as a means of strengthening the percep- 
tion of form in animals, and such introductory training will 
be found of much value afterwards. It will also serve to 
familiarise you with the haunts and habits of the common 
types, a point of much importance. As, however, your 
acquaintance with the rocks and their inhabitants increases, 
you will find the need of a classification of animals a 
method of pigeon-holing your too numerous facts. We shall 
therefore consider next an outline classification. 

The first point to notice is that the fauna of the rocks is 
so abundant and so varied that, among Invertebrate or back- 
boneless animals at least, there are few great groups which 
are not numerously represented. The sea, the fruitful 
mother of all things, retains representatives of most of her 
children within herself. In spite, therefore, of the fact that 
our classification is professedly based on marine forms only, 
we shall find few important blanks in it. 

Lowest of all, and including forms with which we shall 
not concern ourselves much here, are the PROTOZOA, the 
primitive unicellular organisms, resembling those from which 
all others have originated. Consisting as they do of single 
cells, or of colonies of cells in which the units are not 
dependent upon one another, it will be readily understood 
that the Protozoa are mostly minute, often excessively so. 
Many forms, however, make shells of lime or flint, and may 
by their abundance give rise to considerable deposits. Such 
Protozoa helped to form the chalk of the South of England, 
and are forming the oozes (Globig&rina ooze and Radiolarian 


ooze) which are at present accumulating on the floor of the 
ocean. Protozoon shells may be found among shell-sand on 
the rocks, but the Protozoon which is most likely to be 
encountered without special search is the little Noctiluca, 
the chief cause of the occasional li phosphorescence " of our 
seas. It is just visible to the naked eye, and in the dark 
appears like a tiny point of light. Into the characters of 
the Protozoa we shall, however, not here enter in detail. 

The next great class of animals includes much more con- 
spicuous forms the SPONGES, long thought to be plants. 
The familiar bath sponge is, of course, merely the skeleton of 
a once living animal, or rather of a collection of individuals, 
a colony of sponges. For an example of a simple sponge 
you should look under overhanging ledges of rock, and you 
will find a little sac of dull colour and compressed form 
hanging downwards. One end is fixed to the rock, the other 
terminates in an opening which is not a mouth, for nothing 
enters by it, but which serves as a means of exit for the 
currents of water which enter the central cavity by numerous 
pores in its walls. This central cavity is simple and un- 
. divided ; there is no alimentary canal, and no organs, the 
sponge is merely a thin-walled sac, lined with cells bearing 
motile threads or cilia, which by their movement produce 
continuous currents. Without power of locomotion, with but 
little feeling, and no active means of defence, the sponges 
would not be able to survive as they do were it not that they 
are passively protected by their power of forming a skeleton. 
This skeleton may be composed of sharp spicules of lime or 
flint, or of silky fibres, as in the bath sponge, but in all 
cases it seems to render the sponges ugly mouthfuls, and so 
induces most animals to let them severely alone. In addition, 
many sponges have a strong odour. Many are brightly 

The little purse-sponge (Grantid), described above, has 
usually a single large opening, .through which water leaves 
the central cavity ; but many sponges, like the bath sponge, 
or the very common crumb-of -bread sponge found on the 
shore, have many of these large openings ; in the crumb-of- 
bread sponge they stand up on the flat surface like little 
craters. As each opening represents an individual, such 
sponges are really colonies, formed by budding from an 


originally simple individual. Very many sponges are in 
this way colonial. 

Above Sponges, but still forms of very simple structure, 
are the CCELENTERA, or hollow-bodied animals sea-anemones, 
corals, sea-firs, "dead men's fingers," jelly-fish, and many 
others, almost all beautiful in form and colour, and with a 
delicacy and fragility which makes it essential that they 
should be studied in the living condition. They agree with 
Sponges and differ from higher animals in 
containing one central cavity only, instead 
of having an alimentary canal inclosed 
within a general body-cavity. They have, 
however, a true mouth surrounded by 
tentacles, instead of the numerous pores 
of the Sponges; the skin, especially on 
the tentacles, contains offensive and de- 
fensive stinging-cells which can be ejected; 
there is often a skeleton of lime or some 
other substance; their symmetry is radiate, 
like that of a flower. Many of the Cos- FIG 9. 
lentera are colonial, and it is such colonial Hi*^d"k' Ooeofttie 
forms which build up the coral reefs of sea-ihs. 
warm seas. 

Above the Coelentera we come to the UNSEGMENTED 
WORMS, animals not nearly related to one another, but all 
differing from the Coelentera in having distinct anterior and 
posterior regions a distinction of head and tail, in having 
a separate alimentary canal within the general body-cavity, 
which may, however, be largely filled up, and in the greater 
complexity of their structure. Among these we shall be 
concerned only with certain little flat-worms called Turbel- 
laria, and with the ribbon-worms (Nemertea). 

Much more highly differentiated, but sometimes loosely 
included under the heading of " worms," we have the 
SEGMENTED WORMS, or ANNELIDS. In them the body is 
divided into successive rings, or segments, of similar struc- 
ture, which usually bear locomotor organs furnished with 
bristles. There is a well-developed body-cavity, which 
opens to the exterior by little coiled tubes, or nephridia, 
structures of much importance to the morphologist. The 
Annelids which are especially adapted for a marine life 



(Polychseta), are very numerous, and include many interest- 
ing and beautiful forms. To them we shall return at 
length. They are recognised by the 
elongated segmented body, and the 
' p lateral tufts of bristles. 

The next group, somewhat iso- 
lated in position, and not closely 
related to the foregoing, is that of 
the ECHINODERMS, or Prickly Skins, 
including sea-urchins, starfishes, 
brittle -stars, sea -lilies, and sea- 
cucumbers; marine forms with limy 
skeleton and radiate symmetry, al- 
most always easy to recognise and 
classify. They have a peculiar 
" water vascular" system, which 
in the common starfish, for example, 
is connected with the delicate trans- 
_g parent tube-feet, by means of which 
the animal moves. 

The next great class is that of 
the ARTHROPODS, or animals whose 
bodies are made up of a series of 
rings or segments, which are fur- 
nished with hollow jointed feet. The 
vast majority of the shore Arthro- 
pods are CRUSTACEA, which take on 
the shore rocks the place taken by 
the Insects on land. The Crustacea 
include crabs, lobsters, shrimps, sand- 
hoppers, etc., animals with two pairs 
of feelers on the head instead of one 
FIG. 10 Fisherman's lob-worm pair as in Insects, with a har.l, limy 

Muft of bristles ;*; pa^aliV coat , and breathing by gills instead 

everted proboscis. A common of the air-tubes of Insects. Ihero 

are an enormous number of Crusta- 
cea on the shore, where they occupy all zones from high- 
tide mark to deep water. They are the great scavengers of 
the sea, for many of them live on dead and putrefying 
matter. In this respect also they resemble Insects, which 
are the great carrion feeders of the land. 



The last group of Invertebrate animals, or those without 
a backbone, is the MOLLUSOA, including Bivalves, like mussels, 
scallops, cockles, etc. ; 
Gasteropods, like peri- 
winkle and whelk; cut- 
tles, like squid and 
octopus. The Mollusca 
have soft, unsegmented 
bodies usually covered 
by a shell secreted by 
a fold of skin called 
the mantle, but many 
shore Molluscs have no 
shell. They usually 

breathe by gills Or by FIG. ll.-Common scallo 

the mantle, and have A bivalve Mollusc. 

a very characteristic 

muscular protrusion called the foot, which is usually the 

organ of locomotion, and is well seen in the garden snail, 

where it forms the creeping surface. 

The Vertebrates of the shore include the FISHES, easily 
recognised without special description, and the TUNICATES, or 
sea squirts, a strange set of animals much modified and not 
easy to recognise. Those on the shore are of two kinds 
the simple forms which are little shapeless sacs found under 
stones and overhanging rocks, and the compound forms 
which consist of little stars within a sheet of jelly-like 
substance which spreads over rocks and stones. The simple 
forms have two openings at the upper end, from which on 
an alarm they eject jets of water. They are enveloped in a 
usually tough tunic, which can be torn off, and reveals the 
soft body beneath. Of the details of structure something 
will be said later. 

The outline classification of shore animals just given may 
be summed up in the following table : 


Animals which at DO time of life have a backbone or any 
similar structure down the back. Gill-slits, or openings 
between the mouth-cavity and the exterior, present in fishes 


and sea-squirts, are here absent ; gills when present are out- 
growths of the skin. 

I. PROTOZOA Minute, usually microscopic forms, im- 
portant as furnishing food for higher forms. 

II. SPONGES. May be recognised by their spongy, 
porous bodies, furnished with one or more open- 
ings, and containing a skeleton of lime, flint, or 
horn. The crumb-of -bread sponge and the purse- 
sponge are common both in the fresh and dried 

III. CCELENTERA. Hollow-bodied animals, including sea- 

anemones, jelly-fish, sea-firs, " dead men's fingers," 
and many others. The mouth surrounded by 
tentacles bearing stinging-cells is a very character- 
istic structure. 

IV. UNSEGMENTED WORMS. The ribbon-worms have lank 

unsegmented bodies, very uniform throughout 
their length, and eject a thread or proboscis 
when alarmed. The Turbellaria are flat and leaf- 
like, and move with a peculiar gliding motion. 

divided into rings, or segments, which bear 
lateral tufts of bristles. Very many live in 
tubes, and then the bristles may be inconspicuous. 

VI. ECHINODERMS. Prickly-sldnned animals, usually with 
much lime in the skin; the body is more or less 
star-like, and the delicate, transparent tube-feet 
are very characteristic. Starfishes, brittle-stars, 
and sea-urchins are the commonest kinds. 

VII. ARTHROPODS. These, the animals with jointed legs, 
are represented by the hard -coated Crustacea 
shrimps, prawns, lobsters, crabs, sand-hoppers, etc. 
which are very varied in form, but are recognised 
by the segmented body, the jointed legs, the hard 
coat, the two pairs of feelers. 

VIII. MOLLUSCA. The Bivalves, such as mussels and 
oysters and so on, are readily recognised by tho 


double shell. The snail-like forms (Gasteropods) 
have sometimes a coiled shell, sometimes a conical 
one (limpet), and are sometimes without a shell. 
They can be generally recognised by the creeping 
foot and the horns on the head. The cuttles 
have many arms bearing suckers. All Molluscs 
have soft unsegmented bodies without appendages. 

Vertebrata are represented on the rocks by Tunicates or 
sea-squirts with their tough tunics, and by the Fishes, which 
can be recognised without difficulty. 

This account should enable even the beginner to fix 
roughly the position of the common animals of the shore, 
and is best learnt by repeatedly collecting all the animals 
found within a given area, say a large pool, and sorting them 
into their different categories. Such an operation can be 
readily performed on the shore, and will add greatly to the 
interest of the early visits to the rocks. It is easy to choose 
or make a series of little pools which may represent the 
different classes, then search the rocks in their neighbour- 
hood, returning after each excursion to the pools to place 
the spoils in their correct position. At first it is well to 
have an additional reservoir for. what the naturalist calls 
incertce sedis. It is not the least of the pleasures of field 
zoology to find how quickly the eye becomes trained, how 
the contents of the " uncertainty pool " steadily diminish as 
the perception of form increases, and the eye picks out 
perhaps the one obvious point which settles the position of 
the animal. Errors are of small moment, for after all there 
is error in the best and most recent classifications. Few 
years pass in which it is not shown to the scientific world 
that some form or other, not always an insignificant one, 
has been assigned to a wrong position, and the best arrange- 
ment is nothing more than an approximation. The point is 
to draw up a classification which will as far as may be 
express your knowledge. If it differs from that adopted by 
other people, this may be due to your ignorance or to theirs 
if you but go on you will soon find out which ; it is 
better to make an error and learn that you are wrong than 
to accept as dogma a classification which means nothing to 


When practice of this kind has rendered the commonest 
forms familiar, it is time enough to begin serious collecting. 
In the following chapters we shall consider the animals of 
the shore according to their systematic position, proceeding 
from the simpler forms to the more complex. This method 
has many advantages from the point of view of the ana- 
tomist, and is convenient for reference, but the novice when 
working with actual specimens will find detailed identifica- 
tions much more difficult in the case of simple forms like 
Sponges than in the more complex Crustacea, for example, 
which are comparatively easy to study. The shore crabs, 
indeed, make a good starting-point, for they are easily found, 
easily named, make in many cases most interesting and 
intelligent pets, and can be very readily studied. As, further, 
they all periodically cast their coats, and these coats which 
are an exact replica of the crab are always to be found on 
the beach, they are admirably suited to persons with humani- 
tarian tendencies. 

One other point deserves some notice. Very many people 
are afraid to handle almost any shore animal, because of a 
general conviction that all bite or sting. They may be 
reassured by learning that in our seas there are very few 
dangerous animals indeed. Apart from the true stinging- 
fish, or weever, there are one or two shallow-water fish, such 
as the sea-scorpions (Cottus), which are furnished with spines 
strong enough to wound an incautious hand. It is perhaps 
as well, therefore, not to handle living fish freely till you 
know something about them. Again, the very large jelly- 
fish which are sometimes to be found in the pools in autumn, 
especially those of the West Coast, can sting pretty severely, 
but with these exceptions almost any animal on the shore 
can be handled with impunity. It is of course obvious that 
the large Crustacea should be treated with discretion, for 
many of them can give a pretty sharp nip ; but the wide- 
spread fear of being "stung" is quite unjustifiable except 
in the case of the big jelly-fish and the weever. 

Finally, we may note that a tide-table is an important 
part of the equipment for serious work. This may be 
obtained either from a Nautical Almanack, or from most of 
the newspapers published in maritime towns. Collecting is 
most likely to be successful during spring tides, and should 


be begun from five to six hours after the time of full tide. 
In order to assist the beginner, a list of watering-places 
which have a reputation as offering good hunting-ground to 
the collector has been added to this chapter, but it should 
be understood that almost every maritime village offers 
facilities of some sort. The differences are chiefly differences 
of degree, and in many cases a place acquires a great 
reputation less on account of any outstanding merit than 
because of the patient research of some particular worker, 
who has given to the world long lists of animals as the 
results of his shore hunting. It may be well to emphasise 
the steady patience of such workers, lest the novice make 
a pilgrimage to one of the places mentioned, and le 
disappointed at not finding all the treasures for which the 
place is famous. It should be remembered that lists such 
as that of Professor Mclntosh for St. Andrews (see "Books 
of Reference" at end) represent years of hard work. We shall 
indicate subsequently the kinds of animals which may be 
expected to occur at different parts of the coast, but may 
note here that at such places as St. Andrews, North Berwick, 
Dunbar, Alnmouth, Whitley, and Scarborough, the shore 
fauna has a generally northern aspect. At the very many 
favourable spots on the coasts of Dorset, Devon, and 
Cornwall, such as Bournemouth, Poole, Weymouth, Port- 
land, Lyme Regis, Teignmouth, Torquay, Paignton, Falmouth, 
Penzance, and Ilfracombe, many rare and beautiful southern 
forms occur. These are also, though to a lesser extent, 
present at such places as Tenby, Aberystwyth, and around 
the shores of the Isle of Man ; while as we travel further 
north we find in the Firth of Clyde, e.g. at Millport, or on 
the West Coast, as at Oban, a certain admixture of northern 
and southern forms, the latter having spread up the warm 
West Coast. 


General characters of Sponges Some common Sponges Characters 
of the Coelentera How to keep them alive General account of 
Zoophytes and Sea-Firs The common Zoophytes and their 
swimming-bells The families of Sea-firs Some common Sea-firs 
Comparison between British Hydrozoa and those of other seas 
Characters of swimming-bells. 

OF the many-celled animals of the shore the Sponges are 
the simplest in structure, arid therefore should logically 
come at the beginning of an account of shore animals. 
They are, however, far from easy to recognise and classify, 
and in most cases the determination of species requires more 
skill and patience than can reasonably be supposed to be 
possessed by anyone but a specialist. A large part of the 
difficulty lies in the fact that sponges have no conspicuous 
external appendages, and no obvious organs which can be 
used in classification. The classification must therefore 
depend upon minute characters, especially upon the nature 
of the spicules points which are often difficult to study. 
We shall in consequence confine ourselves to such an 
account of British sponges as will enable the student to 
know a sponge when he sees it, and to be able to name 
one or two of the commonest forms. 

In the first place it should be understood that sponges 
are purely sedentary animals, so plant-like in appearance 
that they were long thought to be plants. As in so many 
sedentary shore animals, the young are minute and active. 
They settle down in sheltered places under overhanging rocks, 
on stones, on the broad fronds of weeds, and not infrequently 
on living animals, especially Crustacea. From the places 



where they once attach themselves the sponges never move. 
They feed on minute particles contained in the water, which 
is swept through the porous body in continuous streams. 
Most of them bud freely, often forming large colonies which 
spread over the rocks as lichens spread over trees. With 
very few exceptions, they all contain a skeleton in the form 
of fibres or sharp spicules. The colours are often variable 
and bright, and as a little shore hunting will soon convince 
you, sponges often have an unpleasant smell ; in this respect 
they resemble the more beautiful sea-anemones, which often 
give a peculiar and disagreeable odour to the dark caverns 
in which some species love to dwell. Sponges can generally 
be recognised by the presence of distinct pores, and the 
characteristic "spongy" appearance of the substance when 
torn. In some cases not a little care is required to distin- 
guish them from certain compound sea-squirts, which may 
contain spicules, and from Polyzoa, or sea-mats, which often 
contain a large amount of lime, and are occasionally not 
unlike sponges. Both sea-squirts and Polyzoa, when care- 
fully examined, show the presence of "polypes," of which 
there is, of course, no trace in sponges. 

Without making any attempt to discuss the classification 
of sponges, we may briefly note the salient characteristics 
of three common forms. 

By far the commonest sponge on the shore rocks is the 
crumb-of -bread sponge (Halichondria panicea), which forms 
a thick crust, often many inches square, over rocks and 
stones in all sorts of situations. It seems to grow equally 
well when fully exposed to light and when sheltered in dark 
crevices, and though perhaps commonest on a flat surface 
does also occur on various seaweeds, especially the stems of 
Laminaria, or oar- weed, which are often completely invested 
by the sponge. There are indeed few spots on the tidal 
rocks where the crumb -of -bread sponge cannot obtain a 
foothold. In the dry state it is commonly found on the 
shore, and such dried specimens sometimes puzzle the 
beginner by appearing much more " spongy " than the living 
sponge as found on the rocks. This is due to the partial 
loss of the soft parts which brings the skeleton into greater 
prominence. In colour the sponge varies greatly; it is 
often distinctly green, and at other times shows various 


shades of yellow, brown, and drab. Dried specimens found 
on the beach are always colourless. In the living sponge 
the most conspicuous feature is usually the number of 
openings or oscula, which stud the surface and are raised 
on little prominences, but in specimens which have grown 
in a spot where space is limited, as on one of the smaller 
seaweeds, these oscula are less conspicuous. The surface of 
the sponge is marked by a distinct network of lines, and 
when its substance is torn with needles it will be found that 
it is full of minute flinty spicules. 

Another very common sponge is Graniia compressa, the 
purse-sponge already mentioned. It is dull in tint, being 
greyish brown in colour, and rarely grows -in such exposed 
situations as the crumb -of -bread sponge. It is usually to 
be found under overhanging rocks with the orifice hanging 
downwards, and the base attached to the rock surface. It 
is sac-like in shape, and in the dead state much flattened 
and compressed. In life, however, the central cavity is full 
of water, and the sponge is much plumper in appearance. 
It is of much interest, because it was in it that Robert 
Grant after whom it is called first discovered that in 
a sponge currents of water enter the central cavity by 
minute pores, and leave it by the large osculum. These 
currents can be readily observed in living specimens placed 
in sea-water containing solid particles in suspension. The 
sponge differs from Halichondria in having a skeleton made 
of spicules of lime and not of flint, and in being usually 
simple, whereas Halichondria, with its many oscula, is an 
example of a compound sponge. Occasionally budding 
occurs, so that there may be as many as seven or eight 
oscula, but the usual form is that of a slightly stalked sac 
with one terminal opening. The skeleton, made of three- 
rayed spicules, may be seen by teasing a little of the sponge 
substance under a lens, and the fact that it is limy may be 
proved by adding a drop of dilute acid, when effervescence 
occurs as in the case of limestone under the same circum- 
stances. The minute pores in the walls of the body are not 
easily seen except in dried specimens, and even then they 
are largely concealed by the spicules. The purse-sponge is 
very common between tide-marks, but is usually only about 
/in inch long, and is somewhat inconspicuous. 


A smaller but much more dainty little sponge is Grantia 
ciliata, a delicate silky little creature not usually more than 
half an inch in length. It is oval in form, of a cream or 
greyish colour, and has a crown of beautiful spicules round 
the osculum. It is a solitary form and usually occurs far 
out on the rocks. When examined with a lens it will be 
seen that the silky appearance is due to the fact that the 
surface is covered with prominences, each ending in a long 
slender spicule. In life the direction of the crown of 
spicules varies according to the flow of water through the 
sponge; sometimes they spread outwards in a radiating 
manner, and at other times they lie parallel to the long 
axis of the sponge. This pretty little sponge is not very 
common on the shore, and usually requires to be sought for. 

These three examples may serve to give the student some 
idea of sponge structure ; on certain parts of the coast, 
especially on the South, other species are common between 
tide-marks, but for these reference must be made to special 

After the sponges we come to the hollow-bodied animals, 
or Coelentera, which include some of the most beautiful of 
our shore animals. Lovely as they are in life, both in 
colour and form, they lose practically all their beauty at 
death, when the majority become mere shapeless masses. 
In consequence they must be studied in the living con- 
dition, and this is fortunately rendered possible by the fact 
that not a few will live well in confinement. This is, of 
course, especially true of the sea-anemones, which make 
charming pets. A few words may be said as to the best 
methods of keeping the more delicate sea animals alive. 
Those who have abundance of spare time, much patience, 
and not a little spare cash will probably take naturally to 
aquarium-keeping that is, to the maintenance of tanks con- 
taining sufficient growing plants to balance the animal life. 
Even when all these requisites are present, however, the 
aquarium is always liable to go wrong, and is never very 
easy of management except on a very small scale. By far 
the easiest method of keeping marine animals alive is in 
flat shallow pans, which expose a large surface to the air 
relative to the bulk of water present. A common pie-dish 
of large size does well. It should only be about half full, 


and at most should contain only two or three small animals. 
If it is kept carefully cleaned, and has fresh water added to 
make up for loss by evaporation, it will be found unneces- 
sary to change the water for a very long period. In such 
a dish many of the shore animals will live well, and there 
is much more chance that you will really observe the habits 
of your pets if each one has a dish to itself than if they 
are placed in a crowded aquarium among many other 
animals. The points of special importance are : do not 
crowd, and do not use a vessel which holds a great bulk 
of water proportionate to the surface exposed to the action 
of the atmosphere. Some shore animals, such as the com- 
mon crab, the common limpet, and others, will only live 
where they are partially exposed to air, and a great number 
are much more sensitive to impurities in the water than to 
a partial exposure of their surface to the atmosphere. 
Finally, in keeping marine animals in confinement, do not 
forget that the object, as well as the justification of the 
practice, is that you may observe their habits ; therefore do 
not forget to look at them, to notice their changes, to draw 
them if possible. 

The Coelentera, or sea-nettles, as the German popular 
name may be translated, form a very large group, including 
a number of different kinds of animals. The most obvious 
common character is the presence of tentacles, which bear 
the stinging-cells to which the German name refers. Let 
not the name alarm the sensitive naturalist, however, for, as 
already mentioned, in this country, except in the case of 
the jelly-fish and such southern forms as the " Portuguese 
man-of-war," these stinging-cells will not penetrate our skin. 
We may begin our study of the group by examining a very 
delicate and harmless little creature, one of the zoophytes or 
animals like plants. If you examine the shore pools with a 
little care, you will find a number of spiral shells lying 
apparently loose at the bottom, with their surface often 
covered with a brown or pinkish crust. As you watch, the 
apparently empty shells will move away with considerable 
speed, disclosing the long legs of a hermit-crab as they do 
so (see Fig. 3). Pick out the shell in which the surface 
crust seems to be best marked, and drop it into a shallow 
dish filled with sea-water. In a few minutes the hermit 



will recover his equilibrium, and once more appear on his 
doorstep. About the same time the dingy crust on the shell 
will change its appearance, and show you a delicate waving 
forest of little pink creatures, which spread out in the water 

Fia. 12. -Diagram reprcs. nting the individual persons or - 
zooids in a colony of Hydractinia echinata. a, nutritive 
person with tentacles extended ; b, sensitive person with 
ab< rted tentacles ; c, reproductive persons bearing clusters 
of sporosacs. At the bases of the persons are shown the 
stout protective spines. After Allman. 

like miniature flowers. The whole crust constitutes a zoophyte 
colony, the tiny flowers are the members of the colony, and 
are called polypes, or better, zooids. We have begun our 
study of the sea-nettles with a colony of this kind, rather 
than with the more familiar sea-anemones, because the 


members of the colony show the characteristic sea-nettle 
shape in perhaps its simplest form. Each zooid, as the 
figure shows, is like a tiny hollow column; it is fixed by 
one end to the shell, while the other end, with its crown of 
tentacles, floats freely in the water. Small as the tentacles 
are, they still bear stinging-cells, which paralyse the prey 
caught by the tentacles. 

With the help of a lens and patience we can carry our 
observations considerably beyond this point, and make out 
that though the little zooids are similar in their broad 
outlines of structure, there are marked differences in detail. 
In the majority of the individuals (see diagram) the body 
is long and cylindrical, ending in a mouth surrounded by 
twenty to thirty tentacles. These are the "nutritive persons" 
of the colony, which catch and digest the little particles 
which constitute the food of the entire colony. Their 
central cavities are connected with a series of canals which 
ramify over the surface of the shell on which the colony is 
placed, and are again connected with the central cavities of 
the other zooids. By this means the food is conveyed in a 
digested condition all over the colony. The other zooids 
are of two kinds. Near the margin of the colony, and 
overhanging the mouth of the shell, there are peculiar 
long spiral individuals (marked b in diagram), which are 
extraordinarily muscular and active, but are without mouth 
and tentacles. The function of these "sensitive persons" 
seems to be to warn the other members of the colony of the 
approach of danger.' Scattered among the nutritive persons 
are the third set of zooids (marked c in diagram), which are 
similar to these, but only about half as high, and have 
rudimentary mouth and tentacles. The special peculiarity 
of these zooids is that they bear lateral clusters of sporosacs, 
which are oval bodies containing eggs or male elements. 
In Hydradinia echinata, as the zoophyte is called, the 
sporosacs remain permanently attached to the colony, but in 
very many of the zoophytes minute swimming-bells, or 
medusoids, are produced instead of sporosacs, and these 
swimming-bells float away, and carry the eggs to some more 
or less distant spot. Finally, in Hydradinia there are 
mingled with the persons a number of spines, which may 
be aborted persons, and which have some protective function. 


From this description of Hydradinia a general idea of 
the character of the Coelentera may be gathered. The 
members of the group are usually either polypes, like those 
of Hydradinia, or are jelly-fish, like the swimming-bells of 
many zoophyte colonies ; but both types of structure occur 
in many much-modified forms. Both types not infrequently 
occur in the course of one life-history, and then the phe- 
nomenon which we have already studied as alternation of 
generations is produced. Many forms are colonial, like 
Hydradinia, and in such colonies there may be division of 
labour among the members of the colony. 

The Coelentera are very numerous, and are found in all 
seas and at all depths ; but the different parts of the ocean 
have their characteristic forms. Thus, as we all know, the 
reef-building corals are confined to the warm seas, and even 
in the British area there are far more sea-anemones on the 
South and West than in the colder waters of the East 
Coast, while certain zoophytes which occur in the North and 
East are absent in the South and West. 

In studying the Coelentera we shall begin with the zoo- 
phyte colonies, similar to Hydradinia, which are so abund- 
ant on our coast. Of these, Hydradinia is, in one sense, 
a relatively simple type, for its skeleton is only represented 
by the crust which covers the shell on which the colony is 
placed, and by the little spines arising from this crust. In 
most of the zoophytes the colony is surrounded by a pro- 
tective sheath, which sometimes forms little cups in which 
the individual zooids are placed. As the sheath is tough 
and resistant, it not only keeps the colony expanded during 
life, but also persists after the death of the zooids. These 
dead colonies are often flung up on the beach, and are more 
familiar to most people than the living zoophytes. From 
their peculiar method of branching they are known as " sea- 
firs," or are often incorrectly regarded as " seaweed." The 
first class of Coelentera, therefore, includes delicate zoo- 
phytes, with practically no skeleton, such as Hydradinia 
and many others ; the sea-firs, with their resistant coat ; 
the swimming-bells, or medusoids, which arise from many 
zoophytes and sea-firs; and also some other colonial forms 
much less common in our seas. This first class is termed 
the HYDROZOA, and the individual zooids, or polypes, are 


called hydroid, from their general resemblance to the little 
fresh-water Hydra. 

Among the zoophytes and sea-firs the character which 
varies most, and which affords a basis for classification, is 
the skeleton. Let us first understand what this skeleton 
is, and what is its function. Both the terms "skeleton" 
and " supporting substance," which one naturally applies to 
it, are misleading, because both suggest the idea of support. 
Now the sea-nettles do not require support for their soft 
parts, because these can be, as it were, stretched by the 
water which the animals take into their central cavity. 
An anemone when extended, i.e. when filled with sea-water, 
is firm and tense ; it is only when it ejects this water that 
it collapses. The main object of the skeleton in those sea- 
nettles which possess this structure must therefore be to 
serve as a means of protection. Take our little pink 
Hydradinia, for example. When alarmed the zooids con- 
tract and cower down among the spines, so that an in- 
quisitive foe darting at the floating pink things will find 
them lost among these hard inedible thorns. Again, look 
at any of the common sea-firs so frequent on weed. The 
tiny branches are crowded with zooids, possibly edible 
enough, but each of these is placed in a little cup of horny 
matter. When alarmed they withdraw into the cups, 
and a persevering enemy is likely to get a maximum of 
indigestible horn, and a minimum of digestible zooid. 
Zoophytes and sea-firs are extraordinarily numerous on the 
shore rocks, and in most cases they are protected to a 
greater or less extent by a horny skeleton. " , 

In the minority the skeleton is represented either by a 
mere plate at the base of the colony, or by tubes which 
envelop some part of the columnar body. In these naked 
forms (Gymnoblastea) the individuals are often large and 
highly coloured with numerous conspicuous tentacles. In 
the majority of the shore forms the skeleton is greatly de- 
veloped, and carries little cups, in which the zooids are 
placed, and into which they can be completely retracted. In 
this set, called Calyptoblastea from the cups, the individuals 
are small, but usually very numerous, and the skeleton is the 
most conspicuous part of the colony. 

We shall mention the salient characteristics of a few of 


the commonest naked zoophytes ; for such detailed descrip- 
tion as may render the recognition of actual specimens 
possible, reference should be made to the tables at the 
end of the chapter. 

In Hydractinia we have already described a zoophyte in 
which the skeleton is very slightly developed, but there is 
another pretty form in which there is even less horny 
matter. This is the club-shaped zoophyte ( Clava squamata), 
often exceedingly common between tide-marks. If in shore 
collecting you are endeavouring to throw back the heavy 
dripping curtains of bladder- wrack, which hang pendent in 
front of the great rock-clefts, you may often notice little 
pink fleshy spots on the weed. In- 
significant enough they look, but it 
is well worth your while to break off 
a bit of the weed and drop it in a 
clear pool. You will then find that 
the fleshy mass is a dense cluster of 
short stout zooids, which soon un- 
fold in water and display their 
characteristic club-shape (see Fig. 
13). Each bears numerous scattered 
thread-like tentacles, and at times, 
in addition to these tentacles, one 
finds that the zooids have a distinct FIG. is. ciava squamata on 
collar made up of little beads. These weed - After oilman, 
are clearly shown in the figure. Each bead is a sporosac, 
containing eggs, which grow directly into fresh colonies. 
The individuals may reach a length of about an inch, but 
the colonies never contain very many individuals. There is 
no skeleton save a slight attaching plate on the weed. 

As the next stage in the development of skeleton we 
may mention Hydractinia where we have the spines in 
addition to the basal plate. It is also remarkable because 
of the fact that, as already mentioned, the colony includes 
three different kinds of individuals. This " polymorphism," 
or occurrence of more than one form, is rare among the 
Hydrozoa of the shore, though it commonly occurs among 
those of the open sea, e.g. in the "Portuguese man-of-war" 
of the South Coast. 

In the next zoophyte to be mentioned we find that the 



skeleton forms tubes in which the zooids are placed, much 
as a worm lies in its tube. In examining the more delicate 
kinds of weeds on the shore, a quick eye will often pick 
out small yellowish tubes branching among the weed, and 
bearing small zooids with numerous scattered tentacles, 
remarkable in having a prominent knob at their tip, 
whence they are called capi- 
tate. These zoophytes are 
species of Coryne and Syn- 
coryne. Without going into 
the characters in detail here, 
let us notice one interesting 
point in regard to. the repro- 
duction. In all the zoophytes 
described as yet we have 
noticed the occurrence of 
little sporosacs, structures 
which lie like little fruits 
on the wall of the body, 
and bear the eggs from 
which new colonies arise. 
These are present again in 
Coryne, clustering at the 
bases of the tentacles, but 

in Syncoryne, although the same little fruits are to be seen, 
they do not set free eggs, but tiny bells of jelly, which 
swim away through the water with a gentle pulsating 
movement. After being set free the bells undergo various 
changes, and become converted into swimming-bells, or 
medusoids, called Sarsia (Figs. 6 and 15), often found near 
the surface of the sea in autumn. They, together with 
many other medusoids, may be caught by sweeping the 
surface of the rock pools or the open bay with a fine net 
on a calm day. Any medusoid resembles more or less 
exactly a bell in shape, With a stalk or manubrium hanging 
down in the centre to represent the clapper. We must, 
however, suppose the upper part of the bell to be much 
thickened, for it consists of a mass of transparent jelly, 
which fills up, as it were, the upper part of the hollow of 
the bell. Further, the mouth of the bell is largely filled 
up by a transparent shelf which projects inwards from the 

FIG. 14. Syncoryne eximia. 
After Alhnan. 


margin, leaving only a central hole. This shelf is called 
the veil, or velum. From the margin of the bell, or 
umbrella as it is often called, long tentacles project, the 
number varying in different forms. At the base of the 
tentacles, or between them, are placed small sense organs, 
often of much importance in classification. The mouth of 
the medusoid is placed at the end of the clapper, and opens 
into a cavity, which communicates with fine canals radiating 
through the jelly of the bell. All these characters can, in 
the case of some of the larger swimming-bells, be readily 
made out, especially in living specimens, and on a calm 
summer's day no difficulty should be experienced in obtain- 
ing living medusoids. Even if a net be not at hand, it is 
often possible to catch the little creatures from a boat in a 
small bottle ; and there is, perhaps, no better way of study- 
ing them than under such conditions, with the sunlight 
playing on the water and the boat gently rocking beneath 
the naturalist's feet. Then the delicate pulsating bells take 
on a new beauty, and every movement displays some fresh 
charm to delight the eye. It sometimes happens, on an 
exceptionally calm day, that the surface 
water simply swarms with medusoids of 
many shapes and tints, varying in size from 
tiny creatures, just discernible, as they float 
along, to those with a diameter of about half 
an inch. The size should be compared with 
that of the large jelly-fish, which are not 
very nearly related to the medusoids. 

As to the special characters of Sarsia, we 
may notice that in the mature stage the manu- 
brium, or clapper of the bell, is very long 
and thick, extending downwards considerably 
below the margin of the umbrella. This 
character enables one to pick out the tongued 
Sarsia, as it is often called, very easily from 
other swimming-bells. It, together with the 
other structural points described, can be 
clearly made out from the figures. In this FlQ 15 _ Sargi t 
tongue, or clapper, the eggs are developed, so swimming - beii, 
that while in Conjne the eggs must fall near JK * 
the parent colony, in Syncoryne, by the mucks. 


intervention of the swimming-bell, they are carried away 
some distance from the parent colony. The swimming-bell 
seems to exist only that it may perform this function of 
carrying away the eggs, and in structure it is, as it were, a 
zooid which has become adapted for a free-swimming life in 
the open water. Like the zooid it has tentacles, but these 
are few in number (only four), and relatively very long. 
They hang down from the margin of the bell, and are 
abundantly supplied with stinging threads. It should be 
noticed that though Sarsia seems large in comparison with 
the size of the zooids of Syncoryne it may have a diameter 
of three-quarters of an inch yet its bulk is largely due to 
the contained jelly, which is again largely water. 

The last member of the Gymnoblastea which \ve shall 
consider is the large and beautiful Tubularia indivisa, which 
again produces sporosacs and not swimming-bells. It is a 
form in which the stems are sometimes as much as a foot 
long, and which is especially common on piers and landing 
stages. It also occurs on rock surfaces and stones on the 
shore, but usually near low-water mark. If, as sometimes 
happens, you know that it is growing in abundance on some 
rocky ledge or pier support not readily accessible with the 
resources at hand, an indirect method of obtaining speci- 
mens may be tried. That is, you may anchor by means of a 
stone a log of wood in the vicinity of the spot, and you will 
probably find that in a few weeks the log will become 
covered with a luxuriant growth of zoophytes, including the 
desired Tubularia. I have seen singularly beautiful speci- 
mens obtained in this way. The prudent naturalist will, of 
course, also not neglect such possible sources of supply as 
buoys, which are often taken up regularly to be cleaned, old 
boats left anchored in quiet coves, and wreckage. 

One of the special peculiarities of Tubularia, by which it 
is distinguished from any other zoophyte we have described, 
is the arrangement of the tentacles. These are arranged in 
two circles, of which the one (a in Fig. 16) surrounds the 
mouth and consists of very short tentacles, while the other 
(b in Fig. 16), whose members are long, is placed at a 
considerable distance below the mouth. Between the two 
circles are placed the sporosacs (c in Fig. 16), which in 
T. indivisa are borne on branched stalks, and hang down 



on all sides like little bunches of grapes. The colony is 
invested with a straw-coloured skeleton, and as the stems 
are unbranched, each resembles an "oaten pipe." The stems 
are not ringed, and 
narrow towards the 
base, where they are 
twisted and inter- 
laced. The zooids are 
bright pink, and pro- 
ject like beautiful 
flowers from their 
straw-like tubes. 
Besides T. indivisa 
with its unbranched 
tubes there are 
several other species 
of Tubularia, but 
these come from 
deeper water or are 
less common. The 
large size of the 
zoophytes and the 
beauty of their 
colouring make T. 
indivisa one of the 
most beautiful of our 
Hydrozoa. Each 
sporosac contains 
only a single egg, 
which undergoes the 
early stages of its de- 
velopment within the 
sac. The embryo, 
when set free, has 
some slight power of FlG 
independent loco- 
motion, and must also be readily carried about by currents. 
We come next to the true sea-firs (Calyptoblastea), in 
which the skeleton reaches a much higher degree of de- 
velopment, and which are, above all, remarkable for their 
delicate tracery. Many of them, as they spread out in the 

W. Colony of Tubularia inoivisa, showing 
the zooids in their tubes. After Allman. 


water, show a beauty of form which rivals that of the 
loveliest of ferns, while others display the coarser fir-like 
appearance which has given them their common name. 
The individual zooids are usually much smaller than in the 
Gymnoblastea, and this fact, together with the greater de- 
velopment of protective substance, gives them less beauty 
of colour. One rarely finds among them those lovely rose 
tints which make the colonies of Clava, Coryne, and 
Tubularia so delightful to the eye. Though the individual 
zooids are small, however, the colonies often reach a large 
size, so that the number of individuals is enormous. The 
species are difficult to identify, and the beginner must often 
rest content with the genus, or even with the family. In 
many cases the determination of the species requires the 
aid of the microscope. On account of the number of 
common forms, we shall alter slightly our usual method 
of procedure, and study chiefly the characters of the 

A great number of the littoral forms are Campanularians 
(fam. Campanularidse), and are distinguished by their bell- 
shaped cups borne on the end of short stalks. The shape 
and situation of these cups give the members of the family 
a certain delicacy of 'form, which makes them readily 
recognisable. The zooids are remarkable in possessing a 
large trumpet-shaped proboscis, and generally reach a con- 
siderable size. Some of the Campanularians give rise to 
medusoids, others have sessile sporosacs. In both cases the 
colony produces specially modified cups (gonothecse) ; but 
while in the one case the cups contain sporosacs within 
which the eggs ripen, in the other they open early and 
allow the tiny medusoids to float away, carrying the eggs 
with them. As each gonotheca may contain many medu- 
soids, and the colony bears innumerable gonotheca}, it is 
easy to understand how the countless medusoids found at 
the surface of the sea in autumn originate. While it is 
easy to recognise a Campanularian, it is often difficult to 
determine the species, or indeed in some cases even the 
genus. In most cases the number of teeth on the margin 
of the cup, and the number of rings on the stems, constitute 
important points. 

Of the many Campanularians on the shore, three species 


may be briefly described, as they are so common that almost 
every patch of rocks will furnish examples. If at an ex- 
ceptionally low tide you make your 
way right out to the margin of the 
rocks, where the great oar -weed 
spreads its long fronds, or if a calm 
summer day permits the slightly 
dangerous experiment of a boat 
among the rocks, you will notice that 
the oar-weed is often covered by a 
miniature forest of sea-firs. Especi- FIG. w.OMia genicuiata on 

.,, ,. , . , r weed. After Hmcks. 

ally will you notice one which con- 
sists of slender zigzag stems, giving off stalked cups bear- 
ing tiny crystalline specks the expanded zooids. This is 
Obelia genicuiata^ seen at its best only thus in the Lami- 
narian zone, but in the dead state common enough at all 
seasons on the torn-off weed of the beach. It gives 
rise in the summer months to countless myriads of 
tiny swimming - bells, which are liberated from little 
cases, or gonothecse, borne on the stems. If myriads seem 
to you an exaggeration, take a few patches of the sea-fir 
and make a rough computation even of the gonothecse pro- 
duced by a patch of ordinary size: If your patience does 
not speedily give out, you may acquire some perception of 
the prodigal profusion of nature on the seashore, and of 
the intensity of the "struggle for existence" which must 
go on there, where so many species produce eggs numbered 
in millions. 

Another common Campanularian Clytiajohnstoni is to 
be found on almost every object within the shore area 
which offers a foothold shells, weeds, stones, rock surfaces, 
are eagerly taken possession of, but the back of a spider-crab 
is also a dearly prized position. Almost any spider-crab 
taken at random will show you the simple unbranched 
stalks of Clytia, each ending in a solitary bell, but you 
should also look for it on rock surfaces, as a good means of 
training the eye. It is by no means a conspicuous object. 

Let us mention one other common Campanularian which 
is also to be found everywhere between tide-marks. This is 
Campanularia flexuosa, which often grows, intermixed 
with weed, in patches of great extent, and can be recognised 



by the large cups 
and characteristic 
" flexuous" branch- 
ing. The figure 
shows its general 
characters very 
clearly. Together 
with the two pre- 
ceding species it 
serves to indicate 
the characters of 
the family, and 
being not incon- 
spicuous, is of 
some importance 
in giving rock 
pools their char- 
acteristic appear- 
ance. Though the 
sea-firs must, on 
account of their 
horny skeleton, be 
somewhat indi- 
gestible, yet they 
are eaten by at 
least the sea-slugs. 
They also serve 
as shelters for 
hosts of the more 
delicate animals, 
many of whom 
pass their lives 
clinging to their 
branches. The 
forests of Cam- 
panularians are 
therefore worth 
a little study, 

Fio. 18. Magnified representation of a branch of even if Only for 

Campanularia flexuosa. a. empty cup ; b, cup with J.T r p Q<3mi 

expanded zooid; c, gonotheca. Note the ringed tm L<-SUII. 
"flexuous" stem. After Hincks. Though to the 


beginner it may seem that the sea-firs are less interesting 
than some of the more "lively" of the shore animals, 
we shall rapidly review all the more important families, 
partly because they afford most interesting examples of 
progressive evolution, and partly because the study of 
them constitutes an admirable training in minute accuracy 
of observation. A wet evening spent over a handful of 
sea-firs, studied with the aid of the low powers of the 
microscope or a good lens, will be found of great value 
to anyone at all interested in species work. 

A very insignificant little sea-fir Opercularella lacerata 
may serve to indicate the characters of the family Campa- 
nulinidse, which represents the process of transition from 
the Campanularian condition to that found in other families. 
This sea-fir has stalked cups, but they are not bell-shaped, 
but ovate and conical, while the zooids are cylindrical with 
a short proboscis. A special peculiarity is that the cups can 
be closed by an elaborate lid, or operculum. 

The next stage in the transition from the Campanularian 
condition is seen in the family Lafoeidae, where the cups are 
tubular and almost without a stalk (sessile). The only 
example we shall consider is Lafoea dumosa, which occurs 
both on the shore and in deep water. It may reach a 
height of four inches, and is then erect and irregularly 
branched, but the specimens found between tide-marks are 
usually small and have simple creeping stems. The tubular 
cups are very numerous and spring from all sides of the 
stem. The whole colony has a yellowish tint. 

One other small transitional family must be mentioned, 
which includes the curious "herring-bone coral," a species 
often cast up on the beach, and occasionally found between 
tide-marks. The whole colony is figured on page 319. It 
is a large form, sometimes reaching a height of ten inches, 
and is peculiarly stiff and rigid, differing in this respect 
from the majority of the plant-like sea-firs. The Latin 
name of this form is Halecium halecinum, and it belongs to 
the family Haleciidse. The special peculiarity is that the 
cups are sessile, and are placed in two rows on the stem (see 
Fig. 19). This recalls the conditions seen in the next 
family, the Sertularians ; but there the cups are let into 
the stem, while those of Halecium are placed on a project- 


ing process, and are tubular or almost campanulate. The 
stem is much branched, after the fashion called pinnate, 

and the cups are alternate. 

The next family is that of 
the Sertularians (Sertularidae), 
which includes a large number 
of forms, usually easy to 
recognise, and represented 
both in the living condition 
on the rocks, and among the 
dried wreckage of the shore. 
The cups are entirely sessile 
and are sunk in the stem, the 
result being to give the stem 
and its branches a character- 
istically stout appearance as 
compared with the filmy 
threads of many of the Cam- 
panularians. The cups usually 
occur on both sides of the 
stem, and the zooids are com- 
pletely retractile, so that after 
death they are rarely visible. 

The first genus of this 
family is Sertularella, which 
contains one or two not uncommon littoral forms. We 
shall describe only one species, chosen because it is not only 
widely distributed round our own coasts, but also occurs in 
most seas. This is S. polyzonias, a pretty straw-coloured 
zoophyte, which often reaches a considerable size. Like all 
the members of its genus, it has its little cups placed al- 
ternately, and this, together with their shape, gives a 
peculiar and characteristic appearance to the whole colony. 
Each cup has a toothed margin, and can be closed by an 
operculum made of several pieces. The different species of 
the genus are distinguished especially by the shape of the 
cups. In S. polyzonias these are urn-shaped, and bulging 
below with a divergent four-toothed aperture. In fact, they 
somewhat resemble the calyx of the Figwort. The stems 
are slender and much, but irregularly, branched. 

From the species of Sertularella it is usually easy to 

FIG. 19. Magnified fragment of a 
branch of Halecium, showing the 
peculiar tubular cups ami the ex- 
panded zooids. After Hincks. 


distinguish at a glance the species of Sertularia, which have 
usually opposite cups, and stems which appear to be made 
up of a succession of triangular joints, the base of the 
triangle being directed upwards. By far the commonest 
species is S. pumila, an insignificant little zoophyte, which, 
with its loosely branching stems, often occurs in great pro- 
fusion on the shore rocks. It has a special preference for 
the blades of the larger weeds, and is readily recognised by 
the regular V-shape of the joints of which the stem is 
composed. The cups in which the zooids are placed form 

FIG. 20. Sertularia pumila, and a magnified representa- 
tion of a portion of a branch, a, gonotheca ; &, empty 
zooid-cup. After Hincks. 

the upper part of the diverging arms of the V (see Fig. 20). 
We may repeat here that to recognise the species of sea-firs 
requires a little skill and the use of the microscope. The ex- 
amples which have been briefly described are intended to 
give the student some notion of the modifications of structure 
seen in the chief families, and assist in the recognition of at 
least the family of the common forms. More than this will 
probably be found difficult for the beginner. Several species 
of Sertularia are fairly common between tide-marks, and 
others are frequently thrown up on the beach, and are to 
be found attached to other animals so thrown up. To settle 
the species of these is often difficult, but it is much to learn 
that they are Sertularians, and to realise their differences 
from the other hydroids often so plentiful in the same place. 
Before we leave the family two other forms may be 
briefly mentioned, which differ very much in appearance 



from other Sertularians. Both do occur occasionally in the 
Laminarian zone, but are most commonly found among the 
shore wreckage. There their peculiar shapes have made them 
both noticeable objects, and have given to the one the name 
of " sickle-coralline " and to the other that of " bottle- 
brush." So remarkable is the resemblance of the latter to 
the object indicated in its common name, that people fre- 
quently refuse to regard it as an animal production at all. 

First as to the "sickle-coralline" (Hydrallmania falcata). 
It is a large form, reaching a height of a foot or more. Its 
general appearance may be described in the 
words of Sir John Dalyell as "a series of 
feathers implanted in spiral arrangement round 
a slender stem," but when dried the "feathers," 
or "plumose branches," become curved or sickle- 
like. The zooid-cups are placed on one side of 
the pinnas only, a fact which makes the whole 
zoophyte resemble the next family the Plumu- 
Iarida3 rather than the other Sertularians. 
Further, they are placed in clusters on each 
joint of the stems, and are tubular in shape. 
The "sickle -coralline" is a zoophyte which is 
very likely to be mistaken for "seaweed." 

The "bottle-brush" (Thuiaria timid] cannot 
be honestly described as anything but ugly. It 
consists of a long naked stem with a small 
"brush" at the top, and is of a dull brown 
colour. It may attain a height of twelve 
inches, but specimens of six to seven inches 
are more common. The brush varies in size, 
but not infrequently occupies about one-third 
of the stem. As the stem grows and branches at 
the top, the lower branches fall off, so that the 
brush does not necessarily increase in size with 
the growth of the colony. In consequence, further, 
of this method of growth, the naked portion of 
the stem shows throughout the scars where the 
old branches have fallen off. The botanist will 
rTifiaria a ^ once perceive the resemblance in method of 
thuia. After growth to a tree-fern, or to many palms. The 
cups containing the zooids are so sunk into the 



substance of the branches as to be discernible only with 
difficulty. They are arranged in two rows. 

The last family of the Calyptoblastea is the Plumularidae, 
including some of the most delicately beautiful of the 
zoophytes. Most are beautifully and elaborately branched, 
so as to produce "plumes" rivalling those of the most 
delicate ferns (see Fig. 9, p. 29). In all the cups are 
sunk into the branches, and are placed on one side of the 
branches only. As they are usually small, one result of 
this arrangement is to make them very inconspicuous, so 
that to the unaided eye there is nothing to destroy the 
plant-illusion. The gonothecae always contain fixed sporo- 
sacs. A final peculiar character is that the colony bears, 
in addition to its zooid-cups, much smaller cups, called 
nematophores, which contain stinging- cells. These are 
usually very minute, and require the aid of the micro- 
scope before they can be seen. Of the Plumularians 
we shall describe one example only, the delicate little 
Plumularia setacea, which is quite common on the shore 
rocks. Its graceful plumes reach a height of over an inch, 
which is not small for a littoral zoophyte, but their texture 
is so delicate and fragile 
that they are not easily 
seen. Each tiny plume 
rises independently from 
the creeping stolon, and 
is so transparent that, 
except when the white 
reproductive capsules are 
present, it requires a 
quick eye to discern it. 
The special peculiarities 
of the species lie in the 
minute structure of the 
pinnas, or branches. 
Examined with the 
microscope these will be 
found to consist of joints 
which are alternately 
long (d) and short (e), 
and of which the longer 

FIG. 22. Magnified branch of Plumularia. 
The letters are explained in the text. 


only bear zooid-cups (a), a single one to each. Above each 
cup are two minute cup-shaped nematopliores (/), while 
beneath each is a single one (b"). The short joints also bear 
a single nematophore, but no zooid-cup. Other nematophores 
occur at the joint of origin of the pinna3, and on the main 
stem (b" r ). The gonothecaB (c) arise at the angle between 
pinnaB and stem, and are remarkable for their long tubular 

The Calyptoblastea are so abundant on the shore that 
even at the risk of wearying the reader, we may briefly 
review the different families. Sea-firs which bear distinct 
bells borne on stalks belong to the Campanularians, which 
have large zooids, and vary much in their branching. 
Where stalked cups occur which are not bell-shaped, but 
ovate and conical, the colony must be referred to the 
Campanulinidse ; but if the cups are numerous, tubular, 
and without a stalk, then the specimens belong to the 
LafoeidaB. In the " herring-bone coral " the cups are similar 
and also without a stalk, but they are arranged in two rows 
at the sides of the flattened stem. In the Sertularians the 
deeply sunk cups, the jointed stems, and the arrangement 
of the cups make the colonies resemble some firs, or the 
backbone of a little fish. Finally, the Plumularians are like 
little feathers, and have their cups placed at one side of the 
stem only. 

From this survey of the littoral Hydrozoa we may gather 
a general idea of the special peculiarities of these curious 
and beautiful animals. All the forms we have considered 
are colonial, living in communities often formed of an enor- 
mous number of individuals, which are mutually dependent, 
and are connected by a ramifying series of canals. In 
the next group of Coelentera the sea-anemones and their 
allies this colonial habit is less common in our seas, though 
even there colonies quite analogous to those of the sea-firs 
do occur. Again, except in Hydmctinia, we have found 
that the individuals of the colonies show little division of 
labour; we have nutritive persons, or hydroid polypes, and 
reproductive persons, sporosacs or swimming-bells, but with 
the exception already made, the hydroid members of any 
colony are all similar. Now in certain free-living Hydrozoa, 
which are abundant in warm seas, but very inadequately 


represented in our own, division of labour is carried to a 
much greater extent than in Hydractinia, and we have 
floating colonies formed of many different kinds of persons. 
These constitute the Siphonophora, and are exemplified by 
such forms as the " Portuguese man-of-war," which is some- 
times brought by the Gulf Stream to certain parts of our 

Another interesting point about our littoral Hydrozoa is 
that, as we have already pointed out, they show a consider- 
able range of variation in regard to the power of forming 
a skeleton. While some, like Clava, form scarcely any 
skeletal substance at all, in others, as for instance the 
"bottle-brush," the tough coat is much more conspicuous 
than the living zooids. But whether the coat be well 
developed or not, it should be noted that it is always 
horny, and never made of lime. There are a few Hydrozoa 
which form limy coats (corals), but these do not occur 
round our coasts. 

Lastly, we should note the relation of the zoophyte 
colonies to the tiny swimming-bells so abundant in our 
seas in late summer and early autumn. We have seen that 
these medusoids arise from zoophyte colonies, and are the 
reproductive persons of those colonies, and we have seen 
also that while some zoophytes give rise to medusoids, 
others bear sessile sporosacs. In some cases, as in the 
Sertularians and Plumularians, this latter condition prevails 
in a whole family ; while in other cases, as in the Campanu- 
larians, closely related forms display the two conditions. 
There seems no doubt that the production of swimming- 
bells is the more primitive condition, and that this power 
has been lost by such families as the Plumularians and 
Sertularians. Probably its loss is associated with the fact 
that the bells are very liable to be swept away by strong 
currents to localities quite unsuitable for the hydroid stages, 
and that distribution by means of minute larvae is as 
effective and much less costly than the production of 
swimming-bells. Nevertheless, we have forms like Obelia 
geniculata and Campanularia flexuosa, which seem to live 
under quite similar conditions, and are both extraordinarily 
abundant; and of these one bears sporosacs and the other 
true medusoids. Therefore, though we have much reason 


to believe that the condition of each is an adaptation to its 
own particular surroundings, yet we are unable to say how 
the surroundings differ, or wherein the adaptation consists. 
Nor can we say that the difference is associated with some 
other structural peculiarity, for as yet it is not possible to 
point out any constant difference between those zoophytes 
which produce medusoids and those producing sporosacs, 
apart from this prime difference. It is the constant occur- 
rence of phenomena like this which makes shore life so 
interesting, and its study so helpful to those especially 
whose scientific training has been largely that of the 

Though we cannot tell whether a hydroid colony will 
produce sporosacs or medusoids, apart from the actual 
experience which shows us what it does produce, yet it is 
interesting to note that there is a permanent structural 
distinction between the swimming-bells of the Calypto- 
blastea and those of the Gymnoblastea, so that we can 
determine the nature of the colony from which any par- 
ticular swimming-bell has arisen. We cannot here describe 
in detail these differences, but may note that in the former 
case the reproductive elements are produced in the rnanu- 
brium, or clapper of the bell (cf. Sarsia), while in the latter 
they arise in the course of those radial canals of which 
mention has been made (p. 47). Both kinds of medusoids 
are common in our seas, but in most localities those of the 
species of Obelia are perhaps commonest of all. They may 
be recognised by their peculiarly flattened shape, and the 
short distinctly four-lipped manubrium. The tentacles are 
short and numerous, and the four sets of reproductive 
organs are very distinct. The size varies from about that of 
a sixpence to that of half a crown, and the creatures resemble 
transparent plates rather than bells. Another very common 
swimming-bell, that of Clytia johnstoni, is shown in Fig. 90, 
p. 326. It differs chiefly from that of Obelia in having only 
four tentacles. 

We shall conclude this chapter by giving a table which 
may assist the student in the identification of the common 


CCELENTERA. Hollow-bodied animals with tentacles and sting- 


Sub-class. HYDROMEDUS^;. 

Order I. GYMNOBLASTEA. Zoophyte colonies in which the horny 
investment, if present, does not form cups for the zooids. 

Tentacles scattered and 

Tentacles thread-like. 

very numerous. J ava " 

Tentacle in two circles. Tulularia. 
Tentacles in one circle. 

. ^ 

Zooids not all similar. ) 

{Colonies produce sessile \ 
sporosacs. / oryne 

Colonies produce free ^ 
medusoids (Sarria). ) 


Clava. Two common species, C. squamata forming dense clusters on 
weed, C. multicornis with scattered individuals usually on 

Coryne. A common species is C. piisilla, a small, rather delicate 
species, with slightly branched stems marked with rings. 
Tentacles, about thirty, in many circles ; zooid long and 
slender, scarcely tapering below. 

Syncoryne. A common and conspicuous species is S. eximia which 
forms bushy tufts on weeds. Stems often several inches in 
length, smooth save for a few annuli at the base, profusely 

Tubularia. In T. indivisa the stems are long, unbranched, and 
smooth. Between the upper and lower circle of tentacles are 
inserted the grape -like bunches of sporosacs. 

Hydradinia. In H. echinata the colony forms a pinkish crust on 
shells inhabited by hermit-crabs. For description see text. 

Order II. CALYPTOBLASTEA. Sea-firs, in which the zooids are 
placed in horny cups. 


Fam. Campanularidee. ( Cly * ia > Obelia, Campanularia are not dis- 

Cups bell-shaped and \ tin g sh ed by any peculiarity of the 

stalked colonies as a whole, but only by their 

I reproductive persons (see pp. 50-52, 60). 

Fam. Campanulinidfe. } 7 n W.LI. j- , 

Cups ovate and coni- Opercularella. With a distinct operculum 
calf stalked. J (ee below). 



Fam. Lafoeidse. Cups 
tubular and sessile. 

Fam. Halecidse. Cups 
in two rows, tubular 
and sessile, borne on 
projecting processes of 

Fam. Sertularidte. Cups 
sessile, sunk in the 
stem, usually in two 

Fam. riumularidfe. Cups 
sessile, on one side of 
stem only, "nemato- 
phores" present. 

Cups very numerous, springing 
from all sides of the stem. 

Halecium. Stems peculiarly stiff and rigid. 

Cups alternate, with \ 
toothed margin and Y Sertularella. 
an operpulum. 

Cups opposite, stem | 
made up of V-shaped j- Sertularia. 
joints. J 

Cups tubular, on one \ 
side of stem only, in j- Hydrallmania. 

Cups deeply sunk, \ 
branches confined to V Thuiaria. 
upper part of stem. J 

Plumularia. Nematophores distributed 
along the stem and branches. 

Fam. Campamilaridce. 

Genus Obelia. Contains a number of species, of which the com- 
monest is Obelia geniculata. Height about one inch. Stems 
upright, zigzag, connected at base by creeping stolons, 
jointed, with stalked cups at the joints. Margins of cups 
smooth, stalks ringed. 

Genus Clytia. In Clytia johnstoni, which is very common, the 
stems bear a single terminal cup. Stems ringed at top and 
bottom, but not in middle ; edge of cup with ten to twelve 
teeth. Gonothecce either on stems or on basal stolon. 

Genus Campanularia. The commonest species is Campanularia 
flcxuosa. Stems slender, branched, flcxuous, about one inch 
high. Cups large, tapering below, with long ringed stalks. 
Gonothecre large. 

Fam. Campanulinidce. 

Genus Opercularella. In 0. lacerata the stem is under one inch in 
height, erect, slender, ringed throughout ; cups few, on ringed 
stalks. Cups with segmented margin, the segments being 
capable of closing over the opening like a lid (operculum). 
Gonothecce large. 


Fam. Lafoeidse. 

Genus Lafoea. In L. dumosa height may reach four inches, stems 
erect and irregularly branched, or simple and creeping, cups 
tubular and numerous, arising from all sides of the stem. 

Fam. Halecidce. 

Genus Halecium. In H. halecinum ("herring-bone" coral) height 
may reach ten inches. Stems rigid, much branched. Cups 
sessile in two rows on projecting processes, alternate, tubular. 
Gonothecfe on upper surface of stems, broad and truncate 
above, with tubular orifice at side. 

Fam. Sertularidoe. 

Genus Sertularella. In S. polyzonias the cups are urn-shaped, 
bulging below, with a divergent four-toothed aperture. Gono- 
tliecre shortly stalked and large. Stems slender, much but 
irregularly branched. 

Genus Sertularia. In S. pumila the sterns are loosely branched, 
the gonothecse have a tubular rim. 

Genus Hydrallmania. In H. falcata ("sickle -coralline") the 
stems are about a foot long, slender, and with spirally- 
arranged branches. Gonothecae yellow and tubular. 

Genus Thuiaria. In Thuiaria thuia ("bottle-brush") the stem, 
which may be one foot in length, bears a cluster of branches 
at the top. Cups in two rows. 

Fam. PlumularidtB. 

Genus Plumularia. In P. setacea the slender, delicate stems are 
about one inch in height, the plumes arise separately from 
the creeping stolon. Joints of branches alternately long and 
short, zooid-cups placed singly on the long joints. For 
nematophores, see figure. Gonothecoe with long tubular 


The Sponges and Sea-firs described in this chapter are so common 
that they may be expected at almost any part of the British area, 
where the conditions are at all favourable. Their relative abundance 
at different places varies considerably, however. Thus Hydractinia 
echinata, which is extraordinarily abundant at St. Andrews and in 
the Firth of Forth, is much less common in the South and West. 
Again, at places like Torquay and Penzance, not only may many 
other species be expected on the shore in addition to those mentioned, 
but a happy chance may furnish the "Portuguese man-of-war" 
(Physalia), to which reference has been made above, and other beau- 
tiful free-swimming forms, swept in by ocean currents from the open 
sea. Though generally vspeaking the South and West are richer in 
Hydrozoa than the North and East, yet there are one or two forms 
which occur in the latter and not in the former localities. The 
interesting "bottle-brush" (Thuiaria thuia}, for example, is said to 
be rare off the coasts of Cornwall and Devon. 



Differences between sea-anemones and zoophytes Four common sea- 
anemones, their habits and characters Variation in sea-anemones 
"Dead men's fingers" in life and after death The sea-pen 
The Jelly-fishes Life-history of Aurelia Relation to Lucenaria 
The Ctenophora, or "iridescent fire-globes." 

SO far we have been concerned with the simplest of the 
Coelentera, where any complexity which may occur is 
the result of the combination of individuals, and not of the 
characters of the individuals themselves. Furthermore, as 
we have repeatedly emphasised, the individuals are always 
small, often very small, and alternation of generations is 
always clearly indicated, though there is a tendency for it 
to become suppressed. In all the cases we discussed where 
the alternation disappears, it is the active medusoid stage 
which is lost. The second class of Coalentera, which we 
are to consider in this chapter, is in many respects very 
sharply contrasted with the Hydrozoa. The individuals are 
often large ; colonies, in our seas at least, are relatively less 
frequent; the structure of the individual is more complex 
than in the Hydrozoa; there is either no trace of alternation 
of generations, or, where it occurs, the active jelly-fish stage 
tends to be accentuated at the expense of the stationary 
stage. This class is often called the Scyphozoa, and is held 
to include the sea-anemones and their allies (Anthozoa), and 
the big jelly-fish. By some authorities, however, the jelly- 
fish are placed in a separate class. As we shall be very 
little concerned with the jelly-fish we need not discuss the 
question of their position, but may merely emphasise their 
distinctness from the swimming-bells of the Hydrozoa, 
which are much smaller and less complex. 




Of the Scyphozoa the most interesting to most people are 
undoubtedly the sea-anemones, with which we may con- 
veniently begin. The anemones are almost always beautiful 
and brightly coloured, they live well in captivity, they are 
common and conspicuous; facts which easily explain their 
popularity, even with persons who shrink from sea animals 
in general as always slimy and possibly noxious. Their 
popularity has been assisted by the fact that in Gosse's 
British Sea-anemones and Corals we have a readily accessible 
book which, from its wealth of illustration and clear 
descriptions, enables the veriest neophyte to name his finds. 
Unfortunately, the anemone-lover whose habitation chances 
to be on the East Coast is not likely to find a great variety 
of forms. While the rocky, wave-swept shores of Devon 
and Cornwall are often veritable gardens of sea-flowers, our 
sandy beaches produce a few species only, and these the 
commonest and hardiest kinds. On the shore rocks of the 
East Coast we cannot hope to find more than four species, 
and among these we miss the beautiful Anthea cereus, which 
at so many spots on the South and West flourishes in 
gorgeous beauty between tide-marks. 

We may take first the most abundant and obvious of all 
our native anemones, the smooth anemone (Actinia mesembry- 
anthemum, Fig. 23), which can live everywhere and any- 
where, asking only a firm basis of attachment, and a situation 
between tide-marks. If you find a clear pool containing a 
specimen in full expansion you may proceed to study the 
general characters of sea-anemones. The general " polype " 
shape is of course 
obvious, the body con- 
sisting of an attached 
base, an upright 
column, and a disc 
bearing a central 
mouth surrounded by 
numerous tentacles. 
Touch the tentacles 
with your finger, and 
you will find that 

they have a peculiar FIG. 23. Common smooth anemone (Ac'inia 
Stickv feelino- dllP to mesembryanthemum). Note the beads at the 
J o> " base of the tentacles. 


the ejection of their numerous stinging-cells, which are 
too weak to pierce the skin. When molested the anemone 

a 1 es not shrink down in the way in which the hydroid 
Dphytes do, but contracts a circular muscle at the top of 
B column, and pulls the tentacles inwards at the same 
ae. The result may be compared to the closing of a bag 
drawing a string run in its margin. The mouth is a 
longitudinal slit, whose walls are much grooved. Of the 
grooves two are more distinct than the others, and con- 
stitute the " siphonoglyphes." which are structures of 
considerable interest to the student of form. It is not 
easy to get a practical notion of the internal anatomy 
of a sea-anemone without subjecting it to special treat- 
ment; but sometimes some of the more transparent 
species can be studied in the living condition by holding 
expanded specimens in a glass jar up to the light. The 
more important points may be briefly summarised as follows. 
The mouth opens into a short gullet, which itself opens 
into the general cavity ; this gullet can be clearly seen when, 
as often happens, captive anemones partially turn themselves 
inside out, and is produced by an infolding of the body-wall. 
The gullet does not hang freely in the general cavity, for a 
number of partitions or mesenteries run from it to the 
body-wall, so that a cross-section of the upper part of a 
sea-anemone would show a central chamber surrounded by 
radial chambers. These radial chambers are traversed by 
other narrow mesenteries which project from the body-wall, 
but do not extend inwards so far as the gullet. On the 
mesenteries are borne the reproductive organs, and also 
certain tangled threads, supposed to be of importance in 
digestion. These are often seen when an anemone is 
ruptured in the attempt to remove it from a rock surface. 
In certain anemones, but not in the smooth anemone, 
the mesenteries also bear long, slender threads, crowded 
with stinging-cells, and capable of being shot out by 
pores in the body-wall. In Actinia these acontia seem 
to be functionally replaced by the " batteries of stinging- 
cells," which form the row of blue beads visible at the 
base of the tentacles. The chief points of contrast 
between a sea-anemone and a hydroid polype are : the 
presence in the former of a distinct gullet, of mesenteries 



or partitions, and of "digestive filamerrts," the tangled 
threads mentioned above. 

As to the special characters of Actinia mesembryan- 
themum, note the very smooth column, which is always 
short relative to its diameter; the rather short tentacles, 
which number about 200, and usually in the expanded 
condition curl over the margin of the disc. The mouth is 
elevated on a blunt cone, and the row of blue beads is very 
characteristic. There is always a narrow blue edging round 
the base, but in the other parts of the body the colours are 
very variable. The three common tints are dark red, olive- 
brown, and green, but in many cases the column is streaked 
and spotted with lighter colours. This anemone lives well 
in captivity, and then often gives rise to numbers of tiny 
semi-transparent young, which make the daintiest of pets. 
As sea-anemones are so familiar, it is, however, probably 
unnecessary to expatiate on the habits at length. Gosse 
names and describes a number of varieties of the smooth 
anemone, but perhaps the most important point for us is to 
emphasise the great adaptability of sea-anemones in general. 
They are, of course, of relatively low organisation, and seem 
capable of varying in harmony with their environment to a 
very marked extent. The variability is often displayed by 
modification in colour, which we have, perhaps, no reason to 
regard as adaptive, but it is also often shown in other 
characters. This is well seen in the next sea-anemone, 
Tealia crassicornis, the thick-horned anemone, which in 
abundance comes only next to Actinia. It inhabits both 
deep and shallow water, and between tide-marks sometimes 
lives in rock pools which never become dry, and at other 
times under overhanging rocks among gravel and sand. In 
these different situations it exhibits noticeable structural 
differences, while of colour differences there is an almost 
endless variety. 

What may be called typical specimens are to be found 
under sheltering stones where the sun does not reach. At 
low tide the anemones form an almost indistinguishable 
mass of stones and shell fragments, but are yet sufficiently 
alive to squirt vigorous jets of water at an intruding 
naturalist, at the same time cowering down yet more closely 
among the debris. If an attempt be made to remove the 


specimens, it will be found that they are attached, not to 
one smooth surface, but to a number of objects, in a fashion 
that makes them difficult to extricate without injury. 
Further observation in a neighbouring pool will probably 
disclose some other fully expanded specimens in which the 
characters can be studied. The anemone is characterised by 
the size of the base as compared to that of the column ; it is 
a low, flattened animal, with a diameter often of several 
inches. The tentacles are short, very thick, and not 
numerous ; they have none of the snaky appearance usually 

FIG. 24. Tealia crassicornis, the thick-horned anemone. Note the central 
mouth, and the stout, banded tentacles. After Tugwell. 

associated with anemones' tentacles. The surface of the 
column is covered by distinct warts or papillee, to which 
shells and stones are attached. The colours vary, but reds 
and greens are common, while the tentacles are banded 
with white, and have very distinct reddish bands round 
their bases, which extend over the disc towards the mouth. 
Though the majority of the thick-horned anemones found 
between tide-marks are of this type, yet in those narrow 
rock-clefts which are swept clean by the tidal currents 
but never completely emptied, another variety occurs. At 
North Berwick, for example, the shore rocks are hollowed 
out into many fissures and crevices, and it frequently 
happens that a cleft, which from above seems narrow 
enough, widens out below into an extensive deeply shaded 


pool. If by any means you can wedge yourself down the 
cleft, and obtain a foothold in the cavern beneath, you 
may see dozens of specimens of Tealia crOSsicornis in full 
expansion, and in almost every variety of tint. They 
attach themselves to the perpendicular rock-walls, and, 
apparently as a result of this mode of attachment, show 
a much more typical " anemone-shape " than their flattened 
brethren of the tidal pools. That is, the column reaches a 
height equalling the diameter of the disc, and is truly 
columnar; whereas in the other form it is short or squat. 
Again, these deep pools contain no shell sand or gravel, 
and the anemones are in consequence destitute of covering, 
while the functionless warts have become small and incon- 
spicuous. The colouring is brilliant, and it not infrequently 
happens that the tentacles are uniformly coloured through- 
out, or have merely a paler spot near the tip. In the 
commoner form they are distinctly banded, which, from the 
artistic point of view, is a much less effective scheme of 
coloration. A colony of such anemones, all of large size 
and all in full expansion, forms one of the most beautiful 
of the many beautiful sights of the shore, and I know 
few more fascinating occupations than that of successfully 
forcing one's self into these caverns, and while maintain- 
ing a somewhat uncertain foothold on the slippery sides, 
studying every detail of colour and form. The roar of the 
breakers at the mouth of the cleft, and the rush of water, 
now in and now out, adds the spice of danger to the 
occupation which is essential to fill up the tale of pleasur- 
able sensations. These anemones, unlike those in shallow 
pools, are easily detached without injury, but they rarely 
live well in captivity; they doubtless miss there the 
abundantly oxygenated water of their natural habitat. 
If the t de permit it is easy in that natural habitat to 
make observations on the diet. In spite of their frequently 
fragile appearance the anemones in general are far from 
having fairy appetites, and Tealia is especially voracious. 
It seems to have a special preference for crabs, and may 
often be seen disgorging the remnants of its victims. In 
a quiet pool, indeed, I have seen a regular heap of dejecta 
beneath the anemone a veritable kitchen midden on a small 
scale. It is interesting to note that the colour of the shell 



of the shore crab is changed by the digestive process from 
greenish to red a change which it is easy to imitate in the 
laboratory by immersing a fresh shell in dilute acid. Also, 
the hard shell has been rendered brittle and is easily 
pulverised. From these observations we might deduce the 
conclusion which has, indeed, been reached by experiment 
that the anemone secretes an acid digestive fluid. 

Next in order of abundance on the East Coast comes the 
cave-dwelling anemone (Sagartia troglodytes}, a form which 

in spite of its 
abundance is much 
more difficult to 
find than either 
of those already 
mentioned. If you 
are idly gazing into 
a shallow rock pool 
floored with varie- 
gated sand or fine 
gravel, you may 
as you gaze certain 

FIG. 25. The cave-dwelling anemone, Sagartia troglodytes, star-like patches 
Note the beautifully marked tentacles, and especially differentiate them- 

selves from the 

background by a regularity of shape, not to be ascribed to 
current action. If you touch these spots in order to 
investigate the matter, the star disappears, leaving an ill- 
defined hollow. Study this phenomenon still more closely 
by scraping the sand away with your fingers, and you will 
find a small sea-anemone, attached to the rock surface which 
floors the pool, and protruding its crown of tentacles through 
the sand. The attachment is relatively slight, and the 
anemone can be readily removed and placed in a clean pool 
or a collecting jar. It is very contractile, and by the time 
the process is completed will probably be reduced to the 
condition of a brownish button, partially invested in its 
own white stinging-threads (acontia), which are shot out in 
abundance as soon as it is touched. It rapidly recovers, 
however, and will probably soon unfold its tentacles, and 
display the variegated marking which gives them so deceptive 


a resemblance to sand. The column is long, often very long, 
and cylindrical, and in its upper two-thirds is covered by 
distinct suckers, to which fragments of stone and shell are 
often attached. On the other hand, in a sandy pool it is 
not uncommon to find specimens which, instead of being 
covered with isolated fragments of gravel, have a complete 
investment made of fine sand glued together by mucus. 
This can be peeled off, and leaves the smooth column below. 
The cave-dweller does not always live in sandy pools, but, 
as the name indicates, is often found in rock crevices. 
There the colours are brighter, the prevailing tint being 
greenish brown or grey-violet. They are also often abundant 
in the beds of young mussels which sometimes cover the 
flat surfaces of rocks. The young mussels are, as it were, 
embedded in a thick layer of silt, which intervenes between 
them and the rock surface. The anemones are attached to 
the rock like the mussels, and protrude their starry crowns 
through the layer of silt, while the shells of the mussels 
make a firm wall around them. If you look at such a young 
mussel-bed from a distance of a few feet, you will notice 
that the uniformity is interrupted by numerous rounded 
spaces, in which the silt and sand show out in contrast to 
the dark shells of the surrounding mussels. A close 
examination will show you that each gap is occupied by a 
flourishing Sagartia troglodytes. The sight is an interesting 
one, and suggests many problems. What does the anemone 
gain from the association? Is it a true case of an "animal 
association," or is it merely a chance that the same environ- 
ment should suit both? Does the anemone obtain any of 
those benefits somewhat vaguely summed up in the word 
protection, or is it that it shares the food of the mussels'? 
These are only a few of the questions one would like 

The cave-dweller lives so well in confinement, and its 
markings so well repay study, that a few should be taken 
home for the purpose. In one habit it differs remarkably 
from the two preceding anemones. They will rarely expand 
freely unless the base is firmly fixed, and as every aquarium 
keeper knows, they will never thrive unless they can be 
persuaded to attach themselves almost at once. The cave- 
dweller, on the other hand, rarely completely retracts its 


tentacles, and will often expand fully while lying loose in 
a jar. It never fixes itself very firmly, and the "cave- 
dwelling " habit is no doubt associated with the fact that it 
seems unable to cling tightly enough to resist wave-action, 
and must therefore seek protected crevices. 

y\s to p,r>1nrfl.t,inTi T though the actual tints of column, disc, 
and tentacles show much variation, yet there is considerable 
constancy in the markings, which constitute important 
specific characters. The column is marked with light 
stripes most conspicuous towards the base, the disc is 
beautifully marked with radiating bands, each band being 
patterned in dark and light tints, and at the base of the 
tentacles there is a black mark of the shape of a B, the 
curves being directed towards the mouth. This B-mark is 
eminently characteristic of Sagartia troglodytes. Finally, 
the tentacles themselves are banded in dark or light tints, 
and are of much importance in producing the resemblance 
to sand so characteristic of the expanded anemone. 

There are a number of other species of Sagartia, mostly 
showing some indication of the elaborate patterns of S. 
troglodytes, but these do not occur, between tide-marks at 
least, on the East Coast, and naturalists living on the West 
may be referred direct to Gosse's book. 

The last of our East Coast species is Actinoloba dianthus, 
the plumose anemone, a form which is often said to be an 
inhabitant of deep water, but which in sheltered places is 
not uncommon between tide-marks. On the Clyde it has a 
special preference for the supports of piers, and there occurs 
in the most gorgeous profusion, clustering thickly about the 
whole length of the uprights; the smaller specimens between 
tide-marks, the larger further down, so that their pale tints 
gleam faintly through the green depths of water, and the 
outlines of their translucent bodies are hardly discernible in 
the dim light. In such situations they reach a great size, 
having a column some six inches long, with a disc of several 
inches in diameter. But it is only under exceptional cir- 
cumstances that such specimens can be seen close inshore, 
certainly not as a rule in the shallow waters which fringe 
the beach on the East Coast. There one cannot look for 
specimens of more than an inch or so in height, and as 
already mentioned, these usually occur in sheltered places 


only. Often they are found under overhanging rocks or in 
deep and dark rock crevices, but on the Firth of Forth, on 
the other hand, I have found numerous specimens growing 
fully exposed to view on loose stones on the shore. In this, 
as in many other cases, we require more evidence before we 
can determine what it is that renders a locality suited to the 

Fia. 26. The plumose anemone (Actinoldba dianthus). Note the "parapet " 
or ridge, beneath the frilled disc. After Tugwell. 

needs of the species ; it may be a protection against violent 
wave-action which is necessary, or the abundance of some 
particular kind of food, or a constant supply of pure water, 
or some other unknown environmental condition. Certain 
it is that this is a local anemone, abundant where it occurs, 
but often absent from apparently suitable spots. It is also 
very variable in colour, being sometimes white, sometimes 
yellow, sometimes flesh-coloured. The fact that all three 
colour varieties may occur in the same situation seems 


against the supposition that the colour variations are 
"adaptive," or directly determined by the environment. 

As to the general characters of this anemone, notice the 
smooth cylindrical column, with no trace of suckers, but 
with minute pores, from which acontia may be emitted. 
The upper margin of the column is thickened, and forms a 
"parapet," which is separated from the frilled disc by a 
groove or fosse. It is this frilled or puckered disc which is 
so distinctive a character of the anemone. It is very thin, 
and bears very numerous small tentacles, banded with white, 
the whole appearing like the "foliated crown of a palm 
tree." The mouth is grooved, usually has its margins highly 
coloured, and has one, two, or three siphonoglyphes (see 
p. 66) a very interesting range of variation, which also 
affects the mesenteries internally, and which you should not 
fail to notice. 

The plumose anemone lives well in captivity, and is 
remarkably active for a sea-anemone, continually changing 
its position, but generally keeping very close to the surface 
of the water, where the oxygen must be most abundant. 
Often in the course of its movements it leaves a fragment 
of the wide base behind it, and this fragment may grow into 
a new anemone. Both in captivity and in natural conditions 
it has a curious habit of distending a part of the body with 
water while the disc and tentacles are retracted, and then 
drops in a limp and flaccid way from its point of attachment 
a translucent shapeless mass. In the young specimens 
the tentacles are not so numerous, and the disc is not dis- 
tinctly frilled, but even at this stage it is hardly possible to 
confuse it with any other anemone. 

Related to the sea-anemones are the Alcyonarians, which 
are represented on the shore by Alcyonium digitatum, or 
"dead men's fingers." It is a colonial form, consisting of a 
number of small polypes embedded in a fleshy mass. After 
death the fleshy substance is much more conspicuous than 
the polypes, and in the condition in which it is tossed on 
shore after storms is not a pleasing object, for there is no 
beauty of form, and the colour is too " fleshy " to be pre- 
possessing. In the living condition, on the other hand, with 
its glassy polypes fully expanded in a quiet pool, it is a 
singularly beautiful creature, and one very well worth study. 


Though perhaps not a strictly littoral form, in sheltered 
situations large colonies may often be found between tide- 
marks, usually in company with Actinoloba diantlms. 
Probably in both cases shelter from violent wave-action is 
indispensable, and it is only where this is attainable that 
life in the littoral zone becomes possible for either. Small 
colonies with a diameter of perhaps J inch to J inch are 
often common in rock pools, but the full-grown colonies form 
bulky lobed masses, several inches in height and diameter. 
The fleshy substance (ccenosarc) is yellow or pinkish, but 
the polypes themselves are clear and colourless. They each 
bear eight tentacles, while sea-anemones have their tentacles 
in multiples of six. Further, each tentacle is pinnate, or 
fringed with small processes arranged like the barbs of a 
feather, the result being to produce a beautiful star-like 
crown when the tentacles are spread out in the water. The 
internal anatomy generally resembles that of sea-anemones, 
and some of its details may be made out through the 
transparent body-wall. Each polype is placed in a small 
cavity of the pulp or ccenosarc, into which it may be 
retracted. The coenosarc contains a series of canals, which 
place the polypes in communication with one another, and 
is strengthened by limy spicules scattered through its 

Eelated to Alcyonium is the very beautiful sea-pen (Pen- 
natula phospJiorea), which occurs freely in deep water, and 
may sometimes be obtained from the fishing-boats. It is in 
the form of a fleshy plume of red colour, the upper region 
bearing numerous polypes like those of Alcyonium. It has 
a central rod of lime in its lower region, and so leads up to 
the red coral of commerce, which is in reality the supporting 
axis of a fleshy coenosarc bearing numerous polypes like 
those of Alcyonium. It thus differs markedly from the 
majority of the " corals " which are made by the aggregation 
of many limy cups containing polypes ; that is, are built on 
the same plan as the horny skeleton of a Campanularian. 
In the red coral there are no cups, for the polypes are placed 
in a fleshy ccenosarc, as in Alcyonium^ this being removed 
during the process of preparation of the coral. It may 
perhaps be well at this point to spare a few words to repeat 
that "corals" are the hard parts of Ccelentera, and there- 


fore have nothing whatever to do with Insects, so that that 
artless little metaphor about the devotion to duty exhibited 
by the "coral insect," which has rooted itself so deeply in 
the mind of the popular orator, is sheer nonsense a not 
uncommon characteristic of oratorical "scientific analogies." 
We have already mentioned the fact that the big "jelly- 
fish," as distinct from the delicate swimming-bells, appear 
to be related to the sea-anemones and Alcyonarians rather 
than to the Hydrozoa. Of these jelly-fish only some three 
or four are common round our coasts, but these often occur 
in such countless numbers that they are more or less 
familiar to everyone. We shall only describe one of these 
in detail, choosing it because certain stages in its life- 
history are to be found on the shore rocks. This is Aurelia 
aurita, easily recognised by four horseshoe-shaped purple 
bands seen on its dorsal surface, and recommended by the 
fact that it can be handled without danger of being stung, 
so far, at least, as my experience goes. Let us begin with 
the larva, which is certainly minute and harmless enough. 
It is a little creature called a hydra-tuba, is pure white, and 
is to be found attached to rocks by one end of its body, 
while the other is furnished with a mouth surrounded by 
waving tentacles. It is, you may say, merely a polype of 
a type with which you are now quite familiar. This is 
indeed the case, but it has been shown that, small and 
simple as it appears, the hydra-tuba in certain points 
suggests connection with the sea-anemones and not with 
the Hydrozoa. It is usually not more than one-eighth of 
an inch in height, and is to be found far out on the rocks. 
In late summer it undergoes certain changes presently to 
be described, but, oddly enough, these changes may some- 
times be arrested for an apparently indefinite period. I 
have seen captive specimens which the owner assured me 
had been kept for several years without showing any signs 
of change. Under natural conditions, however, the little 
hydra-tuba elongates and becomes marked by a series of 
transverse lines, so that it appears like a pile of saucers. 
A little later the top "saucer" floats off, turns over, and 
becomes a little jelly-fish which grows rapidly and becomes 
an Aurelia. The same thing occurs with the lower 
"saucers" of the pile, so that the tiny hydra-tuba gives 


rise to a number of large jelly-fish. There seems almost 
no limit to the size a jelly-fish may reach, but specimens 
of Aurelia aurita round our coasts commonly vary from 
six inches to a foot or more in diameter. If this be com- 
pared with the minute size of the hydra-tuba, and the 
relative sizes of the sea-firs and their swimming-bells be 
recalled, it will be clear what is meant by the statement on 
page 64 that in the alternations of generations seen in the 
jelly-fish, the free-swimming stage is accentuated at the 
expense of the sedentary stage. 

To get a general idea of the structure of a jelly-fish, some 
specimens of Aurelia aurita should be obtained. They are 
usually very abundant in August, and care should be taken 
to obtain one or two living specimens not too large to be 
readily observed. The living animal is much more attractive 
than the flattened, half-melted creature so often left on the 
beach by the ebbing tide. In it the umbrella is sharply 
curved, not flat as in dead or relaxed specimens, and its 
slightly inturned margin is furnished with numerous slender 
tentacles of perhaps a couple of inches in length; after 
death these are always much contracted and become incon- 
spicuous. The manubrium, or clapper of the bell, is divided 
into four somewhat short arms, having the mouth opening 
in the centre. You should not fail to notice that in some 
others of our jelly-fish (Oyanea, Chrysaora) the tentacles 
are very long, and so are also the frilled and puckered arms 
of the manubrium. As to the other characters of Aurelia^ 
the four horseshoe -shaped reproductive organs are very 
obvious, and by turning the animal over you see that 
beneath each of these is a little pit, opening to the exterior 
by quite a distinct orifice. These are often called "respira- 
tory" or genital pits, but are believed by some authorities 
to be remnants of larval structures. There is no "veil" 
like that of the swimming-bells, but the jelly is traversed 
as in them by a series of radial canals, in this case rendered 
very obvious by their violet tint. At the margin of the 
bell there are eight sense-organs, or " tentaculocysts," which 
are easily made out. 

Related to Aurelia there are, as already mentioned, some 
other jelly-fish, often of large size, and sometimes with very 
distinct stinging power. The very large forms are more 



likely to be found on the West than on the East Coast, 
and in any case are somewhat beyond our scope. There is a 
small, delicate creature, however, to be found on the rocks 
which is related to the jelly-fish, though it differs from 
them markedly in appearance. This is Lucenaria, or as it 
is now called, Halidystus odoradiatus. It is, perhaps, 

rather umbrella -shaped 
than bell -shaped, but 
there is nothing to re- 
present the stick of the 
umbrella that is, no 
manubrium and the 
region of the body oppo- 
site the mouth is pro- 
longed into a short stalk 
which is attached to 
weed in the pools. The 
free margin of the um- 
brella bears eight groups 
of short tentacles, and 
the mouth has the usual 
central position. It is 
an animal which is diffi- 
cult to find, though perhaps it is not very uncommon, and 
reaches a size of one inch or so. The difficulty is largely 
due to its delicacy and transparency, and to the fact that 
in colour it usually resembles the weed to which it is 
attached. It shows no trace of alternation of generations, 
and is interesting on account of a certain general resem- 
blance to a hydra-tuba, so that one might suppose that it 
was a larval jelly-fish which had forgotten to grow up, and 
had become adapted for a sedentary life. It is not a 
perfectly stationary form, but possesses some power of 
moving about, and by attaching itself, first by the stalk 
and then by little marginal tubercles which alternate with 
the tentacles, can progress like a "looping caterpillar." It 
is a charming little creature, but, so far as my experience 
goes, not easy to keep in confinement. The colour is very 
variable, being brown, green, or claret-coloured, according 
to the colour of the surrounding weed. The accompanying 
figure should make the structure obvious. 

Fia. 27. Halidystus octoradiatus. 


The third and last class of the Coelentera includes a few 
beautiful free-living forms to be found floating at the surface 
of the sea. They may occasionally occur in the rock pools, 
but are more likely to be found in the open water, where 
they may be seen as little iridescent bells floating past the 
boat, in company with the tiny swimming-bells and the giant 
jelly-fish. These iridescent globes of jelly are members of 
the class CTENOPHORA, and differ markedly both from the 
true jelly-fish and from the swimming-bells. Two genera 
are not uncommon, Beroe and Pleurobrachia (see Fig. 93), 
sometimes called "iridescent fire-globes," or "sea-gooseberries." 
In the former the body is oval in shape with a wide mouth 
occupying the whole of the under surface, in the latter it is 
somewhat pear-shaped with a small mouth. When removed 
from the water both are colourless and delicately transparent, 
but when seen in active movement in the water both gleam 
with rainbow tints. This is due to the fact that the long 
axis of the body, from pole to pole, is traversed by eight 
bands of motile plates (four of these are shown in the figure), 
which in life are in constant movement, and propel the 
animal through the water, while by breaking up the light 
they also produce the changing play of colour. The structure 
of the body in both JSeroe and Pleurobrachia is a little 
complicated, so we need only notice further that the latter, 
but not the former, has two very long delicate tentacles 
which can be instantly retracted, or allowed to stream out 
like a long train behind the body (see Fig. 93). Both are 
most delicately beautiful animals in life, and should be 
looked for every summer, if only for the sake of their play 
of colours and graceful movements. As in the jelly-fish, 
most of the charm is lost after death. 

Perhaps it may be thought that in this and the preceding 
chapter we have eulogised ad nauseam the delicate beauty 
of a group of animals known to most people chiefly as 
"nasty stinging jelly-fish," but it is difficult to tear one's self 
away from a group whose members are adapted for so many 
different kinds of surroundings, and yet are essentially so 
simple and so uniform in structure. Their fascination, too, 
is enhanced by association, for many of them are "fair- 
weather animals," and all must be studied in the open air 
for their beauty to be fully appreciated. To anyone who 


knows them well, the very thought of Beroe, or medusoid, 
brings back a vivid recollection of summer days spent idly 
drifting over sunlit seas, when every rippling wave displays 
new shapes of beauty, new gleams of rainbow colour. The 
zoophytes similarly recall hours spent at the side of clear 
rock pools, yielding every moment new charms to patient 
search, new combinations of colour to the educated eye. 
Even those to whom animals as a rule appeal but little 
may be recommended to examine these sea-flowers, which 
are to be found in every pool, and may be studied there in 
all their beauty, without apparatus and without interference. 
They are also especially suited to those who shrink from 
comparative anatomy, as a rule, because it involves the 
death of the object studied, for most of the Ccelentera can 
only be properly investigated in the living condition, and 
will yield many of their secrets to the unaided eye of a 
patient observer. 

We have added to this chapter a table which may not 
only assist in the naming of specimens, but also in enabling 
the student to appreciate the number of different kinds of 
animals included in the group Coelentera. 

CCELENTERA continued from p. 61. 

Sub-class I. ANTHOZOA. Sedentary polypoid forms, simple or 

Order I. ZOANTHARIA. Tentacles simple, in multiples of six, 
sea- anemones. 

[ Tentacles slender. i . . 

Acontia present. \ Sa 9 art ' 
Column with suckers . -< 

Tentacles very thick. \ . ,. 
No acontia. Tealm ' 

Column quite smooth 

Tentacles very small 
and numerous, disc 
plumose. Acontia pre- 

Tentaclesnotverysmall, -\ 
with blue beads at their V Actinia. 
base. No acontia. J 

Order II. ALCYONARIA Tentacles feathered, in multiples of eight, 
all colonial. 

Coenosarc lobed, with scattered spicules . . Alcyonium. 

Ccenosarc pen-shaped, with a central axis . . Pennatula. 


Sub-class II. SCYPHOMEDUS.E. Jelly-fish with subgenital pits and 
no velum or veil. 

Order I. DISCOMEDUSJE. Active forms with complicated life-history. 
Four horseshoe-shaped genital organs . . . Aurelia. 

Order II. LTJCENARIJE. Sessile forms . . Ealidystus. 

Class III. CTENOPHORA. Free living forms with eight rows of 

Two tentacles and small mouth . . . Pleurobrachia. 

No tentacles and wide mouth . . Beroe. 


Class I. HYDROZOA (Chap. II.). 

(a) Gymnoblastea, polypes without 
protective sheath, e.g. Clava and 
^ -, TT -, j other common zoophytes. 

A. Order Hydromedus* j (i) C alyptoblastea, polypes placed in 
cups, e.g. Obelia and other com- 
mon sea-firs. 

B. Order Siphonophora . 

Class II. SCYPHOZOA (Chap. III.). 

A. Sub-class ANTHOZOA. 

1. Order Zoantharia sea-anemones and corals. 

2. Order Alcyonaria "dead men's fingers," sea-pens, etc. 

B. Sub-class SCYPHOMEDUS^:. 

Various orders, including the large jelly-fish and Haliclystus. 
Class III. CTENOPHORA. Free-swimming forms like the "sea- 
gooseberries" (Beroe), etc. 


The sea-anemones described in this chapter have been those of the 
East Coast, which is poorer in species than any other part of our area. 
It is not possible to name all the common anemones of the South and 
West, but a few notes may be given. In most places on the West the 
beautiful Anthea cereus, an anemone with smooth column and non- 
retractile tentacles which occurs in a brown and a green variety, is 
common. It is especially common on the coasts of Devon ; north 
of Devonshire, so far as my experience goes, the brown variety is 
commoner than the green, which is much the handsomer. Again, 
while at Alnmouth, St. Andrews, and on the shores of the Firth of 
Forth, Sagartia troglodytes is excessively common, it is probably less 
common on the South and West is certainly rendered less con- 
spicuous by the occurrence of many other somewhat similar species. 
At Mill port, for instance, Sagartia miniata, which has the outermost 
row of tentacles with a scarlet core, is one of the commonest anemones 
of the pools. Another species, Sagartia bellis, or the daisy anemone, 
is very common on the coasts of Devon and Cornwall. 


Different kinds of worms Nematodes Polychaetes External appear- 
ance of Nereis Structure of the fisherman's lob-worm Habits 
of worms Common shore worms The scale-worms, or Polynoids 
The leaf-worms, or Phyllodocids. 

fT^HE group of " worms " is an exceedingly large one, and 
_L includes a great number of forms not closely related to 
one another. Many of these are, however, small or rare, 
and need not trouble us here, so that we shall consider in 
detail two sets only the ribbon-worms (Nemertea) and the 
bristle-worms (Chaetopoda). Two other sets the round- 
worms (Nematoda) and the sea-mats (Polyzoa) are almost 
certain to be also encountered on the shore, and should be 
briefly referred to. The Polyzoa will be discussed after 
we have studied some more representative forms, but the 
Nematodes may be dismissed in a few words. 

In turning over stones on the shore, in search of nobler 
prey, one not infrequently comes across little white or 
almost transparent worms, which move with an active 
wriggling motion, and are rounded in cross section. They 
are especially abundant in pools containing decaying organic 
matter or odoriferous mud. These are round worms, or 
Nematodes, harmless enough in this case, but nearly related 
to some of the most dangerous parasites of man. Almost 
always of this dead white tint, there is s- mething in their 
very appearance which suggests their degraded and repulsive 
mode of life. In spite, therefore, of the fact that they 
exhibit many points of zoological interest, we may allow 
our instincts to guide us in passing them by, especially as 
their small size unfits them for our purposes. As these 



purposes are the acquisition of a practical knowledge of the 
structure of worms, we shall begin with the bristle-worms, 
or Chsetopoda. They are more highly differentiated than 
the ribbon-worms, are often of considerable size, and are 
easy to examine and dissect. 

The Chsetopoda (or " bristle-feet ") include two main sets of 
worms the marine forms (the Polychaetes), worms usually 
with many bristles, arranged on lateral outgrowths of the 
body (the parapodia or feet), and the Oligochsetes, worms 
like the common earthworm, living in earth or in fresh 
water, and having only few bristles. It is the marine 
worms only with which we are concerned here. 

The first step is, of course, to find the worms, but this is 
considerably easier than in the case of the historic hare. 
There is no shore so barren and desolate that it does not at 
some point or other show traces of the bristle-worms. On 
the mud-flats at the mouths of the rivers, on the smooth 
sandy shore at the edges of the rocks, or in the sandy bays 
in the middle of the rocks, one finds in abundance the 
"castings" of the common lob-worm. The dark seaweed 
thrown up by the breakers nearly always bears upon its 
fronds the little coiled dead-white tubes formed by the tiny 
Spirorbis. Among the debris which accumulates at tide- 
mark, a careful scrutiny will almost always reveal the neatly 
made tubes of Terebella decorated with particles of shell 
and stone, and encircled at the tip by a fringe of stiff sandy 
threads. The shore rocks are often in places covered with 
masses of the sandy tubes of Sabellaria, which look them- 
selves like an outcrop of porous rock. We might, indeed, 
continue the list almost indefinitely, but let us first choose a 
typical form for closer study. 

In turning over stones on the rocks between tide-marks, 
especially in slightly muddy pools, you are almost certain 
sooner or later to dislodge the worm for which we are 
seeking (see Fig. 28). When disturbed by the removal of 
the stone under which it has been lurking in an ill-defined 
burrow, it swims away with a peculiar wriggling motion. The 
colour is brown or greenish, and there is usually a faint but 
distinct metallic sheen. The length may be as much as six 
inches, but in forms from shallow water it is likely to be 
considerably less. The upper surface is arched, the lower 



flat with a distinct median groove, and the worm is uniform 
throughout its length, tapering towards the posterior end. 
It is very distinctly ringed, each ring bearing a pair of 
small lateral outgrowths, or parapodia, 
which carry bristles. A worm exhibiting 
these characters is pretty sure to be a 
species of Nereis, and most probably N. 
pelagica. Catch one or two of the largest 
you can find, and place them in a bottle 
with seaweed and clean water. They are 
not easy to keep in confinement, and will 
probably not live longer than a day or 
two, but this is long enough to observe 
some of the habits, the method of swim- 
ming, and so forth. If it is not desired to 
keep them alive, they may be killed at 
once by dropping direct into methylated 
spirit or formalin. 

After death, whether this be due to 
natural causes or to artificial means, you 
may proceed to your examination. This is 
most easily done by making at once a 
drawing of the animal, a practice which 
should be the invariable rule. The very 
act necessitates far closer observation than 
is likely otherwise to be given; the relative 
slowness of the process impresses the facts 
firmly upon the memory; the drawing, 
however rough, forms afterwards a most 
FIG. 28. Nereis peia- valuable record of the work done ; and 
OT^rostomiui^witti fi Iia U v > i n accordance with a familiar 
its small feelers and psychological rule, the concentration of 
peSmiumblfnd attention necessary to produce an ac- 
it with four pairs of curate drawing will intensify a thousand- 
cirri, but no feet. , , , , , , , . % . 

told the pleasure obtained irom your 


As to the details of the process, my own experience is 
that an artist's sketching -block of small size, where the 
sheets can be torn off as they are used, is more convenient 
than a book. The sheets can be kept in a portfolio and 
arranged in order there, whereas in a book it is virtually 


impossible to maintain a proper sequence. A water-colour 
sketch, the parts being as nearly as possible the colours of 
life, is the form of sketch most likely to produce permanent 
satisfaction, but where this is impossible a mapping-pen and 
Indian ink should be used in preference to pencil; pencil 
drawings on loose sheets being very apt to get blurred. 
Annotate your drawings fully at the time that they are 
made, and mark carefully those points about which you are 
uncertain; in time light will probably dawn. In addition 
to the careful drawings of the whole animal, a few entirely 
diagrammatic sketches of the separate parts should be 

As to the points disclosed by your examination, a Nereis 
is a ringed worm (Annelid), composed of a series of rings or 
segments, each of which is of similar structure. You may 
compare it roughly to a railway train, composed of numerous 
similar carriages linked together. Consider for a moment 
the railway train as the more familiar object. Its form is 
obviously an adaptation, as the biologist calls it, to its 
particular form of movement. As it sweeps gracefully 
round a curve, you see at once how necessary and suitable 
its form is, how much the freedom of movement depends 
upon the yielding linkage. Almost all animals which can 
move rapidly and gracefully in water, and are of elongated 
shape, are similarly composed of a series of units. In the 
language of Biology they are segmented animals, and Nereis 
and its allies illustrate one of the simplest forms of seg- 
mentation. A simple form because the component units 
are similar throughout the body, only the anterior and 
posterior ends showing slight structural differences. With 
Nereis should be compared, on the one hand, the Nematodes, 
with their unsegmented bodies and peculiarly stiff method 
of locomotion, and, on the other, the more differentiated, 
segmented animals, such as crab and crayfish, where the 
body-units are no longer all similar, but are adapted to serve 
different functions. 

Let us now examine the segments in detail. Any of 
those from the median part of the body, taken at random, 
will show the following points : first, the characteristic 
shape, rounded above and flattened beneath with a central 
groove ; then the appendages, large lateral outgrowths, form- 


ing the parapodia, or "feet." Of these each segment bears 
a pair, and their structure is somewhat complicated (see Fig. 

29). Each consists of a dorsal 
and ventral process, both bear- 
ing tufts of stiff bristles. More 
careful examination by means 
of a lens will show in addition 
the following points. Both 
dorsal and ventral processes 
t, or parapodium, of are Globed, and it is the lower 

Nereis pelagica. d, dorsal cirrus ; lobe of the dorsal and the Upper 

WiS\WS*S: ^be of the ventral only which 
relative lengths of the d.fferent bear bristles, the other two 

parts, and especially the long , , IT, 

dorsal cirrus, are distinguishing lobes are mere vascular plates. 

Ehters. f the Spedes ' After Further, both processes give off 
slender sensitive outgrowths, 

the feelers, or cirri, of which one is dorsal and the other 
ventral. The bristles have usually a peculiar golden sheen, 
and in each tuft there is one of needle-like shape which 
only projects very slightly, but which is easily found on 
dissection. It is to these needles that the muscles are 
attached, and they form, as it were, the skeleton of the foot. 
To recapitulate, the parapodia are hollow, muscular out- 
growths of the lateral body- wall; they are divided into 
bilobed dorsal and ventral processes, each bearing bristles, 
each giving off a delicate sensitive cirrus. By virtue of 
their muscles and bristles the parapodia are locomotor 
organs ; by virtue of their contained blood-vessels they are 
respiratory organs; by virtue of their sensitive cirri they 
are sense-organs. As one or other of these three functions 
predominates in the bristle-worms, we have a corresponding 
variation in the structure of the foot. 

If we look now at the anterior region or head, we find 
that it differs considerably from the other parts of the body. 
Overhanging the mouth is a dorsal lobe which bears eyes 
and tactile processes, and is the head proper. The lobe is 
called the prostomium, and is probably not equivalent to 
a segment. Surrounding the mouth is the peristomium, or 
first true segment, which also bears tactile processes, but 
has no parapodia nor bristles. In most bristle-worms the 
head region consists of these two parts, but in a few, other 



Fig. 30). 

modified segments are added to it. This is interesting, because 
when we pass to Arthropods we shall find that the head con- 
sists of a number of segments all firmly welded together. 

The head of Nereis varies considerably in appearance, 
according to the condition of the parts, whether fully pro- 
truded or retracted. If a large Nereis be killed suddenly, 
as by immersion in spirits, it will be observed to rapidly 
protrude a large "proboscis" or "introvert," which when 
completely everted shows at its tip a pair of powerful horny 
jaws (see Fig. 30). The method of eversion is interesting, 
and is one which is common among Invertebrates. It is 
best understood by taking a glove, fastening two pieces of 
thread about an inch from the tip of one of the fingers 
to represent the jaws, and then doubling in the finger into 
the glove as far as it will go (see the upper diagram in 
The hole left where the finger is doubled in 
represents the mouth of the 
worm, and it will be seen that 
the little tags representing the 
jaws (j in Fig. 30) now lie well 
within the mouth-cavity (m in 
Fig. 30) ; they are not visible 
in the worm under ordinary 
conditions. Now carefully 
double the inturned glove finger 
outwards until the "jaws" lie 
just at the tip of the part 
turned out; this represents the 
"proboscis" of Nereis when 
fully everted, and then bearing 
the jaws at its tip. All the 
part which can be thus everted 
is called the buccal cavity. It 
opens into the pharynx (p in 
Fig. 30), the next part of the alimentary canal, which is 
represented by the remainder of the glove finger, but 
which differs from it inasmuch as it cannot be everted, or 
turned outwards, but can merely be protruded with its 
terminal jaws. The head, therefore, of Nereis appears 
entirely different according to whether the buccal region is 
retracted or everted. In the former condition the mouth 

FIG. 30. Diagrams showing the 
way in which the proboscis is 
everted and retracted in Nereis, 
The upper figure (^4) shows the 
retracted condition, the lower 
(Z>) the everted. For letters see 
text. After Lang. 


appears as a wide opening beneath an overhanging lobe, 
and some little distance from the anterior end of the body. 
In the second condition it appears at the end of the everted 
proboscis, bounded by the great jaws, and opening directly 
into the protruded pharynx, the proboscis itself being 
merely the anterior part of the alimentary canal in an 
everted condition. The actual appearance of the everted 
proboscis with its small teeth is shown in Fig. 35. 

We may now pass on to consider the appearance of the 
head proper. In the living animal, or in the dead animal 
with retracted proboscis, the mouth is seen to be ventral 
and overhung by the prostomium. On its dorsal surface 
the prostomium bears two pairs of eyes, and in addition 
a pair of very small tentacles and a pair of distinct large 
processes called the palps (see Fig. 28). The next ring, 
the peristomium, bears, as we have seen, no parapodia, but 
only four pairs of long feelers or tentacular cirri, which are 
used like the feelers of an insect. 

Behind this head region the segments are all uniform and 
similar except the last, which is without parapodia, but 
bears a single pair of long tactile cirri, or feelers. 

Having made out these points in the external anatomy of 
a typical Chaetopod like Nereis, the next point is to get 
some notion of the internal anatomy. This may be done 
by proceeding at once to dissect Nereis; but unless some 
experience has already been acquired, it will probably be 
found easier to begin with the fisherman's lob- worm (Arenicola 
piscatorum), which can readily be obtained of large size, 
and which is exceedingly easy to dissect. 

The lob-worm is abundant on most sandy shores, especially 
in sand which contains a considerable amount of organic 
matter. It is a sedentary worm, burrowing in the sand, 
and lining the burrow with an organic secretion, which 
gives the walls a certain amount of firmness and renders 
them easily visible when the sand is turned up. It swallows 
the sand for the sake of its organic particles, and rejects 
the indigestible residue in the form of the familiar sandy 
"castings." If these be pushed away the mouth of the 
burrow can be seen, and the burrow itself may be followed 
some distance by digging in the sand. 

For the purpose of examination and dissection the lob- 


worm may be obtained by digging in the sand where the 
castings are abundant. Except by the intervention of a 
strong arm and a powerful spade, however, the process is 
not very easy, and the simplest plan is usually to invoke 
the aid of a fisherman amateur or professional. The speci- 
mens chosen should be not less than seven or eight inches 
in length, and should be obtained uninjured and in the 
living condition. The worms have an exceedingly well- 
developed blood-system, and are full of blood, a fact which, 
combined with the delicate body-wall, makes it not very 
easy to obtain perfectly uninjured specimens. 

The lob-worm will not be found easy to keep alive for 
any length of time, but it will live for a day or two if 
placed in a vessel with wet sand, and there some of its 
habits can be readily observed. The way in which it moves 
is especially interesting, but before describing this we must 
just glance at its external characters (see Fig. 10). 

In studying these we are at once struck by the marked 
contrast with Nereis, especially in the condition of the 
parapodia. Let us recall for a mome*nt the functions of 
these structures in Nereis; they are locomotor, respiratory, 
sensitive. Now the lob-worm is more or less sedentary, so 
that we should expect that the parapodia, in so far as they 
are locomotor organs, will show reduction. Correlated with 
the sedentary habit we have here, as always, a greater 
difficulty in breathing, and so we have the development of 
special respiratory organs, the gills. Again, a sedentary 
animal has a more limited environment than an active one, 
and is less likely to have well-developed sense-organs, so 
that we should expect to find that the parapodia have to a 
large extent lost their sensitive nature. The first glance at 
Arenicola will show that with loss of function there is also 
degeneration of structure. Its parapodia are mere rudiments, 
little tufts of bristles. The characteristic sensitive cirri of 
Nereis seem to be absent, we say seem to be advisedly, for 
the tuft-like gills in the middle region of the body are in 
reality the metamorphosed dorsal cirri, which have lost their 
sensitive and taken on a respiratory function. With the 
exception of these gills, in reality a specialised portion of 
the parapodia, the parapodia of Arenicola are very greatly 
reduced, and do not function as locomotor organs. 


Having noticed these points, study the movements of the 
living worm. The body is divided into three regions an 
anterior, usually much swollen, region, with lateral tufts of 
bristles; a median region, with the conspicuous gills and 
less obvious bristles ; and a tail region, with neither bristles 
nor gills. As it is thus destitute of definite locomotor 
organs, our first query must be, How does Arenicola move 1 
If you watch your specimens closely, you will be struck by 
a marked and peculiar wave of motion which begins in the 
gill region, and gradually sweeps forward to the anterior 
end. This wave produces a very marked distension of the 
body, and has all the appearance of being due to the passage 
forward of fluid within the body-cavity. The distension is 
most marked in the anterior region, and often terminates in 
the protrusion at the extreme anterior end of a " proboscis," 
with numerous papilla on its surface, which is obviously 
homologous with the "introvert" of Nereis. As the wave 
sweeps forward it will be noticed that the little tufts of 
bristles are completely withdrawn into the body, which 
must greatly diminish the resistance to the passage through 
the sand. As the wave passes any particular spot, it will be 
further observed that, immediately after its passage, the 
bristles are protruded to their fullest extent. When the 
worm is lying on a smooth surface the forward wave is 
followed by a backward one, during the course of which the 
animal slips slightly backwards. There can be little doubt, 
however, that under ordinary conditions the protrusion of 
the bristles must prevent this, for they will tend to grip the 
sides of the burrow. The lob-worm thus works its way 
through the sand as the earthworm does through the earth, 
and in both cases the bristles are of great importance. The 
process is a very interesting one, and can be readily watched 
in a living Arenicola lying on wet sand. 

The lob-worm, indeed, is of interest in several respects, 
for it seems to stand half way between the active worms 
like Nereis, and the very passive tube-forming types like 
Terebella and Serpula. At one time the PolychaBtes were 
divided into two sets the sedentary tube-builders, and the 
active free-living forms. This classification is no longer in 
use, for it is found that many forms not nearly related have 
independently taken to a sedentary life. Nevertheless, it 


had a superficial justification in the fact that sedentary 
forms have certain external characters in common. In 
Arenicola we see, as it were, the first effects of the passive 
life upon the organism. As the sedentary habit becomes 
more firmly fixed, the bristles become more degenerate, 
except when specialised anteriorly to aid in tube-building. 
At the same time the tube becomes more and more highly 
developed. It may consist entirely of secretion poured out 
by the animal, or may be composed of foreign particles glued 
together by the secretion. This secretion is present to a 
slight extent in Arenicola^ where, as we have seen, it gives 
a certain amount of firmness to the walls of the burrow. 
In most tube-builders there are on the ventral surface 
swollen areas, known as "gland-shields," which seem to be 
of much importance in tube-formation. Though these as 
such are not distinct in Arenicola, yet the ventral surfaces 
of the segment lines in the middle region of the body are 
in life much swollen, and are probably of much importance 
in the production of the secretion used in lining the burrow. 

In looking for these glandular regions it will be noticed 
that in Arenicola the body is closely ringed, the rings being 
more numerous than the bristles which mark the segments. 

Having observed these points, the next step is to dissect 
the internal organs. Pin the animal down on wood or 
paraffin under water, with the dorsal surface that bearing 
the gills uppermost. An ordinary pie-dish, in which a piece 
of weighted cork or wood has been placed, makes an excellent 
dissecting-dish, or a couple of candles may be melted in the 
pie-dish, and the animal pinned down on the solidified 
surface. Put the anterior pin in carefully, so as not to 
injure any of the internal structures. Then take a pair of 
fine scissors, and slit up the dorsal surface between the gills 
from the head to a little behind the last gill. Pin out the 
body-walls, and the dissection should present the appearance 
shown in the figure. 

The first point to be noticed is the large size of the body- 
cavity, and the absence of transverse partitions, or septa. 
The large body-cavity is characteristic of bristle-worms in 
general, but in most of them it is divided into numerous 
compartments by divisions which correspond to the segments. 
The absence of these septa is no doubt an adaptation to the 



burrowing habit, for it enables the body fluid to move freely, 
and, as we have seen, that has an important bearing in 
relation to the method of movement. The absence of septa 

is further correlated with 
the power of distending the 
anterior part of the body, 
which has an important me- 
chanical effect in burrowing. 
Running down the centre 
of the body is the alimentary 
canal (al in Fig. 31), which 
in most bristle - worms per- 
forates the septa, but which 
is here almost free in the 
body- cavity. Not entirely, 
however, for in the anterior 
region there are three sup- 
porting mesenteries (s' } s", 
s'"), and behind the gill- 
bearing region there are many 
of these. The anterior mesen- 
tery, or diaphragm, is a struc- 
ture of great interest. It is 
completely circular, and is 
attached to the alimentary 
canal at the point where the 
protrusible region, or buccal 
cavity, opens into the next 
region. During the burrow- 
ing movements the body fluid 
sweeps forward until it is 
stopped anteriorly by this 
circular diaphragm. It then 
exerts a pressure upon the 
diaphragm to which the latter 
can yield in one way only 
by the protrusion of the in- 
trovert, which is doubled 
FIG. 31. -Dissection of lob-worm from dor- outwards by the pressure of 

sal surface. For explanation, see text, the fluid behind. When the 
In part after Gamble and Ash worth. , 

wave sweeps backwards again 



the introvert is retracted, but carries with it a certain amount 
of sand, which, be it remembered, contains the animal's food. 
The process of burrowing is thus aided by the removal of part 
of the sand, while the power of distending the body, espe- 
cially in the anterior region, facilitates the progress of the 
animal. This power is associated with the absence of septa, 
and we thus see how deeply habit affects structure, and 
therefore how it is that the sedentary forms show such an 
apparently close relation to one another. It is one of the 
most difficult tasks of philosophical zoology to distinguish 
between resemblances in animals which are due merely to 
adaptation to a similar mode of life and those which are due 
to common descent. 

As to the other structural peculiarities of Arenicola, 
notice the large glands (gl) opening into the intestine, the 
abundant blood-supply to the gills, the ventral nerve-cord 
(n), seen by pushing aside the alimentary canal, and the six 
pairs of kidney tubules, or nephridia (ne), in the anterior 
segments, which open from the body-cavity to the exterior. 

Into the minute points of structure we cannot enter here, 
but may briefly summarise the salient features of the in- 
ternal anatomy of a Polychsete worm. All have "a large 
body-cavity, or space between alimentary canal and body- 
wall, and this is usually divided into chambers by cross 
partitions. The alimentary canal runs straight down the 
body, and has anterior and posterior openings (contrast sea- 
anemones and their allies). There is a ventral nerve-cord, 
and typically a pair of kidney tubes to each segment, but 
these are often reduced in number. 

In classifying worms the most important points to be 
noticed are the shape of the head and the nature of the 
feet, or parapodia, and the bristles. Our British Polychsetes 
are very numerous, so that we can select only a certain 
number. Those selected are those which are fairly common 
at most parts of our coasts, and are of sufficient size to be 
examined and identified with a lens or simple microscope. 
The more minute forms, though often of great interest, are 
beyond our scope. Even with this limitation, however, 
the worms form a difficult group, and their recognition can 
never be made easy ; but their diversity of habitat renders 
them a group of extraordinary interest. Many of them are 


exceedingly beautiful both in form and colour, and the 
habits of the tube-builders make them very interesting pets. 
Although all are furnished with bristles, which are often 
large and strong, yet most are greatly relished as food by 
the carnivorous inhabitants of the ocean. This fact every 
fisherman knows, and the voracity with which many fish 
will take a worm bait explains clearly enough why it is 
that the worms should display so much ingenuity in seeking 
shelter. Often this shelter is of their own making, as 
witness the great variety of tubes, from the simple jelly 
envelope of Siphonostoma to the elegant sand tubes of 
Pectinaria, and the limy coils of Serpula. Other worms, 
like Nereis itself, form irregular burrows of sand and weed ; 
or seek shelter in rock crevices, roots of weed, and empty 
shells ; or bury themselves deeply in mud and sand. One 
species of Nereis lives inside shells inhabited by the large 
hermit-crab, and thus probably gets not only shelter but 
scraps of its host's food. In what respect the hermit is the 
gainer is less clear. Some other forms live among the 
prickly spines of sea-urchins and starfishes, in this way no 
doubt obtaining protection from soft -skinned foes. So 
varied are the habitats of the worms that to the question, 
Where should one look for them 1 ? the answer may be, 
Almost anywhere. In sand and mud, under stones and 
overhanging rocks, among seaweed, wherever shelter and 
food are to be obtained, the worms may be found. At the 
end of this and the following chapters will be found tables 
designed to aid the beginner in naming the common shore 
worms, but many are not easy to identify. 

The first example is one which is, practically speaking, 
common everywhere on the shore. On lifting up stones 
on the shore rocks you are certain sooner or later to uncover 
a little creature about one to two inches in length, which in 
general appearance is very like a " slater," but which when 
disturbed wriggles away with a lateral movement of the 
body which is quite characteristic. It is not very worm- 
like in appearance, for the rings of the body are covered 
by flat plates, or elytra, but the bristles which project at the 
sides of the body quite clearly indicate its real nature. An 
animal displaying these characters is tolerably certain to be 
a species of Polynoe, and the commonest species on the 


shore is generally Pulynoe imbricata, the common scale- 
worm. If you drop your specimen into a collecting jar you 
will notice that it wriggles its way downwards through the 
water, after a fashion which can hardly be justly described 
as swimming. If you go on with your collecting and re- 
examine the worm after an interval, you will probably find 
that the jar contains, in addition to the worm, a number of 
small flat plates of greyish tint. These are the elytra, or 
scales, of the worm, and it not infrequently happens that 
the little creature will throw off every one of these within 
a very short period of its capture. When these are gone 
the segmentation of the body is very clearly visible, and 
the animal looks so different that it may not be recognised 
as the same creature. Not a few of the shore animals have 
this power of throwing off parts of their body, apparently 
on very slight provocation, and in cases like the present the 
use of the habit is not very obvious. 

The Polynoids do not make satisfactory inhabitants of an 
aquarium, nor do they generally make good preparations, 
for it is very difficult to get a complete specimen. Never- 
theless, a few specimens should be taken, for the animal 
well repays examination. It is a very abundant and widely 
distributed species, occurring on both sides of the Atlantic 
and in Japan. It must, therefore, be very well adapted to 
the conditions of shore life, though it is not easy to point 
out the nature of the adaptations. 

The following general points should be made out. The 
body is short, flattened, and has nearly parallel sides. 
The head has three tentacles and a pair of palps, while 
the next segment, the peristomium, bears a pair of elongated 
cirri at each side. The remaining segments are furnished 
with parapodia of typical form, with dorsal and ventral 
branches bearing bristles. Now it will be recollected that 
in Nereis the parapodia bear dorsal and ventral tactile 
processes or cirri. What about the cirri of Polynoe? A 
little careful examination will show you that the ventral 
cirri are present on all segments, though except in the case 
of the anterior segments they are short. The dorsal cirri 
occur in the typical condition on every second segment in 
the anterior segments, and in the posterior region are missing 
only from every third segment. When they are absent 


elytra, or scales, are present, and these elytra are un- 
doubtedly nothing but metamorphosed dorsal cirri. We 
thus see that though Polynoe has so little apparent resem- 
blance to a " worm," yet it is in all essentials of structure 
similar to Nereis. It is a great part of the interest of 
worms that they show in this way how structures may be 
modified and metamorphosed to fulfil different functions, 
and satisfy changed needs. The elytra are hardened, horny 
structures, and must serve to protect the organism, while 
they are said also to be sensitive like the unmodified cirri. 
We shall not consider the structure of Polynoe in further 
detail, but may just notice that like Nereis it has a pro- 
trusible introvert, in this case furnished with two pairs of 
horny jaws. 

Related to Polynoe is the sea-mouse, a much larger and 
handsomer form, which does not occur on the shore rocks, 
but is often thrown up after severe storms. In shape it is 
even less worm-like than Polynoe, for it has an oval- 
depressed body with little sign of segmentation visible 
externally. Either because of its beauty, or because it 
may be practically supposed to be born of the foaming 
breakers which toss it on the beach, it is named after 
the fair goddess who* rose from the waves, and is called 
Aphrodite aculeata. The body is densely covered with 
bristles and hairs, which form a dense felt over the 
scales, and at the sides of the body gleam with brilliant 
iridescence, changing with every changing ray of light. The 
sea-mouse may reach a length of six inches, but is usually 
considerably smaller. The peristomium is remarkable 
because it has shifted in front of the mouth, and bears 
two typical parapodia a very unusual condition. The 
scales number fifteen pairs, as in Polynoe imbricata, and 
are similarly arranged, but they are not visible until the 
dorsal mass of hairs is removed. The sea-mouse is a very 
interesting worm, for it combines wonderful beauty of 
colouring with ugliness of form. It is generally found 
among weed and rubbish on the shore, and as one turns 
over the debris its brilliant hues suddenly flash out in all 
the colours of the rainbow. Partly, as I think, because of 
the unexpectedness of the colouring, partly because many 
people have little appreciation of form in the lower animals, 


Aphrodite has always had abundant praise lavished on its 
beauty. Many people even go so far as to call it the most 
beautiful of the PolychsBtes. There is certainly no doubt 
as to the beauty of colouring, but for my own part I must 
confess to a preference for some of the leaf-worms, which 
present a combination of beauties of form, colour, and 
motion which is denied to Aphrodite. 

As to the habits there is not much to be said, for the 
worm lives in mud or sand in deep water, and is not easy 
to keep alive. Although it might be supposed that the 
thick coating of bristles would render it anything but a 
pleasant mouthful, it is nevertheless greatly relished by the 
cod and other fish, whose stomachs are sometimes filled with 
fine specimens. 

There is another common shore worm which is related 
both to Polynoe and Aphrodite, but differs markedly in 

FIG. 32. Sthenelais boa. After Johnston. 

appearance from both. This is the common sand Polynoid, 
Sthenelais boa (see Fig. 32), which lives in sand or sandy 
places. It resembles Polynoe and the sea-mouse in having 
the dorsal surface covered with scales, but differs very 
markedly from both in its elongated shape and numerous 
segments. Specimens reaching a length of eight inches are 
said to sometimes occur, but the usual length is from five to 
six. The body is flat, narrow in proportion to its length, 
and hardly tapers at either end, so that the worm looks as 
if it had been abruptly truncated in front and behind. 
Though the colours are unobtrusive quiet sandy greys or 
browns yet the size and shape give the worm much greater 
beauty of form than that displayed by the ordinary squat 
Polynoids. It is common in most places where there is 



sand, and may be obtained either by digging in the sand, 
or, quite as frequently, under stones which are resting on a 
bed of muddy sand. It does not throw off the elytra quite 
as readily as the common Polynoe, but has almost a worse 
fault in the tendency to break into pieces on very slight 
provocation. It has, on the other hand, the great advantage 
of preserving well, and making a beautiful preparation when 
once it can be obtained intact. 

Some interesting points of structure may be noticed. 
The scales begin on the second segment, and up to the 
twenty-sixth segment occur on alternate segments; after 
this they are borne on every segment. In addition each 
segment bears two small gills which are covered by the 
scales. These gills are believed not to be homologous with 
dorsal cirri, which are here represented only by the scales. 
The last segment of the body bears two extremely fragile 
cirri. The worm is sometimes called "brown cat" by 
fishermen, who call another sand worm (Nephthys) " white 
cat." There is some superficial resemblance between the 
two, but the "white cat" has no scales, and is much more 
rapid in its movements. 

The next family we shall consider is that of the "leaf- 
worms" (Phyllodocida?.). The family includes some of the 
most beautiful of worms, remarkable alike for beauty of 
form, of movement, and of colour. They owe their name 
and much of their beauty to the fact that their cirri are 
converted into leaf-like plates which are used in swimming. 
These leafy plates are often brightly coloured, green tints 
predominating in their colouring, and they stand out like 
oars at the sides of the body. When the animals move a 
wave of motion sweeps down the long rows of oars, while 
at the same time the long lithe body sways from side to 
side. If we add that some forms possess a lovely changing 
p>ieen, in addition to the bright colour seen in repose, it is 
easy to understand that the Phyllodocids are often beautiful 

It is interesting to note some of the differences between 
their leafy plates and the scales of Polynoids. In the latter 
the scales are attached by a small area usually near the 
centre, so that the whole series forms an armature of 
overlapping scales, the elements of which are capable of 




relatively little movement. In the leaf-worms the plates 

are attached by one end only, so as to be freely movable. 

Both the dorsal and ventral cirri are modified to form these 

plates, but the dorsal are the larger. 

Besides serving as locomotor organs, the 

cirri have another function. When the 

worms are irritated or attacked, they 

pour out an abundant jelly-like secretion, 

which examination shows to be produced 

by glands on the plates. It is probable 

that this mucus protects them from some 

enemies. It is poured out in special 

abundance when one employs any of the 

ordinary reagents to kill the worms, and 

in consequence spoils them very much as 

specimens. Inrsome species the plates fall 

off almost as readily as do the scales of 


Of the type genus Phyllodoce we shall 
consider two species only, which differ 
from one another in appearance very 
markedly. These are the small brown 
Phyllodoce maculata, and the large green 
P. lamelligera. The former, or spotted 
leaf-worm, occurs freely among the shore 
rocks, especially among sand. It reaches 
a length of from three to four inches, but 
is very slender in proportion to its length, 
a worm of about three and a half inches 
long being not more than about one-tenth 
of an inch broad. It is an active little 
creature, wriggling over the surface of the 
sand, or swimming through the water 
with all its plates in active movement. 
The colour is not unlike that of sand, 
being a pale brown with three very dis- 
tinct dark brown spots on each ring. As in all species of 
Phyllodoce^ the head (see Fig. 34) bears four small tentacles 
near its anterior end, and a pair of distinct dark eyes near 
its posterior margin. Behind the head proper are three 
segments more or less fused, and bearing in all four pairs 

or Phyllodoce lamel- 



FIG. 34. Head and intro- 

of tentacular cirri. The remaining segments bear parapodia 
consisting of a single branch, with leaf-like ventral and 
dorsal cirri. The bristles are relatively 
few in number. In living specimens 
you will notice the frequent eversion of 
the capacious proboscis, or introvert, 
which has no jaws, but bears small pa- 
pillae. This is an extremely common 
worm, and one almost certain to be en- 
countered. Though the colouring is 
sober, it is a pretty little creature, and 
repays careful examination. 

The other species mentioned, the 
paddle -worm (P. lamelligera), is very 
much larger, and is one of the hand- 
somest of our British wDrrns (see Fig. 
33). It has been known to reach a 
vert (i) of Phyiiodoce length of two feet, but is more usually 

lamelhgera. After Ehlers. , . , ' . 1,1 

twelve inches or under. It is a bulky 
worm with a flattened body, usually about a quarter of an 
inch wide, and is green in colour with iridescent metallic 
tints. It lives beneath stones near low-tide mark, and in 
many places is not uncommon. Like the preceding species, 
it has a capacious introvert furnished with papillae, but with- 
out jaws. The number of tentacles and cirri is the same as 
in the preceding species, but it differs from this in the shape 
and position of the dorsal plates. There can, however, be 
no possibility of confusion between the two species, for their 
general appearance is very different. 

We shall not consider any other species of Phyllodoce, 
although others do occur on our shores, but may just notice 
some points as to the genus as a whole. It is a large genus, 
and is, indeed, by some authorities split up into sub-genera 
denned by the characters of the head, but the specific 
characters are often very indistinctly marked. In Poly- 
chsetes in general the characters relied on in discriminating 
species are usually the numbers and characters of the 
bristles, the characters of the parapodia, and the structure of 
the head and introvert when this is present. But in the 
genus Phyllodoce, while some of these points display great 
constancy, others seem to display much individual varia- 


bility. Thus, to take one example only, it is believed by 
some authorities that there are two "paddle-worms," one 
called P. lamelligera and the other P. laminosa, while 
others maintain that these two are one, or are mere varieties 
of one species. The curious point is that those who regard 
them as distinct are by no means agreed as to the dis- 
tinguishing features of each, a fact which certainly suggests 
the occurrence of variation. Other authorities believe that 
very many of the so-called " species " of Phyllodoce are mere 
varieties, and that one may, as it were, pick out a few 
dominant types, round each of which a number of more or 
less clearly defined varieties group themselves. The point 
is a very interesting one. 

The next genus Eulalia differs from Phyllodoce in the 
presence of an additional tentacle, so that the head bears 
five instead of four of these. Curiously enough, however, 
apart from this prime difference, there is an extraordinary 
parallelism between the " species " of Eulalia and the 
"species" of Phyllodoce. Thus there is a species of Eulalia 
which, except for its tentacle, resembles in almost every 
respect Phyllodoce maculata, while our commonest Eulalia 
(E. viridis) has a twin brother in a green Phyllodoce. As 
the extra tentacle in Eulalia is often by no means easy to 
see, there is no difficulty in understanding that this fact has 
tended to add greatly to the confusion of nomenclature and 
description, so that the Phyllodocids in general form a very 
difficult family, and one in which there is still much to be 

We shall only describe one species of Eulalia, and that is 
the common and beautiful E. riridis, the green leaf-worm. 
It is a small w T orm, three inches or less in length, of a bright 
green colour, which is peculiarly vivid in females filled with 
eggs. It is common in rock crevices at many parts of the 
coast, and is readily recognised at a glance as a Phyllodocid 
from the green leafy plates which in life are in constant 
movement. The fact that it is a conspicuous worm and 
lives considerably above low-tide mark makes it the most 
obvious of the Phyllodocids, for P. lamelligera is local and 
P. maculata is so slender and inconspicuous as to be readily 
passed over without notice. In spite of its beauty and 
fragile appearance, Eulalia, like the other Phyllodocids, is a 


carnivorous animal, living chiefly upon other bristle-worms. 
It is also of interest because of the beauty of the egg masses 
which are laid in spring. Everyone must have noticed the 
little sacs of transparent jelly, filled with minute bright 
green eggs, which are so common in spring on the shore 
attached to stones, shells, and weed. In shape they are like 
very large grapes with a soft jelly stalk. These are the eggs 
of Eulalia viridis, and if you pierce the jelly and examine a 
few of the freed green specks under the microscope in 
water, you will probably see the little top-shaped larvae 
creating miniature whirlpools by the active movements of 
their long cilia. These peculiar larvae occur in the life- 
history of most bristle-worms, and also of Molluscs. They 
are active little creatures adapted for life near the surface of 
the water, and thus are probably important in the distribu- 
tion of sedentary forms like most of the bristle-worms. At 
least the early stages of development can be followed in the 
eggs of the Phyllodocids, and their egg packets are certainly 
the most conspicuous and the most readily found of the eggs 
of Polycheetes. 

It is, perhaps, hardly necessary to describe Eulalia viridis 
in further detail. The fifth tentacle arises far back on the 
head, between the two eyes, and as in Phyllodoce there are 
four pairs of tentacular cirri, or tactile processes, on the 
head. The dorsal plates are pointed and elongated, and the 
ventral similar but smaller. The bright green colour is 
very characteristic, and makes the worm easy to recognise. 

Class. CHJETOPODA (bristle-worms). 
Order. POLYCHJSTA. The bristle-worms of the sea. 

Body short, flattened, 
with parallel sides 

Body oval and de- 

Worms with flat scales, 

or elytra, on their \ Fain. Aphroditidte. 

pressed, covered dor- 
sally with a felt of 
bristles Aphrodite. 

Body elongated and 
worm - like. Head 
with three tentacles 


Worms with leafy plates ^l ( Head with four ten ' 

taeles - I tacles Eulalia. 

Fam. Aphroditidse. 

Polynoe. P. imbricata has fifteen pairs of scales, which fall off very 
readily. The projecting bristles have a length equal to half 
the width of the body. 

Aphrodite. A. aculeata has fifteen pairs of scales beneath the felt 
of bristles. There is a small median tentacle and two long 
palps on the head. The body tapers posteriorly. 

Sihenelais. In S. boa the head has three tentacles, a pair of long 
palps, and four eyes. The first segment bears three pairs of 

Fam. Phyllodocidse. 

Phyllodoce. In P. maculata the body is very slender, the dorsal 
plates are rounded. In P. lamelligera the body is broad and 
massive, and the dorsal plates are oval or heart-shaped. 

Eulalia. In E. viridis the body is bright green, and the dorsal 
plates are narrow and pointed. 

All the worms mentioned in the chapter are widely distributed 
throughout the British area. 


BEISTLE-WORMS continued. 

The Nereids Formation of Heteronerete Characters of Heteronereis 
The common species and their habits Two sand-worms, Neph- 
thys and Glycera Their structure and habits The rag- worms 
The worm Cirratulus The Terebellids and the process of tube- 
building The tube of Pectinaria Trophonia plumosa The 
Sabellids and Serpulids The tube-building of Sabellaria The 
"living film " Ribbon- worms Polyzoa. 

THE family with which this chapter opens is one contain- 
ing a number of large and common forms. It is the 
!N"ereida3, to which the genus Nereis, described in the pre- 
ceding chapter, belongs. As intimated there, by far the 
commonest species, on Northern coasts at least, is Nereis 
pelagica, which occurs abundantly between tide -marks, vary- 
ing in size from two to six or more inches. It is usually of 
a fine bronze colour, and is an active and handsome form, 
showing not a little colour variation. 
As to the species marks, the easiest 
way of recognising it is to examine 
the little teeth, or paragnaths, on 
the introvert see Fig. 35), but it is 
also characterised by the great size 
of the palps, the elongated shape 
of the head, the long dorsal cirri, 
and the arched back. It may be 
well to notice that in Nereis the 
palps are readily distinguished from 
tentacles by their shape and size. 
This is not invariably the case, 
but the two may always be dis- 
tinguished by the fact that while 


a 6 

FIG. 35. Upper (a) and 
under (6) surface of the 
introvert of Nereis pela- 
gica; j, jaws. The dark 
specks are the paragnaths, 
which vary slightly in 
different specimens. After 


the palps arise from the ventral surface, the tentacles are 
dorsal. Perhaps one of the most interesting things about 
this, as about most of the other species of Nereis, is the 
changes which it undergoes at sexual maturity. When hunt- 
ing under stones for specimens you may not infrequently 
find one which is peculiar in that while the anterior part of 
the body has all the usual characters, the posterior region is 
strikingly different in appearance, so that the worm looks as 
though it were compounded of two dissimilar worms. The 
colour is also remarkable, for the body is bright green 
anteriorly, and pure pink in the posterior region. If you 
examine the posterior region more closely, you will find that 
the difference in appearance is largely due to the modifica- 
tion of the parapodia. These have greatly increased in size, 
and their different regions have developed leafy outgrowths, 
which convert the parapodia as a whole into swimming 
organs. The resultant change in the external appearance of 
the animal is so striking that the modified form was for long 
supposed to belong to a distinct genus, and was called 
Heteronereis. It is now known to be merely the mature 
form, and owing to the fact that it is adapted for a free- 
swimming existence no doubt assists in the distribution of 
the species. It will be remembered that in the Coelentera 
the sessile sea-firs bud off active swimming- bells, which 
produce the ova, and by their power of swimming ensure 
the distribution of the species. In certain small worms 
belonging to the genus Syllis and to allied genera something 
quite analogous occurs, for the worms bud off new indi- 
viduals, which are modified for a free-swimming life, and 
which contain the eggs and spermatozoa. In another very 
curious worm, the "Palolo" of Samoa and Fiji, a portion of 
the body becomes modified, much in the same way as in 
Nereis, but the modified portion separates off, and swims 
away, leaving, it would seem, the anterior region behind at 
the bottom. The separated portions of the worm appear at 
the surface of the water in extraordinary numbers at certain 
seasons, and are caught and eaten by the natives. The 
" swarming " only lasts for a short time, and it is probable 
that the worms die after laying their eggs, while the 
"heads," which have remained at the bottom among the 
coral blocks, bud out new bodies, and eventually repeat the 


whole process. In Nereis, though the genital products occur 
only in the posterior region of the body, this part does not 
separate off as in the Palolo. 

In N. pelagica the modifications undergone by the mature 
female are less marked than those in the male. The female 
Heteronereids are very much larger than in the male, and 
have fewer of the segments modified. The modification is 
also less marked. It is not uncommon to find large speci- 
mens with a few merely of the posterior segments under- 
going incipient modification. One striking characteristic of 
both sexes of Heteronereids is the presence of a sensitive 
rosette on the last segment of the body. Further, in the 
male the eye increases in size and becomes beautifully 
coloured, and, as already noticed, the colours in both sexes 
become brighter. These very interesting changes can be 
followed very readily on the shore, especially in the 

Besides N. pelagica, two other species occur free on the 
shore in most places, in addition to N. fucata, a handsome 
species found in shells inhabited by hermit-crabs. The two 
species are N. dumerilii, a rather small form with very long 
cirri, which forms a tolerably firm tube, and N. cultrifera, a 
large form in which the dorsal cirri are short, and the back 
less well arched than in N. pelagica. Both species occur in 
situations somewhat similar to those affected by N. pelagica, 
and will be generally found among gatherings of the latter. 
The distinguishing features are noted at the end of the 
chapter. To get N. fucata, on the other hand, one must 
collect a few large specimens of hermit-crabs, especially 
those which occur in whelk shells, and are, therefore, nearly 
full grown. Such specimens are sometimes flung on the 
beach by storms, and though often dead or moribund, are at 
times living and active. If still alive, put your specimens 
in clean water, and after a time you will not improbably be 
rewarded by seeing the hermit entirely recover his disturbed 
equanimity, and sit, metaphorically speaking, at his ease on 
his doorstep placidly twirling his long feelers. You may 
further see protruded above the hermit's head the long 
feelers and stout palps of a brick-red Nereis. The worm 
does not completely quit the shell, but protrudes the ante- 
rior part of the body, and no doubt shares in any food 


which may be going. When the hermit is alarmed and 
retreats, the worm does the same, and then retires to the 
topmost whorl of the shell, entirely out of sight. So far 
does it retreat that it is by no means easy to extract it from 
a shell quitted by the hermit, and a very vigorous shake is 
required before the attic tenant will show himself. There 
is usually only one worm present, but I have found two in 
one shell. The percentage of cases in which the worm 
occurs also varies greatly according to the locality ; off the 
Isle of Man it is said to be present in 90 per cent, of the 
whelk shells inhabited by the hermit-crab, while in other 
places it is relatively rare. It is not entirely confined to 
hermit-crab shells, but occurs occasionally free, and occa- 
sionally in empty shells. 

The living animal is very easily recognised by its colour 
and markings. It is of a beautiful red tint, with two pure 
white bands on the dorsal surface. After death, however, 
the colouring soon fades, whatever the preservative em- 
ployed. In structure the worm differs from the two 
preceding in that the parapodia are not all similar, the 
posterior differing from the anterior. In the posterior 
segments especially the uppermost lobe of the parapodia is 
elongated, arched, and swollen. It is highly vascular, and 
no doubt functions as an efficient respiratory organ. 

We shall describe only one other species of Nereis, and 
that is the large and handsome Nereis virens. It is a green 
worm, differing from the other species described in the 
presence of large leafy plates in the dorsal region of the 
parapodia. The plates are not expansions of the dorsal 
cirrus, like the plates of Phyllodocids or the scales of 
Polynoids, but are expansions of the dorsal lobe itself (cf. 
N. fucata). The structure of the parapodium altogether 
suggests to some extent the modified parapodia of the 
"Heteronereis" of other species, and it is interesting to note 
that though N". virens does become converted into a Hetero- 
nereis, the changes are relatively slight. The worm reaches 
a length of over a foot (up to eighteen inches), and when 
the large black jaws are fully protruded has quite a formid- 
able appearance. It is said to be called the " Creeper," and 
to be used as bait on some parts of the coast. The leafy 
plates, like those of Phyllodocids, secrete an abundant 


supply of mucus which is here used to line the burrow. 
The worm occurs between tide-marks, and is sometimes to 
be found by digging near the rocks, while at other times it 
may be found swimming freely. It is a somewhat local 
form, but Granton and St. Andrews may be mentioned as 
places where it is to be found. 

It is hardly necessary to enter in detail into the characters 
of the worm ; the size, the colour, and the structure of the 
parapodia render it easily recognised. 

The species of Nereis are very abundant on the shore 
rocks, and are certain to be encountered in shore hunting. 
With the Polynoids and the Phyllodocids they constitute 
the commonest and most highly developed of the large free- 
living worms of the shore. In all three sets the body is 
very uniform in structure throughout its length, the head 
is well furnished with various tactile processes, and the 
parapodia are large and well developed. In studying the 
bristle-worms, therefore, it is well to become familiar with 
the common members of these three families before pro- 
ceeding to the more difficult sedentary forms. Related 
to these three families are two small families of sand- 
inhabiting worms, which have much less conspicuous tactile 
processes on the head, and considerably less brightness of 
tint. These are the Nephthydidse, including Nephthys 
hombergii, the " white cat," and the Glyceridoe, including 
Glycera capitata, both interesting and curious worms. 
Both are genuine burrowers, to be found along with many 
other worms by digging in sand marked by worm -tracks 
and burrows. When turned up by the spade both (Us- 
play active movements, during the course of which the 
enormous introvert is constantly protruded and retracted, 
with a rapidity which is astonishing, and even alarming 
to timid people. The performance suggests a juggler's 
trick, in that the ejected proboscis seems bigger than the 
worm. In both cases the introvert is an important instru- 
ment in burrowing. 

The " white cat " (Nephthys hombergii) is common in the 
sand in most places, and is valued by fishermen as bait. 
The colour is greyish and sandy, but the body displays fine 
opalescent tints. Usually the worm does not reach a length 
of more than three to four inches, and it is remarkable in 



Fio. 36. Foot, or 
parapodium, of 
Nephthys hom- 
bergii. d, dorsal, 
and v, ventral lobes 
of foot with bristles 
and thin plates, p ; 
g, gill ; c, ventral 
cirrus, the dorsal 
is absent. After 

being quadrangular in section. The dorsal surface is flat, 
and so also is the ventral, save that it has 
a very distinct median groove. The foot 
is of remarkable structure (see Fig. 36). 
When fully protruded the introvert is 
seen to be furnished with numerous 
papillae. There are also two jaws, but 
these are small and are not protruded. 
The worm is readily recognised by its 
opalescent colours and its very active 
movements, and is a common form which 
ought to be found and studied. 

While digging for Nephthys one may 
occasionally turn up an elongated worm 
with a body which narrows rapidly in 
the posterior region to form a long tail. 
The colour is pale yellowish, and the 
animal has an eminently characteristic 
habit of coiling itself into a spiral on 
the slightest touch. The head is extra- 
ordinarily long and pointed. An animal 
displaying these characters is a species of Glycera, and the 
commonest species between tide-marks is G. capitata. In 
most species there may be seen on the dorsal region of the 
feet in the living worm, small sac-like gills in which the 
blood corpuscles circulate rapidly, but these are absent in 
G. capitata. The long introvert is crowned by four dark 
jaws, which in the large Glycera of deep water (G. giganted) 
are strong enough to pierce the skin. The different species 
are distinguished by the presence or absence of gills, and 
the minute structure of the parapodia. 

The most interesting point in regard to the habits of 
Glycera is the strange way in which it throws the body 
into a close spiral. Like most sand-inhabiting worms it is 
not easy to keep alive in captivity. 

In the reduction of their tentacles, palps, and cirri, 
Nephthys and Glycera lead up to the next genus we shall 
consider. This is the genus Nerine (rag-worms), which 
includes worms without any trace of palps or tentacles. 
The peristomium bears a single pair of long tentacular cirri, 
the dorsal cirri are converted into gills, and the ventral cirri 


are absent. As compared with any of the preceding worms 
the parapodia are reduced, and only project slightly at the 
sides of the body. Both the common species inhabit muddy 
sand, and both are extraordinarily brittle, breaking into 
pieces on the slightest provocation. Common as the worms 
are it is in consequence very difficult to get a complete 
specimen. The gills (dorsal cirri) are carried curved over 
the back, and being filled with red blood are in life very 
conspicuous objects. The tentacular cirri are broad and 
long, and in life are in constant movement. Like other 
parts of the body these are very apt to be thrown off by 
captive specimens. There is little difficulty in distinguish- 
ing between the two species. The larger, N. coniocephala, 
is said to attain a length of eight inches, but on the 
East Coast at least is usually much smaller; the smaller, 
.ZV. vulgaris, is three to four inches long. The larger is the 
handsomer species, for it is usually of a fine green colour, 
which contrasts with the scarlet gills. In Nerine vulgaris 
the body is usually yellowish red, but also exhibits a ten- 
dency to become green. It will be noticed that the surface 
of the gills is increased by a membrane (the podal mem- 
brane) which extends up the gill, its size differing in the 
two species. The other distinguishing characters are given 
at the end of the chapter. 

In Nerine the parapodia project slightly at the sides of 
the body, but in the remaining worms they are at most 
represented by small tubercles bearing the bristles. The 
worms are almost either burrowers or tube-formers, and 
very frequently the anterior end, which projects from the 
tube or burrow, differs markedly from the posterior. 

The first of these worms which we shall consider is 
recommended by its great abundance on the shore rather 
than by any beauty or great interest. In turning over 
stones on the rocks, the beginner often tries stones firmly 
bedded into mud or sand, and therefore without any under- 
lying cavity. When such stones finally yield to a strong 
pull, they reveal an odorous substratum of mud which is 
usually traversed in all directions by slender scarlet threads 
moving about like living worms. A little investigation will 
show that these are the tentacular filaments and gills of a 
reddish worm embedded in the mud. If molested the 


worm not infrequently throws off these filaments, which 
retain their activity for a long time, and often greatly 
puzzle the beginner. This worm is Cirratulus cirratus, and 
is often exceedingly common in black sand or mud under 
stones. In the early part of the year the worms quit the 
mud, and may be found freely exposed on the rocks in the 
act of spawning. The eggs are of yellowish colour, and as 
in most worms are surrounded by a jelly-like substance. 
As in the case of not a few littoral animals, it is only at 
the breeding season that one is able to get any adequate 
idea of the extraordinary number of individuals which 
occur between tide-marks. In the Firth of Forth in Feb- 
ruary I have seen the rocks literally covered with the 
worms, while at other seasons they can only be found by 
careful search. 

It is not necessary to say much of the characters of the 
worm. The prostomium is long and pointed. Behind it is 
a transverse row of tentacular filaments, which in life are 
distinguished from the gills by their paler colour and their 
"curled" appearance. After death it is not easy to dis- 
tinguish between gills and filaments. The gills are of 
course modified dorsal cirri. They are long, slender, and 
filamentous, and the colour is bright red. They are- most 
numerous and most regularly arranged on the anterior 
segments; but scattered gills occur throughout the greater 
part of its length. Apart from the gills, the parapodia are 
merely represented by papillae at each side of the segments 
bearing small bristles. On the East Coast at least the worm 
does not usually exceed three to four inches in length. 

Much more interesting than Cirratulus are the Terebellids, 
or sand-masons, which build long tubes neatly plastered over 
with particles of sand, shell, and stone. In walking over 
the sand after the tide has ebbed, one very often finds 
great masses of the sandy tubes of these worms. Some of 
these tubes are fringed at the top with branched sandy 
threads, so curious in appearance that the inexperienced 
commonly regard the tube as some kind of an animal. 
These are the empty tubes of TereMla conchilega, the sand- 
mason, and sometimes occur on the shore in extraordinary 
abundance. They are always empty, however, and usually 
not more than a few inches in length. We need not, 


therefore, mourn the untimely decease of innumerable 
worms, for it is only a portion of the house which has 
been sacrificed to the force of the breakers ; and the worms 
are tireless " masons," and can soon repair the damage. To 
find them living we must seek those sandy stretches which 
sometimes occur among the shore rocks. Here we find the 
tubes sticking up vertically from the sand, with their stiff 
fringe and about an inch of tube above the level of the 
sand. It is easy to imitate the action of the breakers and 
pull up the tube ; but the prudent worm has learnt its 
lesson well, promptly retreats to the bottom of its tube, and 
leaves you with a few inches of empty tube in your hand. 
The worms often measure as much as ten inches in length, 
and the tubes are always longer, often much longer, than the 
worm. It is in consequence a somewhat difficult process 
to obtain a complete specimen, especially when we add to 
the other difficulties the fact that the worms are exceedingly 
fragile, and often rupture at a touch. One habit, however, 
aids the process of extrication. The worms show a marked 
preference for rock crevices, and in jointed rocks often 
occupy the widest of the joints. Such jointed rocks are 
often easily split into blocks, and in this way, with the help 
of a geological hammer, it is sometimes possible to get very 
fine specimens. There are a considerable number of Tere- 
bellids to be found on the shore rocks, and many of these 
do not burrow so deeply as Terebella conchilega, and may 
be more easily obtained, but we shall confine our description 
to this handsome species. 

Let us suppose, then, that your excavations have been 
crowned with success, and an intact specimen of the desired 
worm lies before you (see Fig. 37). The colour varies, but 
is often a beautiful rosy tint, the tufted gills being a bright 
scarlet. The head bears numerous long tenta:ular filaments 
like those of Cirratulus, which in life are protruded from 
the opening of the tube. They collect the sand grains and 
other particles which when mixed with secretion form the 
tube, and are sheltered and perhaps protected by the stiff 
fringe of the tube. The first segment (peristomium) forms 
a bilobed lower lip which is used as a trowel to plaster 
the tube. As might be expected from the tube-dwelling 
habit the gills are confined to the anterior segments, where 



they can be freely exposed to the purifying action of the 
water. They further differ from those of Cirratulus in 
being branched and comparatively short. Some other 
adaptations to life within a tube are almost equally obvious. 
Thus the parapodia are greatly reduced, and the bristles 
modified so as to suit the needs of a tube -inhabiting 

On the anterior segments, from four to twenty-one, there 
are in all seventeen 
pairs of papillae 
bearing fan -shaped 
tufts of bristles. 
The papillae repre- 
sent the dorsal lobes 
of the parapodia, 
and are absent from 
the narrow posterior 
region of the body; 
they no doubt assist 
the animal in mov- 
ing up and down 
its tube. The ven- 
tral lobes of the 
parapodia are repre- 
sented by elongated 
vascular bands at 
the sides of the 
segments, each of 
which bears from 
eighty to one hun- 
dred mirmtp Viookq FlG - $I.Terebella removed from its tube. Note 

area minute n >OKS. t ^ e long tentacleS) the tufted gills> and the 

Ihese nooks are difference between the anterior and posterior 

modified bristles regions of the body - 

and are present in various forms in the majority of tube- 
inhabiting worms. Very little observation on the rocks 
will acquaint you with the fact that in most cases a 
tube-inhabiting worm can withdraw into its tube on an 
alarm with extraordinary rapidity. In a worm like Terebella 
the process is assisted by many thousands of hooks, each 
bearing secondary teeth. The hooks are very small, and 
can just be made out in a good light with a strong lens. 


Their presence may often be demonstrated even when they 
cannot be seen, by drawing a needle over the hook-bearing 
area, when a slight grating sound will be heard. Unlike 
the dorsal bristles these ventral hooks occur throughout the 
body, except on the extreme anterior segments. In the 
anterior region in the living worm it will be found that 
the ventral surface is very bright red in colour, and glandular 
looking. This is due to the presence of fourteen to twenty 
pairs of " gland-shields," which secrete the mucus which is 
the basis of the tube. 

A considerable number of Terebellids live on the shore, 
differing from one another chiefly in the structure of the 
gills, the number of dorsal lobes, of gland-shields, etc. 
Small specimens of Terebella or of others will live for a 
time in confinement, when the process of tube-building can 
be watched. The worms may sometimes be induced to 
build an incomplete tube along the side of the aquarium, 
so that the worm may be watched through the glass within 
its tube. Like other tube-inhabiting forms, Terebella con- 
cliilega shows considerable power of adapting its "masonry" 
to the special conditions in which it may be placed ; thus 
specimens living in deep water construct tubes which in 
several respects differ from those of shallow-water forms. 

Another interesting tube-worm, smaller and less abundant 
than Terebella, is Peciinaria belgica (see Fig. 38), which is 
to be found in sandy pools. Its tube is short, usually about 
one and a half inches, is without a fringe, but displays a 
neatness of workmanship which makes the tubes of Terebella 
seem coarse and clumsy. It is constructed of sand grains, 
which are all of the same size, and are smoothly and evenly 
worked into a plaster of mucus, so as to form a beautiful 
mosaic. The tube is firm enough not to collapse when the 
tenant is removed, and is open at both ends. The large end 
corresponds to the head of the worm, but it is this end which 
in life is buried in the sand, the narrower posterior end pro- 
jecting from the surface of the sand. The worms live well 
in captivity, and the habits may be readily observed in 
specimens placed in a glass jar with clean water and a layer 
of sand. In such specimens you should see a beautiful 
crown of golden bristles (b in Fig. 38) protruded from 
the large end of the tube, and used as a trowel to excavate 



a hole in the sand. If the burrowing occur near the glass, 

the short tentacles (te) will be seen in addition to the 

golden bristles. When removed from its 

tube, the worm is seen to be short and 

stout, with relatively few segments, and a 

peculiar terminal plate (tp), which serves 

to close the posterior end of the tube. The 

prostomium bears tentacles like those of 

Terelella, and is much less conspicuous 

than the peristomium, which carries the 

bristles, and projects in the form of a 

collar. There are two pairs of gills (g). 

As in TerebeUa, the parapodia (p) are 

represented by dorsal clusters of bristles 

and ventral hooks. The worms do not 

quit their tubes except at the approach 

of death, but are capable of some amount 

,. , ' . r . ,, . , , .., FIG. 38. Pectinarut 

01 locomotion, carrying their tubes With belgica removed from 

them. In Terebella, on the other hand, %**&*% 
the tubes are permanently fixed in one text. After Malm- 

Very different from Terebella or Pectinaria is the fisher- 
man's lob-worm (Arenicola piscatorum), whose appearance 
and habits we have already described. It is abundant in 
most suitable places, except where incessant persecution has 
almost exterminated it, and as bait has, or had, considerable 
importance to fishermen. 

Though we have necessarily omitted many not uncommon 
shore worms, there is one interesting if inconspicuous worm 
which deserves special mention. This is Trophonia plumosa, 
which is found not infrequently in muddy places on the 
shore rocks. It varies in length from two to four inches, 
and is a Northern form, which is both more abundant and 
reaches a greater size in the Northern than in the Southern 
waters of our islands. At first sight it may seem both an 
uninteresting and a puzzling form, for there is almost nothing 
in the external appearance to take hold of. The colour is a 
dull drab, and the only striking character is the great pro- 
jecting sheath of bristles at the anterior end. Nevertheless 
the worm is interesting enough. The head is usually re- 
tracted, but when protruded it is seen to bear two long 


tentacles, pinkish or yellow in colour, and eight short gills 
coloured by the green blood which they contain. The great 
head sheath is formed by the dorsal bristles of the anterior 
segments, but similar though shorter bristles occur on the 
other segments. The ventral parts of the parapodia are 
represented by projections bearing curious hooked bristles 
of remarkable structure. The surface of the skin is 
roughened by numerous papillae, which in an allied form 
(Siphonostoma) secrete a jelly-like investment absent in 
Trophonia. So far as my" experience goes, it is a sluggish 
animal, not displaying much activity of any kind, but 
nevertheless it is zoologically full of interest. 

The next family to be considered is that of the Sabellidae, 
which includes a large number of common and beautiful 
worms. They usually construct tubes of sand or mud, and 
are characterised .by the presence of a " crown " of beautiful 
gill filaments. These are formed by the splitting up of the 
palps, and are of a beautiful green colour owing to the 
contained blood. The base of the crown is concealed by 
the peristomium, which forms a projecting collar. As in 
Terebellids the parapodia are represented by bristles and 
booklets, but the booklets are ventral in the anterior nine 
segments (thorax), and dorsal in the posterior segments 
(abdomen). We cannot describe even the more common 
Sabellids, but may take as an example Dasychone bombyx, 
a worm which is easily recognised by the eyes on its gills. 
It forms a soft mucoid tube impregnated with particles of 
sand or mud, and attached to shells or stones. The worm 
is short (1-1J inches), of a reddish brown colour, and 
furnished with a beautiful crown of light -coloured gill 
filaments. When examined with a lens these filaments are 
seen to bear dark- coloured eyes, arranged in pairs along the 
dorsal surface of each filament. Owing to the presence of 
these eyes the worm is extraordinarily sensitive to varia- 
tions in intensity of light, and disappears into its tube like 
a flash if a shadow falls on it. Like other Sabellids the 
worm, if it can be kept alive, is a most delightful inhabitant 
of an aquarium, where it may be watched protruding its 
lovely crown from the tube, so that all the filaments are 
bathed with water. 

Closely related to the Sabellids are the Serpulids, which 



differ from them in possessing a limy tube which can usually 
be closed by an operculum, and in the presence of the so- 
called " thoracic membrane," which is a delicate membrane 
at either side of the thorax used in smoothing the inside of 
the tube. There are a great number of Serpulids just as 
there are of Sabellids. The conspicuous white limy tubes 
are very common objects on shells and stones, both on the 
rocks and among the wreckage flung on the beach, and are 
familiar to most people, but the worms themselves are less 
well known. In deep water Serpula itself is very common, 
but on the shore 
rocks a form called 
Pomatoceros trique- 
ter is the most fre- 
quent. Notice the 
distinct keel which 
runs along the dorsal 
surface of the tube, 
and ends in a dis- 
tinct spine over- 
hanging its opening; 
then select a few of 
the largest speci- 
mens you can find, 
and place them, 
with the shells or 
stones to which they are attached, in a vessel with clean 
water. After a period of patient waiting you will see a 
crown of brilliant gills protruded, whose white ground colour 
is relieved by splashes of crimson, orange, or blue. As the 
filaments separate out in the water, notice that, as in 
Sabellids, they arise in two clusters. Note further that in 
one of the clusters the filament nearest the mid-dorsal 
line is converted into a stopper, or operculum, borne 
on a stalk. The corresponding filament at the other side is 
aborted. If the worms be not alarmed, they will protrude 
themselves far enough to show a collar like that of a Sabellid, 
and the wavy thoracic membrane. In the thoracic region a 
blue tint usually predominates. By carefully breaking the 
tube it is possible to remove the worm without injury, so as 
to display the whole body. Note then the general resem- 

Fio. 39 Serpula vermicularis within its tube. 
o, operculum ; g, gills ; t, tube. 


blance to a Sabellid, and also the character of the 

Two other common Serpulids may be named without 
description. These are the tiny Spirorbis, which forms its 
coiled white tubes on Fucus, and is often very abundant, 
and Filigrana implexa, a social form whose narrow, inter- 
lacing tubes are often very conspicuous on the shore rocks. 

The last worm we shall describe is Sabellaria alveolata, a 
curious and interesting form often very abundant on the 
shore. It is not closely related to the preceding worms, 
and forms a very firm but irregular sandy tube. These 
hard tubes are sometimes found singly on shells and stones, 
but in places where the worm really flourishes, numbers of 
tubes occur together, so that the worms build up blocks of 
what looks like coarse porous sandstone. These blocks are 
hard, and the worms delicate and fragile, so that it is by no 
means easy to obtain perfect specimens. 

Before examining worms removed from the tubes, watch 
some uninjured specimens within their tubes. They will be 
seen to protrude from the tube a crown of bristles, similar to 
those of Pedinaria but less brilliant, and also numerous 
tentacles. The tubes differ, however, from those of Pectin- 
aria in being quite immovable. 

In the specimens removed from their tubes notice that 
the body is sharply bent, so that the posterior region with 
its terminal aperture lies at the opening of the tube close to 
the mouth. The worms are not more than an inch long, and 
the anterior thickened region is usually of a bright purplish 
tint, while the narrow reflexed posterior region is paler in 
colour. The peristomium has grown right forward over the 
head and bears the prominent bristles. The prostoinium, 
as in Sabellids, bears numerous gill filaments, but in addi- 
tion there are dorsal cirri which act as gills (cf. Terebellids). 
There are many other structural peculiarities too difficult to 
be discussed here, but the hardened masses of tubes, the 
purple colour, and the peculiar shape are so characteristic 
that there is little difficulty in recognising the worm. 

In concluding this survey of the bristle-worms it may be 
well to point out that their great abundance makes it very 
difficult to mention more than a few representative forms. 
They occur everywhere on the rocks, and are adapted for all 


sorts of lives, but as most are relished as food by the larger 
shore animals so most either form tubes or burrows, or seek 
convenient lurking-places. Though some, like the Phyllo- 
docids, can swim with ease, in the general case the bristle- 
worms when they possess any power of locomotion are 
creepers, using their parapodia as feet. The purely seden- 
tary forms live on minute microscopic particles, found in 
water or in sand, but the active jaw-bearing forms are 
carnivorous. In the resting condition the jaws lie far back 
in the buccal cavity, but when in use they, with the buccal 
sac, are rapidly everted, and can be as rapidly withdrawn. 
The beauty of colouring and of form we have already 
frequently emphasised. 

In view of the frequent difficulty of identification a few 
notes on likely habits for the different species may be wel- 
comed. In rock crevices, or under stones which roof in a 
cavity, one may expect the paddle-worm (Phyllodoce lamel- 
Ugera), the green leaf-worm (Eulalia viridis), the creeper 
(Nereis virens), and other species of Nereis (N. pelagica, 
N. cultrifera, etc.). But for these smaller species of Nereis 
the most likely spots are roots of Laminaria, where many 
other worms also occur. Under stones resting on sand one 
finds species of Polynoe, Phyllodoce maculata, Sthenelais 
boa, and TropTionia plumosa ; but Phyllodoce maculata and 
Sthenelais are as common in sand itself. Stones resting on 
mud form favourite lurking-places for Cirratulus. By 
digging in sand one may obtain Arenicola, species of 
Nephthys, Glycera, Nerine, as well as other forms. Of the 
tube-dwellers, the numerous Terebellids, the curious Sabel- 
laria, and the comb- worm (Pectinaria) all form their houses 
of sand. The Sabellids have usually tubes made of mud,, 
while the Serpulids make white limy tubes. The excep- 
tional habitat of Nereis fucata within the shell of the 
hermit-crab should also be noticed. 

As already noticed, apart from the bristle-worms, other 
"worms" occur on the shore rocks. A few only of these 
can be mentioned. There are first some interesting leaf-like 
flat worms known as Turbellaria, of which a common 
example is Leptoplana tremellaris, the "living film." It is 
a charming little creature barely an inch in length, of a 
delicate brownish tint, and so thin that it is really a mere 


film. It is not uncommon under stones on the shore, but 
requires a trained eye to distinguish it. When turning over 
stones in search of worms it may be that on the upturned 
surface, among sponges, tunicates, and what not, you are 
struck by a delicate film which glides over all obstructions 
with the smooth movement of a drop of water over a 
polished surface. Slip a blunt knife carefully beneath it, 
and drop it into your collecting-bottle. You will notice that 
it swims through the water by vigorous flaps of the body, 
with a motion which has been compared to that of a skate. 
As it settles again on the edge of the bottle, notice with a 
lens that the mouth is on the mid-ventral surface, and that 
the greatly branched alimentary canal is visible, ramifying 
throughout the greater part of the body. There is no 
distinction in appearance between anterior and posterior 
end, except that the anterior is furnished with little black 
specks the eyes. The little creature will live for a time 
in captivity, and the grace of its movements makes it a 
charming inhabitant of the aquarium. The details of 
structure are too difficult for our purpose, but the animal 
is worth mention, if only on psychological grounds. It is 
far from uncommon, and yet many diligent shore hunters 
never find it at all. If, therefore, you find no difficulty in 
obtaining specimens, you may flatter yourself that you have 
acquired the first essential of a shore naturalist quick 

Sometimes associated with Turbellaria are another set of 
flat worms, the Nemerteans, or ribbon-worms. Many of 
these occur on the shore, but we shall limit ourselves to 
two the pink ribbon-worm (Amphiporus lactifloreus) and 
the great sea-snake (Linens marinus). Under stones at all 
parts of the shore one may find the pink ribbon-worm, 
living in a slight tube made of sand cemented together by 
mucus. It is one to two inches in length, but is extra- 
ordinarily contractile. From a bristle-worm it differs 
markedly in the absence of bristles or any sign of segmenta- 
tion. In the head region the eyes will be noticed, and also 
two slits at either side of the head. These are eminently 
characteristic of the ribbon-worms in general. So also is 
the so-called proboscis, a slender thread which the worm 
may be seen to protrude from a pore above the mouth, 


when alarmed or injured. The worm is very common, and 
though not particularly active in its movements, is an 
interesting little creature. 

The big sea-snake (Linens marinus) is usually only to be 
found far out on the rocks near low-tide mark, but is there 
common enough. It is a 
splendid animal, varying in 
length from about three feet 
up to many yards, but not 
much thicker than the boot- 
lace to which fishermen 
compare it. The colour is 
usually said to be black, 
but in reality in life is a 
beautiful changing purple, 
soft and velvety in tint. 
The animal, like all its 
allies, is somewhat slimy, 
and has a habit of coiling 

itself in strange knots, but FIG. 40. Linens marinus, the sea-snake. 

it is nevertheless exceed- fc, head with slits, 

ingly beautiful. Readers of Kingsley's Glaucus will perhaps 
protest at the adjective, remembering the pages of energetic 
vituperation which the author hurls at the unfortunate 
animal, but I cannot think that anyone who studies it 
without prejudice can fail to be struck by the beauty of the 

Like other ribbon-worms, Linens has head-slits at the 
sides of the head, and a long proboscis. It lives well in 
confinement, but usually conceals itself under stones, or in 
sand agglutinated by its own secretion. Like all its allies, 
it is extremely brittle, breaking into pieces on the slightest 
provocation. It is in consequence very difficult to obtain 
perfect specimens for preservation. 

The last group of "worms" we shall mention is the 
Polyzoa curious, much modified forms, which live in colonies, 
and are not unlike "zoophytes." The commonest is Flustra, 
the sea-mat, which is very common in a dry state on the 
beach, and is often called a seaweed. These dried specimens 
are in reality merely the houses of the dead worms. A 
close examination of a piece of sea-mat will show that it is 



made up of very numerous whitish cells or chambers, each 
of which once contained a worm. Living Polyzoa are quite 
common on the shore rocks. Among those to be found 
there in the active condition may be mentioned Flustrella, 
which forms a soft brownish encrustation on the stalks of 
Fucus, and has its surface covered by numerous spines; 
Membranipora, which spreads like delicate lacework over 
the broad fronds of Laminaria; and many others. None of 
them can be properly studied without the aid of a micro- 
scope, and are only mentioned here because they are sure to 
be encountered, and may puzzle the student. 

A. Anterior region with well- B. Anterior region with few 

developed tactile organs. Para 
podia well-developed locomotor 
organs, usually with dorsal and 
ventral cirri. 


ex :} 

Dorsal cirri 

Dorsal cirri form 
filamentous sen- 
sory organs 

tactile organs, often Avith nu- 
merous respiratory organs. 
Parapodia reduced, cirri absent, 
or dorsal cirri represented by 

f Aphroditidae \See previous 
\Phyllodocidse / chapter. 



Prostomium short. 

Dorsal cirri absent 
or indistinct . > 


Prostomium iuiig,-v 

Gill when pre- VGlyceridee 
sent dorsal J 



Head without ap-^ 
pendages. Pros- 1 
tomium fused to | 
peristomium . j 

Prostomium with-\ 
out appendages, 
with two tenta- V 
cular cirri. Gills 
curved over I 
back . J 

Arenicolidse . Arenicola. 

. Spionidae . Nerine. 



r Gills filamentous, \ 

C' t lid 

numerous . / 


absent. (jUls 

Gills branched, ^ 
segments nu- V 
merous . . J 

Terebellidse . 

filamentous or 

Gills branched, 1 


segments few, 1 
anterior crown j 


* of bristles . J 

Prostomium with\ 

palps and nu- 

merous tentacles 1 
(gills). Anterior f 


bristles forming 

a cage for head, j 

Prostomium with" 1 

palps split up to 
form a branchial 

Tubes of sand or\ 
>. mud . . f 


crown. Peristo- 
mium forming a 

Tubes limy 


collar . . j 

Prostomium with \ 

palps split up to 

form rows of 


filaments. Peri- 

^ lubes sandy, ag- \ 


stomium form- 

gregated. . . J 

ing a hood edged 

with bristles 





Fam. Nereidse. 

Nereis. In N. pelagica the back is strongly arched, the palps are 
long, the peristomium or first segment is twice as long as the 
second. In N. dumerilii the cirri are very long; the longest 
of those borne on the peristomium reaches to the fifteenth 
segment. In N. cultrifera the dorsal cirri are short and the 
back flattened. In N. fucata, the posterior feet differ from 
the anterior, and have a long, arched dorsal lobe. In 
N. virens the dorsal lobes of all 

Fam. Nephthydidse. 

Nepldhys. In N. Jwmbergii the head is pentagonal, with four 
minute tentacles; palps are absent. The peristomium has a 
rudimentary foot and a cirrus, but otherwise there are no 
dorsal cirri. Lobes of feet widely separated, with curved 
gill between. 

the feet bear large leafy 


Fam. Glyceridse. 

Glycera. Prostomium in G. capitata is very long, and bears four 
minute tentacles at its tip, and a pair of minute palps at its 
base. There are no gills. The dorsal cirrus is reduced to a 
mere knob, and the. ventral is small. 

Fam. Arenicolidse. 

Arenicola. In A. piscatorum there are thirteen pairs of gills, and 
a gill-less tail region behind these. 

Fam. Spionidse. 

Nerine. In N. coniocephala the prostomium is conical, in N. 
vulgaris it is T-shaped. 

Fam. Cirratulidae. 

Cirratulus. In 0. cirratus a transverse row of tentacular filaments 
occurs immediately behind the head. The gills are present 
chiefly in the anterior region. 

Fam. Terebellidse. 

Terebella. In T. conchilega there are three pairs of gills placed on 
segments two to four, and fourteen to seventeen pairs of red 
gland-shields on the under surface. 

Fam. Amphictenidse. 

Pectinaria. In P. belgica the tube is straight. There are two 
pairs of gills. 

Fam. Chlorhsemidse. 

Trophonia. In T. plumosa, there are two long tentacles and eight 
short gills on the head, which is inclosed in a "cage" 
of bristles. 

Fam. Sabellidse. 

Dasychone. In D. bombyx the back of the gill -filaments bears 
distinct dark-coloured eyes. 

Fam. Serpulidoe. 

Pomatoceros. In P. triqueter the operculum is limy, and bears at 
the sides two horny processes. 


Perhaps one of the most striking points in regard to the distribution 
of the worms mentioned is the great size and abundance of Nereis 
pelagica on the North-east, and its comparative rarity and small size 
on the South and West. On the other hand, Nereis dumerilii is much 
larger on the West Coast than on the East, and is apparently more 
abundant on the former coast. The Sabellids are perhaps commoner 
between tide-marks on the South and West. Generally, however, 
the worms mentioned are widely distributed round our coasts, subject 
to local variation dependent on food-supply, suitable localities, and 
so on. 



General characters of common starfish The characters of Echino- 
derms and the classes The starfishes ami their colour varieties 
The brittle-stars and their peculiarities of structure The sand- 
stars Methods of preserving starfish and brittle-stars The sea- 
urchins Characters of regular urchins Structure of the shell 
Internal anatomy The heart-urchin, its habitat and structure 
Contrast with regular urchins The Holothurians Cucumaria and 
Synapta Development of Echinoderms. 

IN the present chapter we shall be concerned with a very 
interesting group of animals which are singularly well 
defined, and not closely related to any others. Some of the 
general characters of the Echinoderms have already been 
noticed, others will appear during the course of a prelimi- 
nary examination of the common starfish, or five-finger. 
This is to be found in abundance on the shore, especially 
in the vicinity of mussel beds. It feeds on bivalves of 
various kinds, and does great damage to mussel and oyster 
beds. In the neighbourhood of these it grows to a great 
size, specimens measuring a foot from tip to tip of opposite 
rays not being uncommon; but on the shore rocks, away 
from such an extensive food-supply, the usual size is much 
less. In collecting specimens for examination, you are 
certain, sooner or later, to encounter individuals strikingly 
different from the normal. They may have one large ray 
and four small, or any combination of small and large rays. 
These illustrate one of the striking peculiarities of the 
Echinoderms their capacity for regenerating lost parts. 
In many cases, notably in the brittle-stars, the animals 
throw off portions of their bodies when attacked ; in other 
cases, though the animals do not practise self-mutilation to 



any extent, they possess an extraordinary power of repair- 
ing accidental injuries. 

Having collected some specimens of the common starfish 
and placed them in sea-water, the external characteristics 
can be readily made out. The fact that there are five rays 
is very obvious, as is also the prickly skin, the ventral 
mouth, and the five grooves which radiate from the mouth 
and contain the transparent tube-feet. When the starfish 
is lifted up from the surface to which it is adhering, it will 
be noticed that it is attached to this surface by the tube- 
feet, which end in suckers. So firmly do the suckers cling 
that it often happens that when the animal is removed from 
the rock, some of the tube-feet break through rather than 
let go. When the animal is held in the hand it is easy to 
feel the limy plates in the skin, and a dried skeletonised 
specimen picked from the beach will show you the beautiful 
arrangement of ossicles, or limy plates, which bound the 
ventral groove along which the tube-feet lie. On the dorsal 
surface notice between two of the rays a white plate, called 
the madreporite, or rose-plate, which is perforated by numer- 
ous holes through which the sea-water enters the system of 
canals which supplies the tube-feet. These become tense 
or flaccid according to the amount of fluid they contain, and 
being alternately fixed and loosened, serve not only for 
attachment to rock surfaces, but also for leisurely pro- 
gression. This may occur in any direction, for the starfish 
being radially symmetrical like a flower, or a sea-anemone, 
has no head no specialised region which always moves 
foremost. The radial symmetry (usually based on the num- 
ber five), the limy skin, the peculiar tube-feet, which are 
part of the "water-vascular" system, the power of re- 
generation and frequently of self-mutilation, comprise the 
most obvious of the external characters of the Echinoderms. 
There are five living classes : 

1. Starfishes (Asteroids). 

2. Brittle-stars (Ophiuroids). 

3. Sea-urchins (Echinoids). 

4. Sea-lilies (Crinoids). 

5. Sea-cucumbers (Holothurians). 

But of these the sea-lilies only occur in deep water, mostly 


only in the great depths, and the sea-cucumbers are rare 
between tide-marks, at least on the East Coast; so that 
practically our studies of the group must be confined to the 
starfishes, brittle-stars, and sea-urchins. Even of these we 
have very few littoral species, so there should be no diffi- 
culty in learning to recognise all the common forms. We 
may conveniently begin with the starfishes, in which the 
body is distinctly star-shaped, but has often more than five 
arms, has an open ambulacral groove (or groove containing 
the tube-feet) on the ventral surface of each arm, or ray, 
and has both the digestive and the reproductive organs pro- 
longed into the stout arms. 

The common starfish, Asterias rubens, is perhaps the most 
abundant form, and we may describe its peculiarities first. 
As in most shore Echinoderms the colour is very variable 
red, orange, purple being the commonest tints. The limy 
plates in the skin are netted, or reticulate, and bear numerous 
small spines. A row of these spines runs down the middle 
of each arm, but in very large specimens this regularity of 
arrangement is not obvious near the ends of the rays. 
Scattered among the spines are pedicellarice, or little stalked 
forceps. The tube-feet are arranged in four rows, and the 
sides of the ambulacral groove are furnished with two rows 
of spines. To the outer sides of these spines there are 
three rows of closely crowded spines. We have already 
noticed the frequent occurrence of specimens showing re- 
generation of lost or injured parts. In some places this 
starfish is extraordinarily common, and occurs in numbers 
in every rocky crevice. St. Andrews and Joppa may be 
specially mentioned as spots where I have found it very 
abundant. On the West Coast there occurs, in addition, 
the larger and handsomer Asterias gladalis, which has 
larger and more numerous spines, arranged in several regular 
rows down the arms ; but this does not occur on the East. 

Almost equally common with Asterias rubens is another 
smaller five-rayed starfish which occurs in many colour 
varieties purple, purplish red, pure red, orange, all being 
common. It is more compact in shape than the common 
starfish, and contains so much lime that it is exceedingly stiff 
and does not droop flaccidly when lifted up as that animal 
does. This is Henricia sanguinolenta, and it has also a 



distinctly reticulate or netted skeleton, with minute spines 
on the meshes of the net. Between the meshes there are 
in some places pores through which little sacs, or skin-gills, 
can be protruded. The rays taper very gradually, and have 
a very narrow ventral groove with two rows of tube-feet. 
At the sides of the groove there are dense rows of small 
spines. The species is interesting because it extends over a 
very wide area, not only horizontally but also vertically; for 
it lives from the shore down to great depths. About two to 
four inches from ray to ray may be given as a common size 
for shore specimens, though the animal does grow to a much 
larger size. It is very variable, varying greatly not only as 
to colour, but also as to the degree of development of the 
spines, and even the number of rays. It is not uncommon 
to find four- or six-rayed specimens, though normally the 
number is five. 

Our list of littoral starfishes is so short that when we 
have named the sun-star (Solaster papposus, see Fig. 41), 

we have named all 
that are likely to 
occur in the living 
state between tide- 
marks on the East 
Coast. Our common 
sun-star reaches a 
large size, and may 
be recognised by the 
fact that it has twelve 
or more rays. Like 
so many starfishes, 
it varies greatly in 
colour usually pur- 
plish red blotched 
with white, it is 
sometimes pure red, 
and sometimes 
orange. The dorsal 
surface is covered with peculiar spines of large size, which 
are separated by spaces through which the little skin-gills 
emerge in life. Each of these dorsal spines consists of a 
pillar, bearing at its top a cluster of crowded spines, pro- 

Fio. 41. Solaster papposus, or sun-star. Note the 
round madreporite to the left of the central disc. 



ducing the appearance of a little brush. At the sides of 
the short rays there are prominent lateral spines of simple 
structure. There can be no difficulty in recognising the 
sun-star, but it is interesting to notice how it differs from 
another species, Solaster endeca, which is sometimes flung 
on the beach by storms. This has nine to eleven arms, is 
usually purple, not purplish red, has more numerous dorsal 
spines more closely packed together, and less distinct lateral 

After the starfishes we come to the Ophiuroids, or brittle- 
stars, which from their shape and habits are perhaps less 
conspicuous than 
the starfishes, but 
are quite as abund- 
ant. They are to 
be found under 
stones or among 
weed, twining 
their, long snaky 
arms about the 
surrounding ob- 
jects, and snap- 
ping them off at 
a touch. At least 
three species are 
common in the 
living condition 
between tide- 
marks, and others 
occur at times after storms. Instead of giving a formal 
definition of the group, let us look at the general charac- 
ters of our common brittle-star (Ophiothrix fragilis, see 
Fig. 42). It is especially abundant among the roots of 
oar- weed, and a few specimens should be extricated with 
care and put into clean water. Notice first the much 
greater activity than that displayed by starfish ; it is often 
difficult to say whether a specimen of the latter is alive or 
dead, so limp and flaccid does it appear even when taken 
fresh from its pool. The brittle-star, on the other hand, is 
continually wriggling its arms, and can progress rapidly by 
their means at a rate which has been estimated at about 

FIG. 42. Common brittle-star (OphiotJirix fragilis). 
r, radial shield ; sp, spines. 



twenty times that attained by the common starfish. The 
arms, or rays, are very long and slender, so slender that 
there is no difficulty in realising that they do not, like 
those of the starfish, contain prolongations of the digestive 
organs, which here, like the reproductive organs, are con- 
fined to the disc. The tube-feet are also reduced, are no 
longer placed in an open ambulacral groove, are not used 
in locomotion, and are small and tentacle-like in appearance. 
Between the rays there are peculiar bursse (b in Fig. 43), or 

pockets, which open to 
the exterior by deep 
slits placed at the sides 
jof the rays. These are 
breathing organs, and 
are very characteristic 
of brittle -stars. 

This general survey 
of a brittle-star should 
make the main points of 
contrast with starfish 
clear, but the details of 
structure are difficult ; 
we can only indicate the 
more important points. 

FIG. 43. Diagrammatic view of the under First, as to the ravs : 
surface of the disc in the sand-star , , -i i 

(Ophiura). Of the five rays three are cut among the dried Wreck- 

short close to the disc, the other two just OCTP npnr Vn'rrh rirlp mirL- 

beyond its limits. In the centre is the star- a 6 near HlgH-tlde mark, 

like mouth; the tiiangular plates which yOU Will always find 

project into it are fringed by mouth- olrolafnTn'onrl V.ffl of^-r, 

papillae. The presence of teeth is also Skeletonised brittle-stars 

indicated. ft, one of the bursal slits ; ms, which will show that 

one of the mouth-shields; s. arm-spines. ,1 , 

the arms are made up 

of a series of segments or vertebrae, jointed together. Out- 
side these segments there are a series of plates, one of 
which is placed on the dorsal surface of each segment, one 
on the ventral, and two at the sides. These last, the lateral, 
plates bear spines. The delicate tube-feet emerge at the 
side of the rays, and there are one or two little plates, 
called the tentacle scales, at the point of exit. In regard 
to the disc the dorsal surface is variously marked in the 
different species, but there are usually two distinct plates, 
called radial shields, at the origin of each ray. On the 


ventral surface we have the mouth, which has a complicated 
structure. The main points are indicated in Fig. 43, which 
is a diagram of the parts in the sand-star (Ophiurd). The 
actual mouth -opening is small, for from its margin five 
triangular projections jut inwards, the apex of the triangles 
being towards the centre. These projections arise be- 
tween the arms, and as they do not touch one another, 
the mouth-cavity consists of a small central space con- 
tinued into five slits, the slits corresponding to the rays. 
Into these slit-like spaces the first tube-feet of each ray 
project, and function as tentacles. The minute structure 
of the triangular projections is of some importance in 
identifying species. Each consists of a basal plate, or 
mouth-shield, and two lateral plates in contact through- 
out the whole or part of their length. In some cases these 
lateral plates bear small spines at their edges, so that the 
mouth-clefts are fringed by spines. Such spines are called 
mouth-papillae. Again, spines may be present at the apex 
of the triangle, such spines being called tooth -papillae. 
Finally, beneath the tooth-papillae, and within the mouth- 
cavity, there may be smaller spines called teeth. The 
madreporite in brittle-stars is on the ventral surface, and 
not the dorsal as in starfish, and replaces one of the mouth- 

The common brittle-star (Opliiothrix fragilis), which in 
most places is very common, is to be found under stones 
and among tangles between tide-marks. Fair-sized speci- 
mens measure three to four inches from tip to tip, but the 
arms are very brittle, and break off at very slight provo- 
cation. The colours are bright and variable, the rays being 
usually banded, and the disc of a contrasting colour. Keds, 
browns, and yellows are common tints, but the rays are 
frequently violet or grey. The arms are flattened, and the 
most characteristic point is the presence of long notched 
glassy spines borne at the sides of the arms in bunches of 
seven. Some other more minute points of structure may 
be given as follows. There are no mouth-papillae, so that 
the sides of mouth-clefts are unnotched, but there are 
numerous tooth-papillae and teeth. On the dorsal surface 
of the disc the radial shields are very conspicuous, but the 
rest of the disc shows much variation in the presence or 


absence of spines. The whole animal, indeed, shows much 
variation, and it is so common that it is interesting to study 
the variation in detail for any locality. 

Almost as abundant as the common brittle-star is the 
daisy brittle-star, which occurs in similar localities. The 
differences between the two are not very easily described, 
though an examination of actual specimens should make 
them obvious enough. Perhaps the most obvious difference 
is in the spines, which in the "daisy" are short and stout. 
The arms themselves are wide and flat, less fragile, and not 
so long as in Ophiotlirixfragilis. They are usually beautifully 
banded with alternate bars of red and white. There is no 
difficulty in learning to distinguish these two common 
brittle-stars by what may be described as mere "rule of 
thumb," but those who care to make their knowledge exact 
may welcome a brief account of the more minute peculiarities 
of the " daisy." Its scientific name is Opliiopholis aculeata, 
and among its notable characteristics are the fact that the 
upper arm plates are surrounded by small additional plates, 
that the disc is so covered by granules that the radial 
plates are rendered obscure, and that while teeth-papillse 
are absgnt, three mouth-papillae are present at each side of 
the mouth-clefts. The spines borne by the lateral arm 
plates are seven in number, and, as already stated, are short 
and stout. 

Both the common and the daisy brittle-stars live fairly 
well in confinement, especially in the case of small specimens, 
and they are well worth the careful study which can be 
most readily bestowed on captive specimens. Like other 
brittle-stars, they are somewhat difficult to study and to 
name, both on account of the complexity of their hard 
parts, and of the great colour variability. As regards the 
question of naming your specimens, one hint may be given, 
though it is one the beginner is apt to resent it is, do not 
forget to look at your specimens before you try to name 
them. Very many people who are interested in natural 
objects begin systematic work with British flowering plants, 
and are then apt to acquire the pernicious habit of naming 
specimens by what one may describe as a mere trick the 
shape of the petals, or of the fruit, or some other single 
point. The educative value of species work, however, 


certainly in the case of animals at least, is its training in 
the perception of form, and one should strive to learn not 
merely to count or measure spines, but to perceive those 
real differences of form which are often so difficult to 
explain in words, but which constitute the true distinctions 
between species. The brittle-stars are especially adapted 
for exercises of this kind, and before you begin to study 
the minute details of structure, you should strive to acquire 
an exact knowledge of the general form. It is an interesting 
if somewhat humiliating experience to look at a brittle-star 
for a few minutes, then to cover it up and endeavour either 
to draw or to even merely visualise the specimen, and then 
compare your mental image or your sketch with the real 
object. Both generally leave much to be desired in the way 
of precision. 

There are a considerable number of other brittle-stars, or 
sand-stars, which may occur between tide-marks, especially 
after storms. One which occurs there freely in the living 
condition, but is liable to be overlooked on account of its 
small size, is Amphiura elegans. It should be looked for 
under stones, and does not usually exceed one inch to one 
and a half inches in length. The colours are sober and 
inconspicuous, and the creature may be recognised by its 
round disc with well-marked radial shields, and the slender 
arms whose side plates bear three to four inconspicuous 
spines. There are three mouth-papillae on either side of 
the mouth-clefts. After storms, or among the wreckage at 
most seasons of the year, the common sand-stars Ophiura 
lacertosa and 0. alUda are to be found. They can be 
recognised by the fact that the disc is cleft at the origin of 
the arms, the clefts being fringed by papillae. In the larger, 
0. lacertosa, these papillae are ten to twelve in number, 
while in the smaller, 0. albida, they number about thirty. 
The arms bear only minute spines, which are so closely 
adpressed to the sides of the arms that they are not seen on 
casual view. The disc is completely covered with scales. 
The sand-stars occur perhaps most frequently in the 
skeletonised condition, high up on the shore, and are then 
admirable subjects for the study of the Ophiuroid skeleton 
(see Fig. 43). 

The Ophiuroids in general offer many interesting points 


of contrast with the starfishes. While in the latter it is 
common to find that the arms exceed five in number, in the 
Ophiuroids this is not the case. As the name brittle-star 
indicates, the Ophiuroids are generally very fragile, but the 
somewhat rare starfish Luidia shows that the same fragility 
may occur in the Asteroids. Indeed, though our British 
Asteroids and Ophiuroids are sharply marked off from one 
another, when the groups are considered as a whole their 
close relation becomes obvious. 

On account of the large amount of lime in the tissues, 
the starfishes and some of the Ophiuroids make good dry 
preparations, and are often most easily preserved in this 
way. In the case of the larger starfish it is desirable to 
remove some of the water from the tissues before allowing 
the specimens to dry. This is best accomplished by placing 
the animal in spirit for twenty-four hours, changing the 
spirit once during that time. This "dehydrating" process 
may be conveniently carried out in a pie-dish covered by a 
plate. Afterwards the starfish should be lifted out and 
allowed to dry slowly in air ; a well-ventilated outhouse, or, 
in default of it, a shady window-ledge, is a good situation 
for the process. The dried specimens should be kept in a 
cabinet with camphor or some other preservative against the 
attacks of insects; if they become damp, or show signs of 
" going wrong " in any way, a repetition of the dehydrating 
and drying process is often effective. In the case of the 
brittle-stars, the prime difficulty is usually to obtain a 
perfect specimen either to dry or to preserve, for the animals 
usually break up in dying. In some cases at least specimens 
may be instantly killed without rupture by dropping them 
suddenly into boiling water, and as death is practically 
instantaneous, the objection of the apparent cruelty need 
hardly be entertained apart from the other debated 
question how much a brainless animal like an Ophiuroid 
can really "feel." Specimens killed in this way become 
abnormally brittle after death, and must be handled with 
extreme caution. 

The next set of Echinoderms is constituted by the sea- 
urchins, which have this advantage over the brittle-stars 
that they are more or less familiar to everyone. To study 
the general characters you should provide yourself with a 


good number of the empty shells, or tests, which usually 
ornament cottage windows near the sea, and are to be found 
on the beach at most seasons of the year. In addition, an 
attempt should be made to obtain one or two living 
specimens. It is not always easy to obtain the common 
urchin (Echinus esculentus) in the living condition, but the 
small purple-tipped urchin (E. miliaris) may generally be 
found in the Laminarian zone, and has the advantage that 
one may keep it alive in confinement longer than its relative, 
which needs a great bulk of water. 

Let us examine the living specimens first. The common 
urchin is really an inhabitant of fairly deep water, but I 
have often taken single 'specimens at low spring tides, and 
where the shore slopes steeply the urchins may sometimes 
be seen in numbers by looking over the edge of the rocks. 
The colour is usually purplish pink, but I have found 
specimens entirely straw coloured, with beautiful purple 
tube-feet. The test is rounded, and in life covered by 
numerous long spines. In E. miliaris, which is very much 
smaller, the diameter often not exceeding that of a penny, 
the test is flattened, and the numerous spines are short and 
not of uniform size. The general tint is green, but the 
spines are tipped with purple. In either urchin you will 
notice the mouth in the middle of the under surface. It is 
surrounded by a membrane which is very extensile, so that 
the mouth can be protruded to a considerable extent, and 
then withdrawn. The object of this, as a living active 
urchin will show, is to allow of the free movement of a 
complicated tooth-bearing structure called Aristotle's lantern. 
This contains a circle of five chisel-edged teeth (see Fig. 44) 
which may be seen and felt in the mouth of the urchin, and 
are borne by an arrangement of ossicles, which permit the 
teeth to open and close so that the urchin can crop seaweed 
as effectually as a rabbit crops dandelions. Their action is 
greatly aided by the elastic mouth membrane, which is 
covered by small tube-feet which act as tentacles, and by 
little stalked forceps called pedicellarias, curious structures 
common among the Echinoderms, and probably serving to 
keep the test clean. 

The presence of this mouth-membrane and of Aristotle's 
lantern has a rather interesting effect in the case of dried 


specimens. If you have a fair collection of these, you will 
probably find among them some which present much the same 
appearance as the living specimens, spines, mouth-membrane, 
and teeth all being present as usual. In not a few cases, how- 
ever, you will notice that the soft membrane shows signs of 
decay either it cracks in dying, or it is attacked by sand- 
hoppers or some of the shore insects. The result is to set 
free the bulky and heavy lantern. This may then simply 
fall out of the empty test, and be found lying intact on the 
sand, or more probably its ligaments speedily decay and one 
finds merely the scattered ossicles and teeth among the 
wreckage. By the decay of the membrane the cavity of 
the urchin is fully exposed, and the soft parts are speedily 

FIG. 44. Portions of Aristotle's lantern from a sea-urchin, 
a, external view of the lantern, showing two of the five main 
pieces (alveoli) of which it is composed ; b, internal view of 
single piece ; c, side view ; t, in each figure, one of the five 
chisel-edged teeth, which run through the alveoli and are 
carried by them. 

eaten up, or dried up by the sun. The test then becomes 
very light, is rolled over and over by the waves, so that the 
spines are removed, and there is left the familiar empty 
shell with a gaping orifice beneath, and a surface covered by 
white knobs which show the places where the spines were 
formerly attached. In other cases the disintegration of the 
membrane is only partial, and the lantern merely falls into 
the cavity of the urchin. Specimens of this kind often 
occur with the lantern loose inside, and rattling at every 
movement. As the lantern is heavy, the result in this case 
is often to break the test in pieces, when the separated 
waterworn pieces appear on the shore as what children call 
"sailor's cheese." 

After this digression we may return to our living urchin. 


More obvious than mouth and teeth are usually the long 
slender tube-feet, which form five double bands over the 
test, and can be stretched out to a great length. They, 
indeed, give the sea-urchin a great part of its beauty, and in 
life are in constant movement, now extended, now con- 
tracted. By this means the sea-urchin is enabled to crawl 
up a perpendicular surface. The only other point which 
can be readily observed in the living urchin is the posterior 
opening of the food canal at the point opposite to the mouth. 
It is surrounded by small plates of lime, and, as these are 
readily removed, is in consequence often represented by a 
large hole in dried specimens. 

To study the composition of the urchin's test in detail we 
must return to the dried specimens from which the spines 
have been rubbed off. As already noticed, the mouth is 
usually now represented only by a gaping hole, by which 
the lantern has been shaken out. The anus may or may 
not have lost its small plates, but around it will be seen ten 
distinct plates, which mark out as many radii on the shell. 
Five of these plates bear each a distinct round hole, which 
is the opening of the reproductive duct, but one of the five 
is in addition perforated by minute holes, and so constitutes 
the madreporite. The other five plates are smaller, and 
bear each an eye-spot. In a line with these five plates 
are the five ambulacral areas of the test, which each 
consist of two rows of plates perforated by the minute 
pores through which the tube-feet emerge. In addition 
these plates, which are relatively narrow, bear a few spines. 
Corresponding to the larger plates, and thus alternating 
with the ambulacral areas, are five interambulacral areas, 
each consisting of a double row of wide plates, bearing 
numerous spines. The net result is to produce in the living 
urchin five double rows of tube-feet, separated from each 
other by a somewhat wide interval thickly covered with 
spines. The spines have a curious ball-and-socket joint at 
the base, and are very freely movable. They assist in 
locomotion, and must also protect the test from mechani- 
cal injury. The large urchin lives freely exposed, and 
probably from its strong armour has little to fear from 
the attacks of enemies ; but the little purple-tipped urchin 
covers itself with weed and fragments of stone and shell as 



though to seek protection. It is in consequence not very 
easily seen except by careful search, but is common enough 
in the Laminarian zone. The depressed shape and green 
and purple colour make it easily recognised. As already 
indicated, the common urchin only occurs somewhat sporadi- 
cally between tide-marks, but it is at times thrown on shore 
in great numbers after gales, and is generally to be found 
in the dry condition on the beach. The diet of both 
urchins seems to vary, probably in part according to the 
locality; in many places both live largely on seaweed, but 
are not averse to mingling this with animal matter. 

In both cases 
the internal anat- 
omy is very in- 
teresting, and a 
general notion of 
its main outlines 
is easily obtained. 
With a strong 
pair of scissors 
make a circular 
incision midway 
between mouth 
and anus, and then 
lift off the upper 
segment. In it 

FIG. 45. Echinus esculentus. common sea-urchin. The nr > p PPQ flip fiva 

r' ies have been removed from half the test, to u /& . MM 

w the structure of the latter. The reference reproductive or- 
lines (a) inclose an ambulacral area; i is an inter- vowin^ 

ambulacral area. & clllb > Vcll j lli 5 

greatly in size ac- 
cording to the season of the year; in the lower we see 
Aristotle's lantern, which is very large relatively to the 
size of the animal, and is perforated by the brown ali- 
mentary canal, which, after leaving the lantern, coils about 
the shell, and ultimately passes upwards to end at the 
anus. Notice also the stone canal, a tube hanging verti- 
cally from the madreporite, which opens into a ring canal 
placed on the lantern, which again opens into five radial 
canals running along the inner side of the ambulacral 
areas. Each radial canal communicates by lateral branches 
with the tube -feet, and with the leaf -like ampullw 


which lie on the inner side of the shell, and form very 
conspicuous objects. Perhaps, however, in the common 
urchin at least, you will be most struck by the apparent 
emptiness of the shell. It contains a large amount of 
watery perivisceral fluid, but even when the urchin is fully 
ripe seems disproportionately large relatively to the con- 
tained organs. It should be noticed that the shell is not 
an external structure like the coat of a crab, for its outer 
surface is covered by a thin layer of skin, and in develop- 
ment it arises as an internal skeleton. The separate plates 
of which it is composed go on growing during life, and in 
this way the whole test increases in size as the urchin 
grows older. 

These two urchins are the commonest of our regular 
urchins, which are characterised by their more or less 
spherical shape and the regular arrangement of their tube- 
feet in five double rows. The majority of the internal 
organs, reproductive organs, nerves, ambulacral canals, etc., 
occur in fives; or, in other words, the symmetry is penta- 
merous throughout. It is otherwise with the next urchin 
to be considered, which has a less well developed ambulacral 
system, and shows a tendency to lose this five-rayed symmetry 
in favour of a bilateral arrangement. There are a number 
of such irregular urchins, but the commonest is perhaps 
Ecliinocardium cordatum, which shares with some of its 
allies the popular name of heart-urchin. The heart-urchins 
are most interesting animals, interesting both in themselves 
and in their contrast with the common urchins. To get 
Echinocardium in the living state one must be prepared to 
risk a good deal in the way of wet feet. If the enthusiasm 
of the naturalist rises above this objection, the next desi- 
deratum is a strong spade not a toy, but the genuine 
article borrowed from the gardener and a good low spring 
tide. The last is in most cases essential. Then choose a 
spot where the tide ebbs a long distance over sand which is 
shown, by abundant worm-castings and mollusc shells, to be 
suited to animal life, and begin work at the margin of the 
water. It may be well to repeat warnings already given as 
to the force of spring tides and the possible element of 
danger in shore hunting at that period. In most cases the 
tide rushes in over those long level flats, beloved of sand- 


dwellers, with great rapidity, and the enthusiastic naturalist 
is often wise to take with him a cautious and unenthusiastic 
companion and a flat-bottomed boat. He will soon learn by 
experience whether the element of safety imparted by the 
presence of the boat compensates for the trouble of wading 
for perhaps half a mile through water too shallow for it to 
move or laboriously pushing it over the sandy flats. All 
these are mere trifles to the genuine enthusiast, and if the 
ground be rich, sand digging becomes a delightful and profit- 
able amusement. You may get many curious creatures, but 
there is at least this satisfaction in regard to the heart- 
urchins, that if you find any at all you are pretty sure to 
find as many as you can possibly want. They occur at no 
great depth below the surface, in burrows of their own 
making, and many are at times turned up in each spadeful 
of sand. In life they are of a beautiful golden colour, 
which unfortunately speedily fades after death, and the tests 
are so fragile that they are often broken to pieces in the 
mere handling and separating from the sand. 

As regards structure, notice first the silky spines, which 
vary much in size, and are not uniformly distributed over 
the surface. The test is somewhat heart-shaped, and flattened 
beneath, and the mouth will be found on this lower flattened 
surface, overhung by a lip-like process, but without any 
trace of a lantern. Round the mouth, and sending two 
diverging horns backwards, is a bare space, perforated, 
especially near the mouth, by pores through which a few 
tube-feet emerge. These are somewhat complicated in 
structure, having curious brush-shaped tips, and function as 
tentacles. Between the posterior diverging horns just men- 
tioned is a group of interesting spines. They are stout and 
flattened at the ends, or spatulate. It is these which are 
used in excavating the burrow, their action being assisted 
by the other spines, which have an interesting and somewhat 
complicated arrangement, well worth careful study, and by 
the mouth process. Next turn over your specimen and 
study the dorsal surface. In a living specimen it is possible 
to make out, though less clearly than in the dry shell, that 
the ambulacral areas in this region show what is called a 
petaloid arrangement, that is, they are arranged roughly 
speaking in the form of a five-rayed star, and are thus 


something like a flower. The odd ray is to the front, and is 
more conspicuous than the others because it is placed in a 
deep groove. On the sides of this groove there are rows of 
spines bent inwards until they nearly meet. Place a living 
specimen before you with the grooved region towards you, 
and you will notice that the slope of the test, the position 
of the groove, and the arrangement of the spines, are all so 
adjusted as to form a definite canal, which leads from the 
crest of the shell straight towards the mouth with its spout- 
like process. Notice also that the tube-feet of the petaloid 
area are extensile and well developed, and so arranged as to 
serve to catch hold of food-particles and sweep them down- 
wards into the groove and so to the mouth. Notice the 
anus near the middle of the vertical posterior region of the 
shell, and the peculiar rounded sub-anal area beneath it, 
which is liable to be mistaken for it. You will also notice, 
what is even more obvious in dissection, that the apertures 
of mouth and anus are very small indeed, showing that the 
animal cannot live upon particles of considerable size, as do 
the regular urchins. 

Having made these observations on the external aspect 
of the living animal, you may proceed to study some of the 
details of anatomy. To do this you should provide yourself 
both with fresh specimens and with a considerable number 
of dried tests, in the condition in which they are to be 
found on every sandy beach. Dissection in the strict sense 
is of course impossible; but a good idea of the anatomy 
may be obtained by cutting open the shells with a strong 
pair of scissors in different directions, so as to get different 
views of the interior. 

Let us consider first the function of nutrition. What 
does the heart-urchin feed upon? The first one you open 
will show, even if you had not previously come to con- 
clusions on the subject from the habitat. It feeds on the 
minute particles contained in sand, and the alimentary canal 
is always filled with sand, which is swept into the mouth 
down the groove in the way of which we have already 
spoken. As sand is abundant, the urchin does not need 
to go and seek its food, but remains more or less passively 
within its burrow, and uses its tube -feet and spines in 
directing the food-supplies to the mouth. The food requires 


no mastication, and so we find that the lantern and its 
supports have disappeared. The position of the anus at 
the posterior end, instead of at the top of the shell as in 
EC) Linus } is probably an adaptation to life in a burrow ; for 
as the urchin's food to a large extent must come from 
above, it is desirable that waste material should not be 
deposited where it might mingle again with the food. 

What effect has this more or less sedentary life had upon 
the ambulacral system ? In the first place it is obvious that 
this has at least very largely lost its locomotor functions. 
The feet have now no suckers; they are not, as in the 
common urchin, arranged so as to make locomotion in every 
direction possible, and indeed the shape of the test would 
render this impossible in any case. The tube-feet now act 
largely as tentacles, and also possess, as in the regular 
urchins, some respiratory function. We have noticed that 
they seem not to be continuous over the whole test, but 
form a petaloid area on the dorsal surface, and a similar 
but less well developed area about the mouth on the ventral 
surface. Careful examination of the interior will, however, 
show you that the radial canals are continuous internally, 
and that the upper and lower petaloid areas are connected 
by regions in which a few small scattered tube-feet occur. 
In the dry shell on the dorsal surface, to the posterior side 
of four pores which you will find near the upper end of 
the groove, you will be able with the aid of a lens to 
discover the madreporite, or rose-plate, which has remained 
in its primitive position, while the anus has moved back- 
wards. Thus we see that the ambulacral system is con- 
structed on the same plan in Echinocardium as in Echinus ; 
but in the former certain of the tube-feet have, as it were, 
been accentuated, at the expense of others which are now 
only very slightly developed. It is interesting to note 
that the irregularity which manifests itself in the external 
appearance of the urchin is also apparent internally in the 
reproductive organs, of which there are now four only 
instead of five. The four pores spoken of above are the 
four genital pores (cf. the five of Echinus). 

This description of Echinocardium will not be found very 
readily intelligible unless it is studied with the help of 
actual specimens, but dried specimens at least are so extra- 



ordinarily plentiful that there is no reason why this should 
not be done. The contrast between the regular urchins 
with their strong shells, uniform coating of spines, and 
well-developed tube-feet, and the heart-urchins with their 
fragile shells, on which both spines and tube-feet are dis- 
tributed in so complex a fashion, and which have lost the 
primitive radiate symmetry, is so striking, and so intimately 
related to the different modes of life, that it is worth 
careful study. A great part of the interest attached to 
the Echinoderma is due to the fact that the members of 
the group show adaptations to many different kinds of life, 
while retaining those well-defined characters which make 
the group such a compact one. In many cases the structural 
adaptations to particular habitats are difficult to study, but 
in the heart-urchins they are fairly obvious, and intensely 
interesting. Between tide-marks EcTiinocardium cordatum 
is the only heart-urchin likely to be found in the living 
condition ; but on the beach after storms one at times finds 
the purple heart-urchin (Spatangus purpureus). The differ- 
ences between it and Echinocardinm are not very striking 
apart from colour. The most noticeable difference is perhaps 
the fact that in Spatangus certain of the spines are very 
long, strong, and curved a difference probably associated 
with the fact that the animal lives in coarser material 
(coarse sand or gravel) than Ediinocardium. 

The next group of Echinoderms the Holothurians, or 
sea-cucumbers is very poorly represented on the East 
Tloast, at any rate in shallow water, though, indeed, in any 
case the majority occur beyond tide-marks. For the sake 
of completeness we may describe a typical form, such as 
Cucumaria ladea, which does occur between tide-marks 
occasionally. It is a little creature, about an inch long, 
with a cylindrical body, and a tough skin of white or brown 
colour. The form is strikingly different from that of other 
Echinoderms, for it is characteristic of the Holothurians 
that their radial symmetry is not obvious, most of them 
being of worm-like form, and showing more or less distinct 
bilateral symmetry. If you obtain Cucumaria in the living 
active condition, you will see it protrude at one end of the 
body a beautiful crown of ten branched tentacles (te in 
Fig. 46). At the other end of the body is the anus, and 


between these two extremities there occur five zigzag rows 
of tube-feet (tf in Fig. 46). These are very different from 
the long, delicate tubes of a sea-urchin, for they are short, 
stiff, and can only be very imperfectly retracted. The 
skeleton, as in all Holothurians, is represented only by 
deposits of lime in the skin, which are not continuous, and 
are not at all conspicuous. The internal anatomy we need 
not consider, but may only remark in passing that most 
Holothurians have a distressing habit of throwing out 
portions of their internal organs when attacked or alarmed. 
In consequence one only rarely gets an intact specimen for 
dissection; even those which seem uninjured will often be 
found when opened to have lost some of the viscera. 


FIG. 46. Sea-cucumber (Cucumaria planci). After Bell, tf, one of the five 
rows of tube-feet ; te, tentacles surrounding the mouth. 

There is one other Holothurian which occurs not un- 
commonly all round our coasts, though it is not often seen. 
If, however, you make that low-tide excursion to a sandy 
beach which has been recommended as the only way of 
getting Echinocardium in the living condition, you will 
probably find among your spoil pink worm-like creatures, 
which you are not unlikely to describe either as " worms," 
or as burrowing sea-anemones. They are slender, trans- 
lucent creatures with an anterior crown of tentacles, and 
are usually about three inches in length. If you examine 
the surface of the body with a lens, and also pass your 
finger over it, you will notice one of the most curious 
characters of Synapta, as the little creature is called. This 
is the presence in the skin of little anchors of lime, whose 


flukes project from the surface and cling to the hand, as 
under natural conditions they do to the sand. This Holo- 
thurian, then, is literally and not metaphorically anchored to 
the sand, the anchors being numerous and scattered all 
over the body. If you examine a fragment of the skin 
under a strong lens or a low power of the microscope, you 
will see that each anchor is connected with a little plate 
perforated by seven or nine holes, and that it can move 
on this plate as on an axis. Plates and anchors together 
represent the limy deposits of Cucumaria, and so the limy 
skeleton of other Echinoderms, and are exceedingly character- 
istic of Synapta. After having once been seen they can 
hardly be mistaken for anything else. I once knew a 
learned professor who was a great admirer of these anchors, 
and used to bring them out with the utmost regularity 
whenever he presided over a zoology examination. Both 
they and their owner are a little out of the way of ordinary 
zoology students' observations, so the candidates came to 
grief time after time through their wild shots on the 
subject, until the professor was ill-advised enough to remark 
in a public address on the ignorance of Synapta which 
prevailed among zoological students. After that all institu- 
tions which sent up candidates to the public examinations 
purchased a slide displaying the anchors, and so succeeded 
in passing their students without the trouble of going to 
dig for Synapta, or studying its structure. 

Associated probably with the burrowing habit of Synapta, 
we have the interesting fact that the tube-feet are absent 
from the body, and are represented only by the crown of 
tentacles at the anterior end. In Cucumaria the tentacles 
are also modified tube-feet, and these are the only ones 
which can be described as well developed. In Synapta the 
tentacles are the only representatives of tube-feet present at 
all. The statement that in Cucumaria and Synapta, as in 
Holothurians in general, the tentacles are modified tube-feet 
is not a mere assertion, but is justified by the relation of 
these tentacles to the ambulacral system, a relation easily 
studied in the larger Holothuria by dissection. 

The only species of Synapta usually to be found between 
tide-marks is S. inhcerens, recognised by its twelve tentacles, 
each with six or seven finger-like processes at either side, 


and by the fact that the edges of the holes of the anchor 
plates are serrated. As is to be expected from the habitat, 
it lives on the organic particles contained in sand, and the 
alimentary canal with its contained sand can be seen shining 
through the transparent body-wall. As in Cucumaria, the 
tentacles can be completely retracted, and the animal is 
then very worm-like in appearance. 

This concludes the consideration of our common littoral 
Echinoderms. The forms mentioned should give the student 
a general idea of the main points of structure, and should 
serve to indicate the general interest of the group. Our 
common littoral forms are adapted to very various conditions 
of life, and while retaining certain common peculiarities of 
structure, present in a most interesting way what are known 
as adaptive characters. One very interesting point in regard 
to the group is, that the development is usually very 
indirect, the larvae being quite unlike the adult, and adapted 
for very different conditions. The larvae of our common 
shore species are to be sought in the tow-net near the 
surface of the sea, and are often very quaint in form. The 
study of the development is beyond our scope, but this 
chapter would be incomplete if it did not mention the fact 
that not only are larvae and adults very unlike one another, 
but that the former are converted into the latter by a 
remarkable process of metamorphosis. Further, on account 
of their marine habit, and the abundance of lime contained 
in the tissues, the Echinoderms are abundantly represented 
as fossils, and their geological history is in consequence 
better known than that of most animals. 






(1) The Asteroids, or Starfishes. Body star-shaped, with stout 
arms containing prolongations of the digestive and reproductive organs, 
and open anibulacral grooves. 

'Spines small, nu- 
merous, with 
one row down 
centre of arms 
A. nibens. 
Spines large, not 
very numerous, 
arranged in 
three to five 
rows A. gla- 

groove narrow, 
rows of spines 
H. sanguino- 

Rays five, rarely 

Tube-feet in four v 
rows, skeleton 
reticulate, its 
small plates 
bearing sim- 
ple spines. 

Tube-feet in two 
rows, skeleton 
meshes bear- 
ing clusters of 
small spines. 
No pedicel- 

Henricia . 

Rays more thanj 

grooves fring- 
ed by com 
like spines 

rRays 11 - 14, 
colour red or 

/Dorsal spines purplish red, 

brush - like, dorsal spines in 

tufts S. pap- 
Solaster . .1 posus. 

Rays 9-11, colour 
usually purple, 
dorsal spines 
much crowded 
S. endeca. 

(2) The Ophiuroids, or Brittle-Stars. Body star-shaped, arms long 
and slender without prolongations of the digestive or reproductive 
organs ; no distinct anibulacral groove. 


1, arm spines f Arms fragile and 

notched, ^ G \.0nhiothrix \ long ' s P ines 

with spines f * 'j long and glassy 

and distinct [ 0. fragilis. 
radials . ./ 

Tooth - papillae 
(see p. 131) 
present . 



The Ophiuroidsj or Brittle-Stars. continued. 

r Arms inserted 
on ventral sur- 
face; few- 

^Spines on arms 
stout, not long, 
extra plates on 
arms, which 
are wide and 
flat Ophio- 
pJwlis . 

Three mouth -pa- 
pillae, seven 
spines at sides 
of arms, radials 
indistinct 0. 

No tooth-papil- 
Ise, mouth-pa-, 
pillae .present, 
spines smooth 

mouth - papil- 

Spines short and^ 
small, arms 
with distinct 
radials Am- 
. phiura . 

Three mouth-pa- 
pillae, three or 
- four fine spines 
at sides of arms 
A. elegans. 

Arm notches with 

more than 25 

Arms inserted 1 i i 
_ . i spinose Dursai 

spines 0. cili- 

rous mouth- 1 S extend to 

Arm notches with 

rjamllse edge of disc 

less than 20 

\. uprtiura. 

spines 0. al- 


(3) The Echinoids, or Sea-Urchins. Body more or less rounded, 
covered by spines, test composed of plates arranged in regular rows. 

/Test well rounded, 
Body spherical, anus spines pinkish or 

opposite mouth, five 

regular double rows 
of ambulacral plates, 
Aristotle's lantern 
present . 

Body heart - shaped, 
anus posterior, am-^ 
bulacral areas peta- 
loid, no lantern 


white E. escu- 

Test depressed, spines 
purple-tipped E. 

c, . , ,, f [ Colour golden when 

Spines and therefore fresh * nteriortube _ 

tubercles,nearlyequalj f | n ft ye ._ 


Some spines, and there- 

K Colour purple S. 

fore some tubercles, 
larger than rest 
Spatangus . . - 

(4) The Holothurians, or Sea-Cucumbers. Body more or less 
elongated, without well-developed skeleton. Mouth with a fringe of 

Tube - feetfTentacles ton, 

present . ^ edCucumana . . 

JTentacleswithsimplelateran T d t d 
Tube - feet! branchesordigits, anchors ' 

absent .| and^hor-plates present 




Generally speaking, the North Sea is poor in Echinoderms as 
compared with other parts of our area, bub this is to some extent 
compensated for by the great abundance of certain common species 
on its shores. Thus, the common sun-star, Henricia sanguinolenta, 
and the common starfish (Asterias rubens) are probably commoner 
between tide-marks on the North-east Coast than on the South and 
West. On parts of the South and West Coasts the spiny starfish 
(Asterias glacialis) is to be found not uncommonly between tide-marks. 
The brittle-stars mentioned are common everywhere, but on the South 
the handsome yellow Ophiocoma nigra may also be expected between 
tide-marks. In regard to the sea-urchins, those mentioned in the 
text are widely distributed, but so far as my experience goes, Echinus 
miliaris reaches a much larger size between tide-marks on the West 
Coast than on the East. On the South and West sea-cucumbers are 
much more likely to be found between tide-marks than on the East. 
In addition to Cucumaria ladea, other species, such as G. pentades, 
occur there. 


General characters of Crustacea Structure of prawn, lobster, and 
crab Classification of Decapod Crustacea Swimming and creeping 
forms Common British shrimps and prawns. 

IJS" this chapter we have to consider one of the most inter- 
esting classes in the animal kingdom, interesting alike on 
account of the beauty of form and colour, of the structure 
and the habits. The class Crustacea is a very large one, 
and embraces a great variety of animals adapted for many 
different habitats and modes of life. Like the insects on 
land, the Crustacea seem to display every possible modifica- 
tion of parts; if they are less popular than insects it is 
certainly not because they display fewer points of interest 
or less beauty. 

They resemble insects in being clothed in an envelope of 
chitin, which invests the whole body, and is inturned to 
line part of the alimentary canal and to form the tendons of 
the muscles. This chitinous coat gives great definiteness 
of form the Crustacea never exhibit the variability of 
shape which often makes the study of soft-skinned animals 
so difficult; it has also such an intimate connection with 
the internal organs that the external appearance may be 
used as a test of affinity. In this respect the Crustacea, 
or indeed the Arthropoda in general, differ markedly from 
Molluscs. The shell of the latter has no very intimate 
connection with the internal organs, it in itself yields little 
information as to the anatomy of the contained animal. 
In consequence, the structure and affinities of Molluscs can 
be made out by dissection alone, and dissection, moreover, 
which is often tedious and difficult even for trained fingers. 




On the other hand, the structure of the external parts of a 
Crustacean in the general case determines the systematic 
position of the animal, and the examination of such external 
parts requires more care than anatomical skill in the strict 
sense. The Crustacea are therefore par excellence the class 
for the novice, the one above all others in which he can 
hope to walk by sight and not by faith. 

In studying the Crustacea it is convenient to begin with 
the higher forms, which are usually of such size as to make 
observation easy. To acquire a general knowledge of the 
structure, we may compare three common forms a prawn, 
a lobster, and a crab. The common prawn (Palcemon serratus), 
a beautiful little creature about four inches long, is not likely 
to be found on the East Coast, but a smaller species (P. 
squilla) is not uncommon in rock pools, and is large enough 
for our purpose. The hump-backed Esop prawn (Pandalus 

annulicornis) may 
also be found far 
out on the rocks; 
while, failing all 
three, the common 
shrimp may be sub- 
stituted. As to the 
second specimen, 
the lobsters really 
lie somewhat out- 
side our province, 
but the Norway 
lobster (Nephrops 
norvegicus) can be 
purchased very cheaply at a fishmonger's, and is admirably 
adapted for the study of many Crustacean characters. Those 
who do not find it available will probably be able to obtain 
the fresh-water crayfish, or that somewhat costly luxury 
the true lobster. Add to your specimens the common shore 
crab or the edible crab, and you are prepared for the study 
of the characters of the Crustacea. 

Place your three specimens prawn or shrimp, lobster or 
crayfish, and crab side by side, and note first their common 
characters. All three can be divided into two similar parts 
by a line down the middle of the body that is, all are 

FIG. 47. A common prawn (Palcemon squilla). 


bilaterally symmetrical. All are invested with a firm 
cuticle of chitin, are furnished with jointed hollow limbs, 
and in each case the body consists of a series of similar 
parts or segments, least obvious in the crab. Because of 
these characters all are Arthropods. Further, we include 
them in the class Crustacea because all have two pairs of 
feelers (antennae), a shell containing carbonate of lime, and 
all breathe by gills. The last-named structures may be 
readily seen in prawn and lobster by gently raising the 

FIG. 48. Common lobster (Homarus vulgaris). 

large flaps at the sides of the body in the anterior region. 
Beneath these lie delicate structures, shaped like bottle- 
brushes, and closely connected with the limbs. In the crab 
the gills are so well protected by the shell as not to be seen 
without dissection. 

Looking now at our specimens in somewhat greater detail 
we see that the prawn and lobster or crayfish resemble one 
another in that in both the body consists of an anterior, not 


obviously segmented region, covered by a shield, and a tail 
made up of a succession of similar parts. The anterior 
region we call the cephalothorax for it is made of head and 
thorax united the posterior, the abdomen or tail. The 
cephalothorax, or united head and body, contains the greater 
part of the organs of the body ; the tail is mainly filled up 
by powerful muscles (flesh), and in both prawn and lobster 
serves as an organ of locomotion. The crab, on the other 
hand, differs markedly from the other two in that it appears 
to have no tail. Turn your crab over on its back, however, 
and you will have no difficulty in seeing that it has really a 

FIG. 49. Shore crab (Carcinus mcenas). 

true tail, reduced in size, useless for locomotion, without 
muscles, and habitually carried reflexed on the body, but a 
tail none the less. The body of the crab, no less than that 
of prawn or lobster, consists of cephalothorax and abdomen, 
but the proportions of the two parts differ markedly. In 
consequence of this marked difference the order of Crustacea 
to which the three forms belong (Decapoda, or forms with 
ten legs) is often divided into long-tailed forms, such as 
shrimp, prawn, and lobster, and short- tailed forms, such as 

Although there is considerable resemblance between 
prawn and lobster as contrasted with crab, a little more 


detailed observation will convince you that in some respects 
the crab and lobster resemble one another closely and differ 
from the prawn. Thus the body of the latter is laterally 
compressed; its dorsal shield is prolonged forward into a 
great beak, or rostrum, which is narrow from side to side ; 
its ten legs are placed very near the mid-ventral line, and 
are very slender as compared with the weight of the 
body ; its powerful tail is furnished not only with tail fins, 
but bears also five other pairs of well-developed oar-like 
swimmerets. clearly shown in the figure. In brief, it is 
essentially a swimming animal, capable of supporting itself 
in mid-water by gentle rowing movements, or darting back- 
wards by powerful tail strokes. On the other hand, in crab 
and tobster the body is more or less compressed from above 
downwards; the rostrum, when present, is broad from side 
to side ; the legs are very well developed, and are divided 
into an anterior pair of forceps, which are weapons of 
offence and defence, and four pairs of walking legs, which 
are not attached at the middle of the body, but at such a 
position as to most readily support the weight of the 
body. In the lobster the tail is a powerful organ, but the 
swimmerets, except the last one, are not well developed. 
In the crab, as already seen, the tail is greatly reduced. 
In other words, crab and lobster are typically creeping 
animals, adapted for life on the bottom. The lobster re- 
tains, in addition, the power of swiftly darting backwards 
by the flexing of the tail, and therefore retains also the 
long feelers, movable exposed eyes, and some other charac- 
ters in common with the prawn; but the crab can only 
crawl, and is adapted throughout for life among stones and 

If you have observed these points in your intact speci- 
mens, then the next thing to be done is to take them to 
pieces. Living specimens are best killed by dropping them 
into very hot water for a few minutes. Of the three, the 
Norway lobster, or crayfish, is the easiest to dissect. For 
full details as to method, reference should be made to one 
of the ordinary biological text-books, such as Marshall and 
Hurst's Practical Zoology, or Thomson's Outlines of Zoology; 
here we can only consider those points which are of im- 
portance in our systematic survey. 


Notice, first, that the shield, or carapace, is prolonged 
forward between the eyes into the strong spiny beak, that 
in its anterior region it has a strongly marked groove which 
runs forwards to end near the outer side of the second pair 
of antennae, or feelers, and that it is prolonged at either 
side into the large gill-covers which protect the lateral gills. 
Besides the distinct groove, other dorsal markings divide 
the carapace more or less distinctly into regions. Of these, 
the most distinct are the gastric region immediately behind 
the rostrum, with a hepatic region at either side. Behind it 
is the cardiac region, which has at either side the large 
branchial regions. The regions are named after the organs 
which lie beneath them, and are indicated in the figure of 
the crab. The tail differs considerably from the anterior 
part of the body, for it consists of six similar rings, each 
carrying a pair of appendages, and an end piece, or telson, 
without appendages. Each ring consists of an arched 
dorsal portion, two projecting side flaps, a socket for the 
limb, and a ventral bar with a spine in the middle. 
Typically in the Crustacea the whole body should consist 
of such rings, but in the three specimens chosen the 
anterior thirteen rings are fused together, and are over- 
lapped by the great shield, which has grown backwards 
from the anterior segments. The function of this shield, 
as already seen, is to protect the viscera and gills. 

Perhaps at this point it may be well to interpolate a note 
on terminology. To the beginner it may seem that the 
greatest drawback to the study of Natural History is the 
number of technical terms used to describe even the simplest 
animal, and that the number of these terms has been need- 
lessly multiplied. This last is perhaps a point which might 
be debated, but we may notice that the use of technical 
terms is justified on two grounds. First, they have perfectly 
definite meanings, which cannot be said of the majority of 
their Anglo-Saxon equivalents; and, second, they express 
concisely, and in a word, a meaning which it would require 
an English phrase to make clear. The term Decapod 
Crustacea, for example, gives a naturalist a perfectly clear 
idea of a group of animals which would in English be 
inadequately described as "hard-coated animals with ten 
legs." Although, therefore, an effort has been made to 


keep down the number of technical terms in this book so 
far as possible, they have been used whenever clearness and 
conciseness would be sacrificed by their absence. Among 
the Crustacea especially, a certain number of such terms 
seem absolutely necessary, if the relation between the 
different forms is to be made clear. 

Returning to the study of the crayfish, it is obvious that 
if the cephalothorax contains thirteen united segments, and 
the tail six free ones, and each of these segments bears a 
pair of appendages, then there must be nineteen pairs of 
appendages, apart from the tail-piece, or telson. These 
nineteen pairs of appendages are most easily studied by 
beginning at the posterior end, removing the appendages of 
one side successively, and laying them out in order. 

In the following list they are for convenience described 
from before backwards : 

(1) First antennae, or antennules, consisting each of a 
stalk, or peduncle, and two short whips, or flagella. 

(2) Second antennae, or antennae proper, consisting each 
of a peduncle, bearing an outer broad flat scale, or squame, 
and a long inner flagellum. 

(3) The mandibles, hard, toothed plates, close to the 

(4) First pair of maxittce, or jaws, small, delicate, and 
probably functionless. 

(5) Second pair of maxillae, also very delicate, but 
furnished with a plate the baler of much importance 
in respiration. 

(6, 7, 8) Three pairs of foot-jaws, or maxillipedes, con- 
sisting of a basal piece and an inner and an outer branch. 
The inner branch, especially in the third maxillipede, is 
more or less leg-like (see b in Fig. 50). 

(9) The great forceps, or chelipedes. 

(10, 11, 12, 13) The four pairs of walking legs, all with 
seven joints. (It is because of the presence of these five 
pairs of "legs" (appendages 9-13) that the three types are 
included in the order Decapoda.) 

(14, 15, 16, 17, 18) The small swimmerets, typically 
consisting of a basal piece and an outer and an inner 
branch, but the first two pairs are more or less modified in 
the male. 


(19) The last pair of swimmerets, or uropods, large and 
powerful, with the telson constituting the tail-fan. 

Besides these nineteen pairs of appendages, we have the 
large, compound, stalked eyes, which consist of a number of 
eye-elements compacted together. 

As the thoracic appendages are removed, it will be found 
that some of the gills come away with them. Break away 
the gill-cover at the other side of the specimen you are 
dissecting, and you will see that the gills lie in a chamber 
opening freely to the surrounding water in front and behind. 
In order that the lobster may breathe, it is necessary that 
these gills be continually washed with fresh water. When 
the lobster is swimming, or in a typical swimming Crustacean 
like the prawn, this is accomplished by the movement of 
the whole animal through the water ; but in a state of rest 
the lobster would asphyxiate were it not that its second 
maxillae are in constant movement, and by baling the water 
out in front cause a constant current to pass in at the 
posterior end of the gill-cover. This is readily seen in a 
living Crustacean by suspending fine particles in the water 
in which it is living, and is a point of great importance. 
It is an advantage to the Crustacean to have its delicate 
breathing organs protected by a gill-cover, but this advantage 
brings with it the necessity for a mechanical means for 
constantly renewing the water beneath the cover. In crabs 
the protection of the gills is more efficiently provided for 
than even in prawn and lobster, and they are less actively 
motile animals than either. The result is that the renewal 
of the water under the gill-cover of the crab has to be 
provided for by active means, and many of the striking 
peculiarities of the crab are associated with this fact. 

If you can obtain more than one specimen of Nephrops, 
it is a good plan to dissect one, and then use the experience 
gained to make a permanent preparation of another, laying 
out the parts in order on a sheet of card or glass. The 
flesh should be removed from the larger appendages, the 
rings of the abdomen separated and cleaned, and the great 
shield removed entire. During the process of preparation 
you will find two skeletal parts which we have not yet 
noticed the so-called internal skeleton of the thorax, and 
the gizzard. The former is a very complex structure, formed 


in part by the fusion of the ventral and lateral elements of 
the thoracic segments, and in part by additional structures. 
It will be recollected that the cephalothorax or anterior 
region is as truly formed of segments as the abdomen, but 
that it is overlapped by the great shield which has developed 
from the anterior segments. In consequence, the skeleton 
of the overlapped segments has in part disappeared, in part 
developed into the apparently internal skeleton which pro- 
tects and covers the nerve cord. 

The gizzard is that part called by cooks " the lady in the 
lobster," and it contains firm limy bars bearing teeth which 
clash against one another and grind the food. It should be 
washed out and split open to see the teeth and bars. 

When all the parts of the crayfish are cleaned and laid 
out in this way, they can be left to dry, and the whole will 
be found exceedingly useful for reference afterwards. 

The next point is to compare the crayfish in detail with 
the prawn. We have already noticed the similarity in 
broad outline, but there are some interesting differences 
in detail. Notice in the prawn the laterally compressed 
beak, as compared with the flattened one of Nephrops; 
this is of course associated with that difference in the shape 
of the body which we have already noticed. The most 
striking differences are, however, to be found in the nature 
of the appendages. The filaments of the antennules are 
long, and, if the prawn be a Palcemon, each antennule will 
bear three instead of the two of Nephrops. This is a 
point of minor importance, however, as compared with the 
structure of the antenna. They will be found to have a 
relatively enormous squame, or scale, as contrasted with the 
small one of Nephrops; while the crab, again, has no trace of 
antennal scale at all. The scale is a heritage from far-off 
swimming ancestors, and diminishes in size as the swimming 
power diminishes. 

The maxillipedes of the prawn (Palcemon) resemble 
generally those of the crayfish, but the walking legs differ 
markedly, as already noticed. They are very long and 
slender, the first pair especially being so slender as to 
resemble feelers rather than legs ; they are habitually carried 
folded upon themselves, and end in minute forceps. The 
next pair are larger and stronger and also end in forceps, 


and the last three pairs are simple, ending in sharp claws. 
The legs will be found to differ a little in the different 
kinds of prawns, but are always very different from those of 
lobster or crayfish. 

The tail is remarkable for the great development of the 
five anterior pairs of swimmerets, as compared with those of 
Nephrops. Most of the above points should be readily 
made out from the accompanying figure. 

If from the prawn we turn to the crab, we find well- 
marked differences from both prawn and lobster. It is only 
possible to point out some of these differences. The carapace 
has been, as it were, strongly flattened out, and in the 
process the rostrum has disappeared, and the relative posi- 
tion of eyes, antennae, and antennules altered enormously. 
Prawn and lobster swim rapidly, and as they swim their 
long feelers, their freely movable eyes, make them fully 
aware of their surroundings, while their vigorous tail strokes 
remove them instantly from the dangers of which those 
keen sense-organs give them notice. But the crab only 
moves slowly ; it only requires to be made aware of its 
immediate surroundings ; it is often content to offer a 
passive resistance to foes. Therefore its antennae are 
shorter, less prominent, and capable of more or less com- 
plete retraction ; the eyes are sunk in orbits which protect 
them from harm even if they also limit the field of vision. 
The gills are more efficiently protected, and the parts about 
the mouth are much modified. Again, while in prawn and 
lobster more than one pair of legs bears terminal forceps, in 
the crab it is only the first pair which is thus modified ; the 
others are simply pointed, and used for locomotion only. 

Let us look now at these points in a little more detail. 
The carapace, or shield, of the crab is in essence similar to 
that of prawn and lobster, and shows a similar division into 
regions, but, besides being flattened and expanded laterally, 
it is inturned at the anterior and lateral margins. This is 
readily seen, and the change may be expressed in a rough 
metaphor by saying that a crab's shield is like that of a 
lobster which has been crushed flat. As a result in part of 
this crushing, we find that the lateral area which in the 
lobster or crayfish forms the vertical gill-cover has here 
become horizontal, and is separated from the remainder of 


the shield by a distinct movable suture The inturning of 
the carapace in the frontal region has, as it were, carried in 
with it the insertion of the antennules, so that we no longer 
find these on the dorsal surface, but placed in little pits 
beneath the margin of the shield. They are very short, 
consist of one filament only, and are carried doubled up 
when not in use. The eyes, instead of lying above the 
antennules, are shifted outwards, and lie in somewhat elon- 
gated sockets, or orbits, into which they can be completely 
retracted. The very short antennae, without trace of scale, 
are squeezed in between orbits and antennules. Their 
peduncles are very short, the basal joints being lost in a 
triangular plate which lies in front of the mouth. 

FIG. 50. Maxillipedes, or foot-jaws, of edible crab (A) and lobster (B). In 
each figure, g is the gill, s the gill separator, ex the outer branch, en the 
inner branch. 

On the minor peculiarities of the mouth parts we need not 
dwell. It is sufficient to note that they are more crowded 
and overlap one another more completely than the similar 
parts in the lobster. The point which is especially worth 
notice, however, is the character of the third maxillipede-s. 
As is seen in the figure, in the lobster these are distinctly 
leg-like, but differ from the walking legs proper in that they 
have a slender outer branch in addition to and arising from 
the same base as the leg-like inner branch. The third 
maxillipede of the crab has in essence the same structure, 


but its inner branch, instead of being leg-like, is converted 
into a flattened plate, covering over all the anterior ap- 
pendages, and closing the anterior opening of the gill- 
chamber. In Mysis, a simpler Crustacean than any of those 
yet considered, all the eight thoracic appendages are similar, 
all consist of a basal piece with a leg-like inner branch and 
a slender outer branch. In prawn and lobster the anterior 
three only retain this " biramose," or two-branched structure, 
but they otherwise generally resemble the walking legs 
proper, this being especially true of the third. In the crab 
these three maxillipedes are fundamentally modified to sub- 
serve functions connected with respiration and mastication, 
and the structural gap between them and the true legs 
attains its maximum. It is facts of this kind which induce 
morphologists to regard the crab as more specialised than 
the lobster, though it has lost some of the powers which 
the latter possesses. 

The legs of the crab will be found to display many in- 
teresting peculiarities. The first pair are always the largest, 
and constitute the main weapons of offence and defence. 
Their shape and markings are often characteristic of the 
species, and in many cases they fit in repose very closely to 
the margin of the carapace, a point we shall consider later. 
Near their base is the slit through which water enters the 
gill-chamber ; a carapace which has been removed with 
sufficient care not to damage the movable gill-cover will 
show a notch at this point. The remaining four pairs of 
legs never bear forceps, and differ markedly in the shore 
crab and the edible crab. They always form the organs of 
locomotion, and are inserted laterally so as to form an 
efficient support for the body. The last pair arises some- 
what dorsally. An interesting point about them is that all 
are made of six pieces only. In the lobster the chelipeds, 
or great claws, have six joints, the other. legs seven. A 
careful comparison will show that this is due to the fact 
that in the great claws segments two and three, counting 
from the base, are fused together, the line of junction being 
clearly marked. When a lobster throws off its great claws, 
as it often does when frightened or molested, separation 
takes place at this junction line. A lobster only possesses 
the power of throwing off its great claws, and not the other 


legs ; but in a crab where all the legs display this peculiar 
modification, any one of them may be thrown off. Separa- 
tion always takes place at the one point, and the fusion 
of segments is to be regarded as a special adaptation to^ 
facilitate this autotomy or self-mutilation. In this respect 
also, therefore, the crab shows an increase of specialisation 
as compared with the lobster. 

Turning now to the ventral surface of our crab we find 
that, as already noticed, the rudimentary abdomen is flexed, 
and lies along the ventral surface of the thorax. But it is 
much narrower than the thorax, and the lateral insertion of 
the legs exposes the ventral surface of the latter much more 
fully than in prawn or lobster ;. so we find in the first place 
that this ventral surface is in the crab very firm and hard 
completely calcified. Bend the abdomen gently backwards, 
and you will see that the thorax has a deep ventral groove 
in which the abdomen habitually lies. The abdomen itself 
bears rudiments of appendages, but these are much reduced. 
Let us recall for a moment the abdominal appendages of 
prawn and lobster or crayfish. In the prawn there are six 
pairs of functional swimmerets, the last pair being much 
the largest. In the lobster the first pair is rudimentary in 
the female, and curiously modified in the male ; the next 
four pairs are small and of little use in swimming, though 
in the'female they carry the eggs ; the last pair is large, and 
forms with the telson the powerful tail fan. In the crab, 
with the reduction of the abdomen, we have the total 
suppression of this tail fan, and the development of the 
others varies in the two sexes. In the male the two 
anterior pairs only are present, and are much modified ; in 
the female four pairs are present; they are long and 
delicate, and furnished with numerous hairs. As in the 
lobster they are used for carrying the eggs. The number 
of segments in the abdomen of crabs tends to be reduced, 
more especially in the males. 

We have thus briefly revised the main points of external 
structure in three types of Decapods, and may look for a 
little at the order in general. We have already noticed the 
striking resemblances between prawn and lobster which 
have led naturalists to classify them together as Macrura, 
or long-tails, in contradistinction to the short-tailed crabs, 


and have also mentioned that other possible division which 
places the prawn as a typically swimming animal, in oppo- 
sition to the creeping crab and lobster. Accepting this last 
division, we find that the swimming Decapods, or Natantia, 
have the following characteristics in common : The body is 
always more or less compressed, as is also the rostrum. The 
abdomen is well developed, its first segment is not markedly 
smaller than the rest, but the second is usually very well 
developed. The antennae have a five-jointed peduncle and 
a large scale. The thoracic limbs are slender, are all seven- 
jointed, and only in rare cases is the first better developed 
than the others. Usually more than one pair are furnished 
with chelae, and the penultimate segment is attached to the 
antepenultimate by one fixed point or fulcrum only, so that 
it swings less easily than in the Eeptant Decapods where 
there are two fixed points. The abdominal appendages are 
used for swimming. When the female carries the eggs 
about with her, which does not invariably happen, the 
second pair of swimmerets have a brood-lamella attached 
to them ; this is seen in the common prawn (Palcemonji 
Examples of Natant Decapods are shrimps and prawns, of 
which there are many kinds. Our British forms are all 
relatively small, but some tropical prawns attain a length of 
nearly a foot. Most are more or less social, and are found 
swimming in shoals. 

With these swimming Crustacea are contrasted the 
Reptantia, which have the following characters : The body 
is depressed, with a flattened rostrum, or without a rostrum. 
The abdomen is sometimes well developed and sometimes 
reduced, but its first segment is always distinctly smaller 
than the others. The peduncle of the antennae is reduced, 
and the scale is sometimes absent. The thoracic limbs are 
strongly developed, are usually six-jointed, and the first is 
the largest. The penultimate joint is attached to the ante- 
penultimate by two fulcra, or fixed points. The swimmerets 
are always more or less reduced, and in the female always 
carry the eggs. 

It might be supposed that the Reptant Crustacea could be 
sharply divided into two sets the crabs and lobsters but 
we shall find that there are many transitional forms. Our 
British forms are typically larger than shrimps and prawns, 


do not usually occur in shoals, and are often littoral. They 
show much greater diversity of structure and habit than 
the prawns, and have apparently been subjected to a much 
keener process of selection. There are in consequence few 
groups of marine animals which illustrate the problems of 
evolution more clearly, or afford more fascinating objects 
for study. One may read many books on the Doctrine of 
Descent, and yet remain untouched by the charm of the 
theory, but few persons can, I imagine, toil over the 
structure and affinities of these Crustacea without suddenly 
becoming conscious of the grandeur of the generalisation, 
of its power of unifying what previously seemed insignificant 

We shall now proceed to consider successively typical 
British representatives of the Decapoda. 

The members of the sub-order Natantia all fall into the 
family Caridida3 which has the characters of the sub-order. 

A large number of genera are included in this family, 
but it is only possible for us to consider a few of them. 
We may repeat, however, that the great interest of these 
forms is that on the one hand they show close relationship 
to the next lower order of Crustacea, the Schizopoda, and 
on the other they markedly resemble the Eeptant Decapods. 
This is especially true of the lowest forms, notably the 
curious shrimp Peneus, which seems to stand half-way 
between the Schizopods and the crayfish and lobster. This 
shrimp is, however, a Mediterranean form, and only occurs 
very rarely in the South-west of Britain. 

It is worth while to notice here that there are a number 
of interesting Crustacea which are rare in Britain, and are 
confined to the South and West. Such forms are almost 
always Mediterranean species, and we may say generally 
that our littoral fauna is of two types, the Mediterranean 
type, which predominates on the South and West, and the 
Northern, or Scandinavian type, which predominates on the 
North and East. In addition, on the West we find certain 
peculiar animals which are not truly members of our fauna, 
but are brought, more or less passively, by the Gulf Stream. 
Animals which occur all round our coasts may generally be 
assumed to be common to the Scandinavian and Mediter- 
ranean faunas, while our East Coast rarities are Scandinavian 


types. The differences between East and West are often 
exceedingly striking, and cannot fail, for example, to 
astonish anyone passing from the Firth of Forth to the 
Firth of Clyde. One must suppose that in many cases it 
is the warm currents which wash our western shores which 
have carried the Mediterranean animals northwards, but the 
fact that the shore on the West Coast is generally more 
rocky than the East, and is often fringed by deeper water, 
has no doubt also much influence. 

As Peneus is too rare to be described here, the first of 
the Carididaa which we shall describe is the common prawn 
(Palcemon serratus). This is the largest of our prawns, and 
on certain parts of the coast, together with the much smaller 
P. squilla, is the object of an important fishery. Both turn 
bright red when boiled, and are so popularly distinguished 
from the common shrimp, which merely turns a brownish 
pink. A species of Palcemon may be instantly recognised 
by the fact that each antennule bears three feelers, of which 
two at least are very long, and by the fact that both the 
first two pairs of feet are furnished with distinct forceps, 
the second being much larger than the first. As other 
characters we may note the large rostrum, which is strongly 
toothed, and projects far forward between the eyes; the 
position of the antennae, which are inserted beneath, and 
only slightly to the outer side of the antennules ; and the 
other characters incidentally noticed in the description of 
the prawn. 

As to the species, on the East Coast P. serratus is not 
very likely to be seen except in a fishmonger's, but on 
certain parts of the coast young forms are not infrequent 
between tide-marks. The colour is greyish, with spots and 
markings of brown and red. The rostrum is very long, 
longer than the large scale of the antennae, and turns up at 
the point, forming a cruel-looking weapon. It has eight or 
nine teeth above, placed near the base, and five or six 
beneath. The filaments of the antenna?, and two of those 
of the antennules, are very long, so that the trailing threads 
are very conspicuous objects. The strong abdomen, with 
its well-developed appendages, has already been noticed. 

The other common species of prawn (P. squilla, Fig. 47) 
is also typically an inhabitant of deep water, but it occurs 


not infrequently in rock pools, especially at low tides. Such 
specimens are usually females carrying eggs. The colour is 
greyish white with touches of brighter colour. The differ- 
ences from the preceding species are not very well marked, 
especially if only small specimens of P. serratus are avail- 
able ; but it will be noticed that in the present form the 
rostrum is nearly straight, and has seven or eight teeth 
above, and only three beneath. The rostrum is also rela- 
tively shorter, and it does not usually exceed the length of 
the antennal scale. The whole prawn does not exceed two 
inches in length. Either of these prawns will repay careful 
study, for which their relatively large size peculiarly fits 
them. There are some other British species of Palcemon, 
but these are rare, and need not be considered here. 

The next form to be considered is the Esop prawn, or 
shrimp (Panddlus annulicornis), which, like the true prawns, 
is typically an inhabitant of deep water, but is occasionally 
met with in rock pools. It is of much the same size as 
Palcemon squilla, which it resembles not a little, but is of 
a somewhat brighter colour, the long antenna in particular 
being in life beautifully ringed with scarlet. Like most of 
the smaller Crustacea, it loses most of its beauty at death, 
owing to the disappearance of the delicate transparency of 
tint. In general shape and appearance the Esop prawn 
resembles the true prawns, but can be distinguished from 
them by the humped back, and by the different character of 
the legs and antennules. In these respects it resembles the 
next genus, Hippolyte, much more closely than Palcemon, 
and the student should not fail to notice how closely the 
three genera resemble one another, and how the Esop prawn 
stands midway between the other two. 

As to the detailed characters of Pandalus, notice that the 
hump-backed appearance is due to the fact that the third 
abdominal segment is pouch-like, being much longer on 
the upper than the lower surface, so that the tail cannot be 
completely straightened. Further, the antennules bear two 
filaments only instead of three as in Palcemon, and one of 
these is thickened and curiously curved. Again, the first 
pair of legs end in exceedingly minute chela?, and the 
second are slender, thread-like, and of unequal size. The 
filiform appearance is in part produced by the fact that the 


antepenultimate segment, which morphologists call the wrist, 
or carpopodite, is broken up into a number of joints, so that 
it resembles a whip in appearance. 

The Esop prawn may be found not infrequently among 
the " prawns " brought to market as food. 

Much smaller than Pandalus or Palcemon are the various 
species of Hippolyte, which are common on our shores, but 
not being large enough for use as food are not well known, 
and have no common name. The commonest form is 
H. varians, a beautiful little creature, about three-quarters 
of an inch in length, and showing much variation in colour. 
It is typically green, but among dark weed brown varieties 
are common, and in pools lined with Red Algse the tint 
may be distinctly reddish. In common with the other 
members of its genus it has the following characters : Like 
Pandalus, it has a hump-back, which is due to the same 
cause ; the antennules generally resemble those of Pandalus, 
but the thicker filament is much curved, and furnished with 
numerous bristles ; both filaments are short. It differs from 
Pandalus in the nature of the first pair of legs, for these 
are short, equal, and distinctly chelate ; the second and re- 
maining pairs closely resemble the corresponding appendages 
in Pandalus. There is usually a well-developed rostrum, 
and it is the condition of this structure which is chiefly 
relied on in the distinction of species. In //. varians it is 
straight, furnished above with one spine near the base, and 
one near the apex, beneath it is sharply keeled, and bears 
two spines. The inner filament of the antennules is only 
very slightly curved. These characters should be sufficient 
to distinguish this species, which is the only one which can 
justly be described as common in the littoral zone of the 
East Coast. On the West, however, and especially the 
South-west, another species is sometimes extraordinarily 
abundant. This is H. cranchii, which in certain parts of 
the Devonshire coast seems to occur in every rock pool. 
In life it is of a delicate green colour, with the appendages 
ringed with pale blue ; but the green colour is very fugitive 
after death. It reaches about the same length as the pre- 
ceding species, but the greater breadth of the thorax gives 
it a much more robust appearance. The rostrum is short, 
furnished with three teeth above, besides the two in which 


it ends. Beneath there are no teeth. The two species show 
very, little resemblance to one another. The other species 
of Hippolyte being mostly rare or inhabitants of deep water 
are beyond our scope. 

Very little observation will convince the student that the 
three genera just described resemble one another very 
closely, and no difficulty will be found. in drawing up a list 
of their common characters. All differ somewhat markedly 
from the next genus we have to consider that which 
includes the common shrimp (Crangon vulgaris). Of this 
abundant and familiar form it is always easy to obtain 
specimens. In the tidal streams flowing between the rocks, 
near the mouths of rivers, in sandy pools, wherever there is 
abundant sand one may be almost sure of finding this 
ubiquitous form, darting rapidly hither and thither, or 
burying itself deep in the sand. In life, as everyone knows, 
shrimps are sand-coloured, but examination with a lens will 
show you that although the general tint be dull, the shrimp 
is minutely speckled with brilliant red-brown spots of singu- 
larly beautiful shape. When boiled, the true shrimp does 
not become bright red, as do many of its allies, but merely 
pinkish brown, and on this account is often called the 
brown shrimp as a distinction from the prawns. The 
common shrimp is the only species of its genus which can 
be justly described as common on our shores, but as other 
species do occur, especially on the West, we may take the 
characters of the genus first, before mentioning those 
peculiar to C. vulgaris. All the true shrimps differ from 
the prawns in the following characters : the carapace is 
somewhat depressed instead of being flattened from side to 
side, and the rostrum is rudimentary ; the abdomen is long 
and very strong; the antennae are placed at the outer side of 
the antennules, and not beneath them ; the antennal scale is 
large, and the filaments of the antennules similar. The 
legs are peculiar, especially the first pair, which are short 
and stout, and exhibit the condition described as sub- 
chelate. It will have been noticed that when hitherto 
appendages have been described as ending in chelae, or 
forceps, the chela3 have all been of the same structure. 
That is to say, in each case the last joint ("movable 
finger") has worked against an immovable prolongation of 


tKe preceding joint, which formed the other half of the 
forceps. In the shrimp the prolongation of the penultimate 
joint is very minute, and the last joint is bent down sharply 
upon the preceding joint ; this condition is described as sub- 
chelate. The next pair of legs in the shrimp are very 
slender and end in chelae ; the remaining legs end in simple 

The common shrimp can be recognised by the following 
special characters. The carapace has three spines only, a 
median and two lateral; the abdomen is perfectly smooth, 
and regularly marked with brown spots. It is the largest 
British member of its genus, and reaches a length of two 
and a half inches. 

The great size of the antennal scales is a very obvious 
feature of the shrimp, and it is interesting to note that in 
burying itself it first makes an excavation by rapid move- 
ments of the legs, and then completes the process by 
shovelling sand over the body by means of the antennal 
scales. It is a matter of common observation how complete 
the burying process is. 

This completes the description of the common types of 
Natant Decapods. It should be clearly understood that 
there are other British genera besides those described, but 
specimens of them are rare in Britain, and have been 
omitted. The descriptions given above will be sufficient to 
make plain the general characters of these Crustacea as con- 
trasted with the creeping forms next to be described. 




DECAPODA (Crustacea with\ I. NATANTIA (swimming forms). 
ten pairs of legs) . . f II. REPTANTIA (creeping forms). 

I. NATANTIA. Family Carididne (shrimps and prawns). 
Body depressed, rostrum" 
rudimentary . 

Body compressed, 
well developed 

\Crangon (common shrimp). 

Antennules with 
filaments . 

Antennules with two fi\B.-\Pandaltis. 
ments . . .) Hip^olyte. 

Filaments of antenmiles^ 

long and sub-equal, \ Panda iu<* 
first pair of legs very K ' 
long and slender . J 

short, one thick and 
curved, the other 
slender and straight, 
first pair of legs short 
and distinctly che- 


f Rostrum curved, with eight 
or nine teeth above, and 
five or six beneath P. 

Rostrum straight, with 
seven or eight teeth 
above, and three beneath 
P. squilla. 

Rostrum very long, curved 
upwards, anterior half 
without spines, except for 
a very small one near the 
apex P. annulicornis. 

Rostrum with two spines 
above and two below 
//. varians. 

Rostrum with three spines 
above, and a terminal 
notch, none below H. 


Little need be said on this point in addition to what is noted in the 
text. Prawns, generally speaking, are commoner on the South and 
West than on the North and East, and Palcemon serratus, at least, is 
not likely to be found on the East Coast. But as the prawns are better 
adapted for life in the open than between tide-marks, the occurrence 
of large specimens in the latter situation is somewhat exceptional at 
any part of the coast. The species of Hippolyte, which are small, are 
common in rock pools, H. varians in most places round the coast, 
//. cranchii on the South and West. I found it especially abundant 
in the shore pools at Lynmouth, on the coast of Devonshire. Other 
species of Hippolyte also occur. The common shrimp is found, where 
the conditions are favourable, at all parts of the coast. 



The common lobster and the Norway lobster Their distribution and 
characters Structure and habits of the spiny lobster Habits of 
Galathea Its structure and relation to the porcelain crabs The 
two common porcelain crabs Their structure and habits The 
hermit-crabs The northern stone crab and its relation to the true 
crabs The masked crab. 

Reptant Crustacea form a much larger division than 
_ the Natantia, for they include the greater number of 
the long-tailed forms together with the crabs and their 
allies. Their classification is a matter of some difficulty, 
for, as already indicated, although crabs and lobsters seem 
to be widely separated from one another, yet there are 
transitional forms which connect them together, and make a 
sharp division impossible. For our purpose it is, therefore, 
sufficient if we consider the Reptantia as divided into a 
number of families, without concerning ourselves with the 
grouping of these families into larger divisions. Following 
the same order as with the Natantia, we shall begin with 
simpler or less specialised forms those most nearly related 
to prawns and shrimps. 

The first family (As-tacidre) is that to which the cray- 
fishes proper belong. The most important members of it 
are the fresh-water crayfish (Astacus fluviatilis), a beautiful 
little creature quite outside our sphere ; the true lobster 
(Homarus vulgaris), and the Norway lobster (Neplirops 
norveyicus). The last is never found between tide-marks, 
but is at certain seasons brought to market in large numbers, 
and is included here because it is readily obtainable, and is 



so admirably suited for the study of the characters of Crus- 
tacea." It is commonly called a crayfish, but this name is 
applied indiscriminately by fishermen to all the larger long- 
tailed Crustacea except the true lobster, just as shrimp is 
applied to the smaller forms. The true lobster does occur 
between tide-marks, but only at low spring tides, when it 
may be found under overhanging rocks in the deeper pools, 
threatening the too eager naturalist with the fate which so 
nearly overtook the Mayor of Plymouth. 

The characters of the family of Astacidae may be briefly 
summarised as follows. The body is arched and slightly 
compressed from side to side. The carapace has a distinct 
cervical or neck furrow, absent in Carididae, and bears a 
well-developed rostrum. The antennal scale is relatively 
smaller than in the Carididae, and the antennae themselves 
are placed beneath the antennules, not side by side with 
them as in the higher Carididae. As in the latter, the third 
maxillipede is elongated and leg-like. Each of the first three 
legs ends in forceps, a condition paralleled in the Carididae 
in the shrimp Peneus, but the first pair are much stronger 
than the others, forming powerful weapons of offence and 
defence. The tail is long and strong, and ends in a powerful 
tail fan; the other abdominal appendages are more or less 
rudimentary, but the first pair in the male are converted 
into hardened styles. As already indicated, the Astacidae 
stand much nearer Peneus and its allies than any of the 
Natant genera which we have described in detail. We 
must suppose that the higher Natantia (true shrimps and 
prawns) and the Astacidae have both been derived, along 
different lines, from ancestral forms which resembled 

As we have seen, the three commonest forms included 
under Astacidae are the fresh-water crayfish, the true lobster, 
and the Norway lobster, and it is interesting to note that 
although they can be distinguished with perfect ease by the 
untrained eye, yet minute scrutiny does not bring to light a 
great number of marked differences : there is much general 
resemblance in structure. It is also interesting to note that 
while there are a great number of fresh-water crayfishes, 
widely distributed over the world, there are only relatively 
few species of Homarus arid Nephrops. 


The true lobster (Homarus vulgaris) is especially character- 
ised by its relatively short rostrum, which only slightly 
exceeds the peduncle of the antennae in length, and by the 
fact that this rostrum bears three teeth on each side, and 
none beneath. The very large chelipeds have the wrist 
(carpopodite) furnished with four or five large conical teeth 
on the upper border. Lobsters, as is well known, are usually 
brownish blue in colour, marbled with white ; but there is 
considerable variation in colour, full- red varieties not being 
unknown. They do not inhabit very deep water, and are 
usually caught off rocky coasts. According to the fishermen 
they are very sedentary animals, rarely venturing far from 
their particular haunts. This observation depends upon the 
fact that they have a peculiar tendency to exhibit local 
variations in colour, which is said to enable experts to name 
the locality from which particular specimens have come. 
Thick-shelled forms like the lobster cannot, of course, change 
colour according to their surroundings, as delicate forms like 
Hippolyte can ; so that if, as is generally supposed, the 
colour of the lobster has a direct relation to that of its 
environment, the adaptation must have taken place when 
the lobster was very young, or must be the result of a 
process of selection in each locality. 

Lobsters are very widely distributed around the coasts of 
Europe, and it is said that five or six millions are annually 
taken in Northern Europe alone. Whatever be the exact 
figures, there is no doubt that in most localities the in- 
cessant persecution has greatly diminished their numbers, 
and that in spite of the fact that the female lays 12,000 
eggs at a time, and carries them about with her till they 
hatch. Recently efforts have been made to protect what 
is grotesquely called the "hen-lobster in berry" that is to 
say, the female with eggs, during at least a part of the year. 

The Norway lobster, with its delicate colouring and thin, 
elaborately sculptured shell, is a much more graceful animal 
than the true lobster, and from its shape one would expect 
it to be capable of much more rapid locomotion. It never 
occurs near the shore, but lives in deep water, whence it is 
obtained by trawlers. Though typically a Norwegian species, 
it extends also in diminished numbers to the Mediterranean, 
and is the object of an extensive fishery on the east coast 


of Scotland. It is curious to note that although at certain 
seas >ns many hundreds are daily brought to market in 
Edinburgh, almost all these are males, and an egg-bearing 
female is very rarely seen ; one would therefore expect that 
a rapid diminution of numbers is less likely to occur than 
in the case of the lobster. 

In the Norway lobster the rostrum is long, slightly 
exceeding in length the peduncle or stalk of the antenna ; 
it is furnished with three teeth at either side, and is hairy 
beneath. The anterior part of the carapace (gastric region) 
is furnished with seven longitudinal rows of spines. The 
abdomen is beautifully marked, the markings being ac- 
centuated by the distribution of the fine hairs. The great 
claws differ much in shape from those of either lobster or 
crayfish, for the propodite or hand is four-sided, the margins 
being emphasised by the development of rows of spines. 
The whole limb is elongated and slender, very different 
from the broad and heavy chelipeds of Homarus. In colour 
Nephrops is a delicate orange-red with brown hairs. It is 
much smaller than the lobster, being usually seven to eight 
inches in length. Young specimens may sometimes be ob- 
tained from the trawlers, and make most charming pets. 
They live well in confinement, but have most voracious 
appetites, quite out of harmony with the fairy-like form and 
delicate colouring. In such specimens the eyes are ex- 
ceedingly conspicuous, and their peculiar "kidney" shape 
should be noticed. It is this peculiarity which gives the 
animal its scientific name (Nephrops = kidney-eyed). 

It may, perhaps, be well to note here, for the sake of 
future reference, the names given by systematists to the 
typical segments of the legs of Crustacea. Beginning at the 
outer end these are : dactylopodite, or finger ; propodite, or 
hand ; carpopodite, or wrist ; meropodite, or arm ; and less 
important, ischiopodite, basipodite, and basal coxopodite, 
seven pieces in all. 

The next family is that of the Palinuridce, including only 
one British form, the splendid rock lobster or spiny lobster 
(Palinurus vulgaris), a Mediterranean species found on the 
South and West of England and off the coasts of Ireland. 
Like many of its allies it is sometimes called a crayfish, and 
is esteemed as an article of food in those districts in which 


it occurs. It is a handsome creature, of reddish brown 
colour mottled with white, with a strong superficial resem- 
blance to the true lobster, from which it differs in certain 
very marked respects. As indicated by its common name, it 
frequents rocky coasts, the neighbourhood of Lundy being 
an especially favoured spot. It does not occur on the East 

The point which will first strike the observer in Palinurus 
is the total absence of the great forceps so characteristic of 
lobster and crayfish. All the legs tire similar, and terminate 
in simply pointed claws, though the first pair show in rudi- 
ment the condition described as sub-chelate for the shrimp 
(p. 169). Again, the antennules are half as long as the 
body, but the length is given by the great elongation of 
the peduncles, the flagella being exceedingly short. The 
antennae are very long, longer than the body, and are borne 
on very stout and spinose peduncles ; the scale is entirely 
absent. The carapace is very densely coated with spines, 
of which two are very large and project forward over the 
eyes, but the rostrum is very small. In both sexes the first 
pair of abdominal appendages is absent, the others are 
simple in the male and two-branched in the female. These 
are only a few of the peculiar characters of Palinurus, 
which separate it so markedly from the Astacidae; the 
absence of the great chelae is a point of special interest. 
It lives chiefly upon the little Molluscs which cluster about 
the rocks, and is one of the few Crustacea capable of 
making distinct sounds, produced by rubbing movements 
of a specially spiny part of the stalks of the antennae. 

The Reptant Crustacea with which we have been hitherto 
concerned have been large forms showing many points of 
interest, but which at most can only be hoped for very 
occasionally on the tidal rocks, and are therefore somewhat 
beyond our proper sphere. On the other hand, the forms 
to which we have now to turn are abundant everywhere on 
the rocks, can sometimes be kept for a considerable period 
in confinement, and are therefore objects of greater interest 
to us. These forms are the species of Galathea, and the 
porcelain crabs (Porcellana). We shall consider these two 
genera together as forming one family, for though sometimes 
widely separated, they show in many points great structural 


resemblance. They are often separated, because the por- 
celain crabs are in popular view crabs, while the Galathea 
would popularly be described as a kind of lobster. We 
shall see how nearly the two resemble one another, so that 
this family, like not a few others, may be described as 
linking crabs to lobsters. 

First as to Galathea when stooping over a rock pool 
paved with promising stones, you will not unlikely see 
darting through the water an animal whose movements are 
so swift that it seems to be gone before you are well aware 
of its presence. Momentary as the impression is, however, 
it will probably have convinced you that the motion is 
unlike that of a fish. If you employ all the artifices at 
your disposal, and by draining the pool, removing its stones, 
and searching its furthest recesses, compel the object of 
your search to reveal himself, you will probably find a 
Galathea. Even so, however, seeing is not catching, and 
there is many a slip between the Galathea and the collecting 
bottle. I well remember the first specimen I had the 
fortune to catch. The chase had been long, and the pool 
was deep, but at last the wary Crustacean had been got 
into a corner, and heedless of her footing the would-be 
captor made a sudden dart. It was successful, and for one 
joyful instant I held the prize in my grasp. But it was 
just an instant; there was a sudden jerk and a splash, and 
I was left in the pool with one great claw in my hand, 
while the Galathea twiddled his whiskers in insolent con- 
tempt from an inaccessible crevice. I then learnt that the 
"power of autotomy is possessed by the higher Crustacea 
to a very marked degree," but that information, though 
valuable, did not bring back the Galathea. Nor was I 
much consoled on learning further that "the autotomy is 
reflex and due to the stimulation of the sensory nerve," 
or in plain English that if I hadn't pinched the claw the 
Galathea wouldn't have thrown it off, for I defy anyone 
to catch a Galathea by one leg while floundering in the 
water, and not pinch that leg. It is therefore better, on 
the whole, not to catch your specimens by the legs, but 
to try and gently persuade them to enter a net or collecting 

When caught, you will find that Galathea at first sight 



somewhat resembles a very short and broad spiny lobster. 
The colour is variable, but in the commonest species, 
G. squamifera, which attains a length of about three inches, 
the prevailing tint is usually brownish blue. Very young 
specimens are, however, not infrequently brilliantly marked 
with bright blue and red. 
In marked contrast to 
Palinurus, we find that 
Galathea is furnished with 
a pair of long chelipeds, 
forming the first pair of 
legs. In so far it resembles 
the true lobster and cray- 
fish, but it will be noticed 
that only the first pair of 
legs bear forceps, not 
several pairs, as in cray- 
fish and lobster. With 
the gradual increase in 
the creeping habit, and 
the diminution of the 
power of swimming, the 
next two pairs of legs 
take on as their primary 
function that of support- 

ino- thp hnrlv inrl ln?p FlG - 51 Scaly squat-lobster (GaZaMea squami- 

oay, ana lose /gra) The ^^ is figure v d in a som ^ ew hat 

their power 01 prehension, unnatural position, in order to show the 
TVin ehirlpnf VrmlH nlr> structure of the tail, and afford a basis of 
me Student snouia alSO comparison with the lobster, Fig. 48. 

not fail to notice that 

with the broadening of the body, first obvious in Galathea, 
the insertion of legs also moves outwards, so that the body 
becomes more definitely adapted to the creeping habit. It 
may, however, be objected that it is not obvious in what 
respects Galathea shows a diminished power of swimming, 
in view of the frequent difficulty in effecting its capture. 
That it is not so good a swimmer as the true lobster can yet 
be proved both from structure and habit. As to habit, 
Galathea habitually creeps on its walking legs, and only 
darts backwards on the sudden advent of danger. In 
repose it keeps the tail bent a trifling point, but one 
fruitful in consequences. Then as to structure, compared 



with the lobster the tail is much shortened, relatively to 
the cephalothorax, its muscles are greatly reduced, and in 
short it is mechanically unfitted to function as an organ of 
locomotion for more than a limited period. 

Among the other interesting points of structure shown 
by Galathea are the following. The antenna are not 
beneath the antennules, but at the outer side of them. 
The peduncle of the antennules is long, and the flagella 
extremely short. This it will be remembered occurs also in 
Palinurus, and it is also found in all the forms above 
Galathea. The antennal scale is absent, as in Palinurus. 
As in Palinurus, further, the first abdominal segment bears 
no appendages in the female, and very rudimentary ones in 
the male, in Galathea this segment is indeed considerably 
reduced, owing to the sharp flexion of the body at the 
junction of thorax and abdomen. This flexion and 
reduction is, of course, universal among the crabs, and is 
of some interest because some naturalists would regard the 
reduction as directly the result of the pressure exerted 
during the bending process. But it is important to notice 
that the first abdominal appendages have disappeared in 
Palinurus before the bending of the abdomen has begun. 

Most of the above are characters indicating the approach 
of Galathea to the crabs, in which these structural peculiar- 
ities are further emphasised; but in addition Galathea shows 
certain special peculiarities. Note especially the condition 
of the last pair of legs. These are reduced to mere rods 
with a terminal brush of hairs and rudimentary chelae, and 
are habitually carried tucked underneath the gill-cover. 
In the figure they are shown spread out. The gill-cover, it 
will be noted, is no longer vertical, as in the crayfish, but is 
now oblique in position, and separated from the shield by a 
suture. The well-developed rostrum with spines character- 
istic of the species should also be noticed, and the reduction 
of the abdominal appendages, whose only function seems 
now to be to carry the eggs in the female. 

Two species of Galathea are common on our shores. The 
commoner is G. squamifera, while the larger, G. strigosa, is 
more usually found in deeper water. 

The first-named species has a short rostrum ending in a 
spine, and bearing four spines on each side, the last being 


the smallest. The chelae bear spines, but only on the inner 
margin of the meropodite and carpopodite (arm and wrist), 
and the outer margin of the propodite (hand). 

In the spinous Gdlathea (G-. strigosa) the rostrum has 
only three teeth on each side, and the great claws bear 
numerous spines on both margins. The two species are 
very neatly distinguished by the structure of the maxilli- 
pedes, as will be seen on reference to the table at the end of 
the chapter. 

The next forms to be considered after Galathea are the 
little porcelain -crabs, very different in appearance from 
G-alathea, less active and less beautiful, but no less interest- 
ing. As already indicated, the porcelain-crabs are sometimes 
widely separated from Galathea, 
but we shall consider both here as 
belonging to the same family 
(Porcellanidse), for they seem to 
be closely related. 

We have two British species of 
Porcellana, both very abundant, 
and occurring on the shore rocks. 
The larger, P. platycheles, is to be 

SOUght under Stones in muddy FIG 52. Hairy porcelain-crab 
nnnlcj TliP rra'h r!r,P nnf UVP in (Porcellana platycheles). The tail 

pools. me crab does not live in isinthe na turai position, that 

mud, SO that the Stones must be is< completely bent beneath 

those which from their position 

have a cavity beneath them, and the likeliest pools are 
those traversed by a little stream of water. Turn over 
such stones, and you will see on the upturned surface small 
muddy crabs with large flattened chelipeds, whose one 
method of defence seems to be the passive one of crouching 
down, with the curious great claws, which are densely 
fringed with hair, arranged at such an angle that they re- 
semble nothing so much as a flattened pebble adhering to 
the stone by means of a layer of mud. It is curious that 
although very common, and found considerably above low- 
tide mark, these crabs are familiar to very few people. 
This is partly because the localities which they haunt are 
not those in which the collector usually lingers, partly no 
doubt because the habit of crouching down and the coating 
of inud make them very inconspicuous. 


The other species, P. longicornis, though smaller, is much 
more conspicuous and brighter in tint. It is found under 
stones also, but not where there is mud, and usually in- 
habits deeper water than its hairy congener. My best 
specimens have been obtained from the roots of Laminaria, 
either pulled out of the deeper pools, or cast on shore after 
storms. The last constitutes a very important source of 
supply for the smaller and rarer Crustacea. After many 
an easterly gale the shore is strewn with giants from the 
marine forests, and every plant has brought away with it 
countless forms of animal life which once lodged in its 
roots, stems, and fronds. 

Presuming, then, that you have obtained specimens of 
both crabs, and that by a dexterous use of a camel's-hair 
pencil you have removed a portion of the mud from the 
hairs of P. platycheles, and so succeeded in revealing its 
shape to some extent, we will consider the characters of 
the genus. 

Both differ very markedly from Galathea in the shape 
of the carapace, for it is almost circular and much depressed 
in other words, truly crab-like. The abdomen is com- 
pletely flexed, as in crabs in general, but it is large, retains 
its seven distinct parts, and ends in a distinct, though 
small and delicate, tail fin. You should not fail to notice 
that, as in Galathea, the telson, or tail-piece, is curiously 
marked, being composed of several pieces. As to the 
appendages, the small antennules and the very long antennae 
in essentials resemble those of Galathea. The third maxilli- 
pedes are very interesting, because they present some general 
resemblance to those of Galathea and the lobster; but yet 
in the expansion of their basal joints they show an approach 
to the shutter-like structure seen in the true crabs. As a 
special peculiarity they exhibit a dense fringe of long hair 
on the inner margin of their terminal joints. The structure 
of the great claws differs in the two species, but in both 
cases they are so modified by the hollowing out of the wrist 
(carpopodite), that they can be held in a retracted position 
(see Fig. 52). This is characteristic of the crabs as com- 
pared with the long-tailed forms, which carry their chelipeds 
outstretched. The next three pairs of appendages are walk- 
ing legs, used for the support of the body. As in Galathea, 


the last pair of legs is modified to form two slender rod-like 
structures, habitually kept folded beneath the lateral margin 
of the carapace, and terminating in minute chelae with a 
brush of hairs. In the figure they are represented in the 
unfolded condition. Besides the terminal swimmerets, the 
abdomen in the female bears four pairs of slender hairy 
appendages used for carrying the eggs, -while in the male 
there is only a single pair of slender rods. The reduction 
of the abdominal appendages in the male should be noticed, 
as it is very characteristic of crabs compared with long- 
tailed forms. The appendages of the male belong to the 
second abdominal segment, and the appendages of the first 
segment are also absent in the female, as in crabs. The 
porcelain-crabs are passive little creatures as a general rule, 
showing marked preference for secluded situations, and 
clinging tightly- to stones or weed when disturbed. In 
spite, however, of the crab-like appearance, they still retain 
the power of swimming, as may be often seen in captivity 
in the minute porcelain-crab. Occasionally this species 
gives up its sedentary habits and takes to active swimming 
through the water. The motion is, of course, backwards, 
and it is very curious to notice that although it begins its 
journey in the normal position, the weight of the heavy 
claws seems to invert the body, and it very speedily falls 
over on its back. It is a very interesting sight to see the 
little creatures lying on their backs in the water and 
propelling themselves backwards by vigorous jerks. It is 
obvious that under such circumstances the long antennae 
are of much use in helping to direct the movements and 
avoid collisions. I have never seen the hairy porcelair- 
crab swim, and if it does so the heavier claws must hand'- 
cap it considerably, and make tbe movement exceedingly 
fatiguing. The whole shape of the claws is considerably 
more crab-like than in the other species, and from the 
nature of its habitat one would not expect that swimming 
would be frequently indulged in. Both it and the smaller 
species, when turned on their backs, flap their tails to assist 
their efforts to regain the natural position. In specimens 
kept in confinement the dense fringe of hairs on the third 
maxillipedes should also be noticed. In the hairy porcelain- 
crab the hairs are used as a comb to clean the antennae and 


antennules from any adhering particles of mud a very 
necessary matter in animals living ' in muddy situations. 
Both species have also a habit of holding the fringes out 
at arm's length, and then sweeping them inwards ; it is 
probable that in doing this food -particles are entangled 
among the hairs, which thus serve as fishing-nets. 

There is no difficulty in distinguishing between the two 
species of porcelain - crabs, for they are very unlike one 
another in appearance. 

In P. platycheles the carapace is usually about half an 
inch broad, and the length of the great claws is somewhat 
over an inch. The upper surface in life is so densely 
covered with fine mud that no colour is visible ; but the 
under surface is whitish, and when carefully cleaned the 
upper has a reddish tint. The hairy porcelain-crab, as it is 
called, is a very interesting species on account of its adapta- 
tions to a life in turbid water. It has been proved by 
experiment that, hardy as the common shore crab is, water 
containing mud is extraordinarily fatal to it. This is due to 
the fact that the gills, as in all Crustacea, are external 
structures, though they lie within a protecting gill-chamber. 
In consequence they are exposed to the action of the mud 
in the water of respiration. The particles settle on their 
surface, and produce an effect which is, in a rough way, 
analogous to the effect produced by deposits of dust in our 
lungs, and this speedily asphyxiates the crab. If, therefore, 
a crab is to live in sand or mud, it must have a special 
mechanism to prevent the particles gaining access to the 
gills. This is generally effected by the development of 
hairs, placed on the general surface of the body, but 
especially on the path of the respiratory current. The chief 
point of entrance of the water to the gill-chamber is in most 
crabs at the base of the great claws. If' you examine For- 
cellana platycheles when at rest on a stone, you will see that 
the legs in general, but the great claws in particular, are 
densely fringed with hairs. These hairs, as is easily seen, 
act as sieves, entangling the fine particles, and allowing pure 
water only to pass through them. The sifting action of the 
hairs is greatly increased by the fact that they are branched 
and serrated, a point easily demonstrated by microscopic 
examination. The third segment of the rudimentary legs is 


also hairy, and in life lies at the sides of the carapace, pre- 
venting the access of mud to the posterior part of the gill- 
chamber. These legs are also periodically unfolded, and 
their terminal brush of hairs used to clean out the groove 
and remove any adhering particles. This curious manoeuvre 
may often be seen in forms kept in confinement. We have 
already noticed the similar cleansing process practised on the 
sensitive feelers. 

The special characteristics of P. platycheles are its general 
hairiness, and the large size and flattened shape of the cheli- 
peds. The front of the carapace is furnished with three 
triangular teeth, the middle one being the largest. 

The minute porcelain - crab (P. longicornis) usually 
measures in large specimens under a quarter of an inch 
across the carapace. In the males the colour is bright red, 
but is somewhat less brilliant in the females. The great 
claws are of unequal size, and are more or less prismatic in 
shape. Like the rest of the body, they are quite smooth 
and devoid of hairs a marked contrast to the preceding 
species. In the male, however, the " fingers " (chelae) of the 
left great claw r are curiously twisted, and covered internally 
with a dense pubescence of brown colour. The "fingers" of 
the female are less markedly twisted, and the pubescence is 
absent. In both sexes the antennae are about twice as long 
as the carapace, and the front of the carapace is furnished 
with three teeth, of which the middle one is deeply 

Both the porcelain-crabs are abundant at most parts of the 
shore, and live well in confinement. 

The next family is the PaguridaB, including our own very 
curious hermit-crabs and the cocoanut-crabs of the tropics. 
All these have long abdomens, like true Macrura, but the 
abdomen is more or less soft, unsegmented, and usually un- 
symmetrical. Most of the forms have in consequence 
acquired the curious habit of availing themselves of the 
shells of other animals, usually Gasteropods, and carrying 
these about with them as a house. The appendages of the 
abdomen are correspondingly reduced, the chelipeds are very 
large and usually of unequal size, and the two last pairs of 
walking legs are reduced. 

The true hermit- or soldier-crabs belong to the very large 


genus Pagurus, often divided into a number of sub-genera ; 
it will be sufficient for us to consider the British species as 
belonging to Pagurus itself, although they strictly fall into 
the sub-genus Eupagurus. 

On the East Coast there is only one common species near 
the shore, and that is P. bernhardus, or Bernard the Hermit, 
as it is commonly called abroad. Of this form small 
specimens are abundant, often extraordinarily abundant, in 
all shore pools. In the Firth of Forth after storms the 
beach is sometimes literally paved with hermits, and every 

FIG. 53. Common hermit-crab (Pagurus bernhardus) in the shell of the whelk, 

rock pool has its representatives. These inshore forms 
inhabit the shells of the different species of periwinkle, 
Trochm, Purpura, and of the smaller whelks, often much 
damaged specimens the broken top of a very large 
"buckie" seems indeed to arouse specially keen competi- 
tion. The size of the hermits depends upon that of their 
habitation, for the hermit changes its shell as it grows, so 
that all these specimens are necessarily small ; the fact that 
many of them will be found to be carrying eggs shows, 
however, that maturity does not depend on size alone. 
When removed from their shells it will be seen that all 
these forms have an abdomen of blue colour. With these 


the hermit-crabs dredged from deep water, or cast ashore 
after storms, seem at first sight to be markedly contrasted. 
They inhabit the large shells of full-grown specimens of 
Fusus or Bticcinum, shells often nearly six inches in length 
and heavy in proportion, and the hermits reach a size 
commensurate with that of their dwellings. The abdomen 
is a deep brick-red, and the rest of the body deeper in 
tint than in the shallow-water forms. It requires some 
study to convince one's self that such hermits are not specifi- 
cally distinct from the more familiar forms found on the 
tidal rocks, and the fact that the latter become mature in 
shallow water, almost justifies one in speaking of them 
as a variety. 

One other point of interest about the hermits is their 
habit of living in symbiosis or partnership with other 
animals. In certain localities the hermits very commonly 
inhabit shells covered externally by the beautiful zoophyte 
Hydractinia. This seems, however, to depend very largely 
upon the locality. Most hermits from deep water have, as 
companions within their shells, one or more specimens of a 
very beautiful worm, Nereis fucata (see p. 106). So common 
is this association, that in some places fishermen catch the 
hermits, and turn them out of their shells for the sake of 
the partner worms, which are used as bait. It is not easy 
to see what the hermit gains by the presence of the worm, 
but at least it is not injured by it, as it is by another 
common associate, the parasitic Peltogaster, which hangs 
like a sac from the under surface of the abdomen in very 
many hermit-crabs. 

As everyone who has tried to keep hermits in confinement 
knows, they are exceedingly sensitive to unfavourable con- 
ditions, especially to a diminished oxidation of the water. 
The first sign of discomfort displayed is the tendency to 
quit the shell, or to change rapidly from one shell to another, 
and this restlessness is usually quickly followed by death. 
It is difficult to say whether this delicacy of constitution 
is due to a difficulty in respiration produced by the shell, 
or to that racial decadence which has made the appropriation 
of the shell necessary. If, however, you wish to keep the 
hermits alive, they must be allowed a large bulk of water, 
as frequently renewed as possible. Under such conditions 


they form very interesting pets; the explorations in all 
directions carried on by the long antennas, the flickering 
movements of the antennules, the sudden recoil within the 
shell at the approach of danger, and the peculiar gait, should 
all be noticed. Also the fact that just as the original owner 
of the shell was an unsymmetrical, twisted animal, so also 
the body of its present possessor is distinctly lopsided and 
coiled. The want of symmetry is indicated externally in 
the inequality of the great claws, but is more obvious when 
the dying hermit drags its soft body out of the stolen shell, 
and shows all its twisted length. 

In the dead specimens the following points can be made 
out. Though the great claws and walking legs are strongly 
calcified, the rest of the body is soft and thin-skinned. The 
carapace is delicate, and does not cover the last thoracic ring, 
which is free, as it is in the last family. The abdomen is 
much longer than the cephalothorax, and is twisted to the 
right side. The antennae are very long, are placed beneath 
the antennules, and have a rudimentary scale. In their 
general structure the antennules resemble those of the last 
family, that is to say, their filaments are short as contrasted 
with the long ones of lobster and crayfish, and the upper 
is thickened and fringed with hair. The eyes have very 
long stalks and are very mobile. We have already spoken 
of the inequality of the great claws ; the next two pairs of 
legs are simple, very long, and strongly calcified ; they are 
used for locomotion. The last two pairs, on the other hand, 
are shortened and greatly reduced. They do not project 
from the shell, and as in the case of the last pair of legs 
in the preceding family, terminate in very rudimentary 
chelaa. The abdomen has mere traces of calcification on its 
upper surface, but terminates in a distinctly calcified telson, 
which shows some signs of being, as in the preceding family, 
calcified in several pieces. In both sexes the last pair of 
abdominal appendages is present; the left is much better 
developed than the right, and forms a sickle-shaped structure 
which attaches the hermit to its stolen shell. The right 
appendage is smaller, but is also hard and of somewhat 
similar shape. Besides these paired appendages the left 
side of the abdomen in the female bears four unpaired 
appendages, of which three are anterior, very hairy, and 


used for carrying the eggs. The fourth, separated by a long 
interval, is very much smaller. In the male there are three 
unpaired appendages of small size. The unsymmetrical 
condition of the abdominal appendages in Pagurus is a 
point of much importance. 

We shall only mention here two species of Pagurus, the 
common hermit, P. bernhardus, and the closely related P. 
prideauxii of the West. "Bernard the Hermit" is recog- 
nised by the fact that the great claws have their surface 
covered with spinous tubercles and granules, and that the 
terminal segment of the walking legs is twisted and 
expanded. It is abundant everywhere. 

The P. prideauxii of the West Coast is very similar to 
the common hermit, but the chelae are less tuberculated, 
and the last joint of the walking legs is scarcely twisted, 
not flattened, and grooved at each side. This form does not 
occur on the East Coast, but is included here on account of 
the interesting fact that it almost always bears the sea- 
anemone Adamsia palliata on the back of its shell another 
interesting case of commensalism in these hermits. In the 
Clyde, and on other parts of the West and South, P. 
prideauxii and its messmate are abundant. 

The other numerous British species of Pagurus mostly 
live in deep water, or are confined to the South and West. 

The hermit-crabs possess so many obvious peculiarities 
that they are quite unmistakable, but the next crab we shall 
consider, though probably nearly related to the hermits, is 
not infrequently erroneously described as a spider-crab. 
This is Lithodes mala, the northern stone-crab, an animal 
interesting alike in its distribution, its structure, and its 
superficial resemblance to the true spider-crab Mala. As 
the common name indicates, it is a northern species, one of 
the few forms whose presence on the East Coast compensates 
for the absence of the rich Mediterranean fauna of the 
West and South. It attains a large size a span of twenty 
inches, with a breadth of carapace of four inches, and 
inhabits deep water. Though not a littoral form, it is, 
however, included here because of its interest, and because 
it may be not infrequently obtained from friendly fishermen, 
and occasionally finds its way as a curiosity into fishmongers' 
shops. Anyone accustomed to the Crustacea of the West 


seeing a specimen for the first time, and noting the length 
of leg, the triangular carapace, and the dense coating of 
spines, is likely at once to pronounce it to be a spiny spider- 
crab. Not infrequently he writes to the newspapers to 
proclaim the fact; the spiny spider-crab as an inhabitant 
of the North-east may indeed be relied upon to appear as 
regularly as the nightingale, the humming-bird, the sea- 
serpent, and the other phenomena of the dead season. 

If you are fortunate enough to obtain a specimen, you 
may easily enough demonstrate to yourself the reasons why 
Lithodes is not a spider-crab, but is relegated to a family of 
its own, the Lithodidae, which is placed at a considerable 
distance from the true crabs. 

The stone-crab has a triangular spiny carapace prolonged 
into a long rostrum, which bears eight spines. There are 
no orbits, or eye-sockets, and the eyes are placed at the 
inner side of the antennae (contrast crabs). The antennules 
lie beneath the eyes, and have a very long stalk, and very 
short flagella (cf. hermit-crabs). The antenna? are long, and 
placed not in a complete socket, but in a gap between a 
spine on the carapace and one on the anterior end of the 
gill-cover (cf. Porcellana, and contrast crabs). The gill- 
cover itself is nearly vertical (cf. Pagurus and Galathea), 
and divided into several pieces. As in Pagurus, the last 
ring of the thorax is movable, and is not covered by the 
carapace, and its appendages are greatly reduced, and 
concealed in life beneath the carapace. As in Pagurus and 
Galathea, the third maxillipede is completely leg-like, and 
does not form an operculum, as in the true crabs. The first 
pair of legs only are truly chelate, the others are very long. 
Both carapace and legs are spiny, and are of the same dull 
red colour. 

So far Lithodes has only been seen to resemble Pagurus 
in those points in which Pagurus itself resembles Galathea, 
or even more distant forms, but in the structure of the 
abdomen, Lithodes, on the other hand, shows a striking 
affinity to Pagurus, and to Pagurus alone. In Lithodes, as 
in Pagurus, the abdomen is incompletely calcified, the first 
two segments are large and visible on the dorsal surface, the 
remaining segments are permanently flexed beneath the 
thorax. In the female these segments are markedly un- 



symmetrical, the left side being better developed than the 
right, and bearing four unpaired appendages used for 
carrying the eggs (cf. Pagurus). In the male the abdomen 
is symmetrical, but uncalcified, except for small lateral plates. 

The student should not fail to notice that the four genera 
just discussed Galathea, Porcellana, Pagurus, Lithodes 
show in several respects close interrelationship. The point 
of special interest, however, is that they fall into two sets 
Galathea and Porcellana on the one side, and Pagurus 
and Lithodes on the other and that in each set we have 
a long-tailed (macrurous) form (Galathea in the one and 
Pagurus in the other) and a short-tailed form (Porcellana 
arid Lithodes), the brachyurous characters having been 
acquired independently 
in the two cases. The 
fact will serve to illus- 
trate what is meant by 
saying that the Deca- 
pods cannot be logically 
classified into Brachyura 
and Macrura, for not 
only are forms like 
Galathea and Porcellana 
transitional between the 
two, but the brachyurous 
habit seems to have been 
acquired independently 
in several groups, and 
the rigorous application 
of the classification must 
result in the separation 
of closely allied forms. 
Thus if we put porce- 
lain-crabs and the stone- 
crab together among 
other crabs, as is often done, we necessarily ignore the fact 
that they are more closely allied to Galathea and the 
hermit-crab respectively than to one another. 

The next form to be considered is the pretty little 
masked crab (see Fig. 54), Corystes cassivelaunus, be- 
longing to the family Corystidse, which includes only one 

FIG. 54. Masked crab (Corystes cassivelaunus). 
In part after Herbst. 


other British genus. The masked crab is not very often 
found between tide-marks, as it usually lives in sand in 
fairly deep water, but it is a species very commonly cast 
upon the shore after storms, and may often be found even 
in summer among the dried masses of wreckage at high- 
tide mark. The not very appropriate English name was 
given to it by Bell because of the fact that the regions of 
the carapace are very distinctly marked, and their grooves 
are so arranged as to form a somewhat indistinct outline 
of a man's face. This is only apparent in fresh specimens, 
and at times is considerably more like a lion than a man. 
Fresh specimens are pale red in colour, but the colour soon 
fades to bluish white. In length the carapace usually 
measures rather over an inch, and it is one-third longer than 
broad. The sexes are easily distinguished, for while in the 
male the chelipeds are twice as long as the body, in the 
female they are of the same length. Further, as in the true 
crabs, there is a fusion of abdominal segments in the male, 
so that while the abdomen of the female has several pieces, 
that of the male only appears to have five. As in all the 
remaining Decapods, the abdomen is kept permanently 
flexed beneath the carapace, is very small, and without 
trace of tail fin; it is broader in the female than in the 
male, and it bears four pairs of egg-carrying appendages, 
as compared with the two pairs of small rods in the male. 
The eyes are placed in orbits into which they can be 
retracted. In all these respects Conjstes resembles the true 
crabs; in the following it resembles the long-tailed or 
anomalous forms which we have just been considering, or 
is peculiar. 

The antennae are long, and are supported on long, flexible 
stalks, whose three joints are all freely movable and inserted 
at such angles as to bring the two antennae very close to 
one another. They are placed beneath the eyes, the orbits 
of which would be widely open below were it not for the 
basal joint of the antennal peduncle. The third maxilli- 
pedes are long and narrow, but in the reduced size and 
method of insertion of the three terminal joints they recall 
those of true crabs. The first two segments of the abdomen 
are visible on the dorsal surface, and the first is much better 
developed than in crabs, in which it is more or less reduced. 


The masked crab is very easily recognised owing to the 
peculiarly elongated shape of the carapace, which terminates 
anteriorly in a deeply notched rostrum, and is furnished 
with three distinct spines. These points are readily made 
out in the figure. The elongated antenme are also peculiar 
and characteristic. As already indicated, the nature of 
their insertion is such that the inner surfaces of their flagella 
are, or can be, closely apposed. These apposed surfaces are 
densely fringed with hair, and, according to Mr. Garstang, 
the respiratory current is at least at times downward through 
the tube formed by the antennae. It will be recollected 
that in Crustacea in general the gills are washed by a 
constant stream of water which enters the gill-chamber at or 
near its posterior end, and leaves it anteriorly near the 
mouth. We have already noticed in the mud-loving Por- 
cellana platycheles that the numerous hairs covering the 
body sift the mud from the incoming water, and so protect 
the delicate gills from injury. The masked crab usually 
lives buried in sand, with only its long feelers protruding. 
It is obvious that in this position it is almost impossible 
that the respiratory current should be of the usual postero- 
anterior type, and we therefore find that it is at least at 
times reversed, entering at the anterior end of the gill- 
chamber after passing down the antennal tube, and leaving 
at its posterior end. The dense hairy fringe of the antenna 
sifts out the particles of sand just as the mud is sifted out 
in Porcellana. The great flexibility of the antennal stalks 
also permits of the periodic cleaning of the antennas by the 
drawing of one over the hairy surface of the other. 

It is interesting to note that another member of the 
family Corystidee, Atelecyclus heterodon, also occurring on 
British coasts, approaches both in appearance and in struc- 
ture the crabs much more nearly than does Corystes itself 
It is exclusively an inhabitant of deep water. 




II. REPTANTIA, creeping forms including lobsters, hermit-crabs and 
their allies, and true crabs (see next chapter). For full definition of 
Reptantia, see p. 163. 

Of the five pairs ^ 

1. Fa,, AstacM,. 

2. Fara. 

Pal inn - 

3. Fam. Porcel- 


None of the legs \ 
bear forceps . J 

One pair of legs , Tail fan present, -\ 
only with for- abdomen sym- V 
ceps. Last pair I metrical .J 
of legs or 1 No tail fan, ab- /-Tail long and . v -n i 
last two pairs domenunsym-{ soft . . 4. Fam. Paguridae. 
aborted . * metrical . ^Tail intumed 5. Fam. Lithodidre. 

, Fam. Corystidae 
from true crabs by 
long antennae and 
leg-like maxilli- 

Common lobster, Homarus 
vulgaris. For specific char- 
acters see text. 

Norway lobster, Nephrops nor- 
kidney-shaped . / vegicus. See text. 

One pair of legs^ 
only with for- I 
ceps. All legs | 
normal . J 

1. Fam. Astacidae. T Rostrum short, 
Long - tailed J eyes rounded . 
forms with largel R ^ , 

antennal scale . I 

2. Fam. 


Spiny forms witrn 
Palinu- long antennules ! 
.j and no antennal | 
I scale . .J 

3. Fam. Porcel- 
lanidae. Last 
pair of legs re- 
duced to rods . 

^Carapace ovate, 
with distinct, 
rostrum Gala- 

Carapace nearly 
circular, with- 
out distinct ros- 
trum Porcel- 
lana . 

Rock lobster, Palinurus vul- 
garis, the only British 

In G. squamifera the meropo- 
dite (p. 174) is longer than 
the ischiopodite, and bears 
one large terminal spine and 
five little ones. 

In G. strigosa the ischiopodite 
is longer than the meropo- 
dite, which bears two 

'In P. platycheles the body, and 
especially the chelipeds, are 
covered with hair. 

In P. longicornis the body and 
chelipeds are smooth. 



4. Fam. Paguridne.^ n , ,. -, - fin Eupagurus bernhardus the 
Abdomer! long Chelipeds of un- ohelipeda bear S p inou s tu- 
,,] __r>i. _I-~T ii equal size, tne i i *_ 

and soft, shel- 
tered within 
Mollusc shell . 


i E. prideauxii they are less 

^ m ;^ odi t ; | Rostrum long, last^ 

turned but in- 1 pair of le s ^~ l nly British species, LithocUs 
completely cal- 

mentary Li- j 
thodes , . J 

Fam.Corystid*. fCarapace ovate- C 
Antenna/ longJ Cor y stcs ' *\ 


' Cor y. stss _ 

and hairy 

. I Carapace circular /Only British species, A. 
v Atelecydus .\ heterodon. 


There is much that is interesting in regard to the distribution of 
the Crustacea mentioned in this chapter. While the common lobster 
occurs everywhere in suitable localities, the rock lobster (Palinurus) 
only occurs on the South and West, and is most abundant in the 
South. On the other hand, the Norway lobster, so abundant off the 
East Coast of Scotland, is rare in the South and South-west of England. 
On the East Coast, e.g. at St. Andrews, the scaly Galathea (#. 
squamifera) is the only species of Galathea found between tide-marks ; 
at places like Ilfracombe and Torquay G. strigosa and other species are 
to be found there. The porcelain-crabs seem to occur wherever the 
conditions are favourable. Of the hermit-crabs the common one 
occurs everywhere, while E. prideauxii is confined to the South and 
West, where, however, it does not occur between tide-marks. The 
northern stone-crab (Lithodes) is confined to the Northern parts of 
our area, and is especially abundant off Aberdeen, where it reaches a 
great size. The masked crab and its ally Atelecydus occur at most 
parts of the coast where the conditions are favourable. 


Common spider-crabs Their coating of weed The general characters 
The edible crab Its distribution and habits The shore crab 
Different kinds of swimming crabs The pea-crab Movements of 
the Decapod Crustacea Process of moulting Development of 

IN this chapter we have to consider the true crabs, one of 
the most interesting groups of the Crustacea, including 
forms which are essentially littoral in habit. We have 
already seen that the porcelain-crabs, the stone-crab, and 
the masked crab, show striking external resemblances to the 
true crabs, such as the spider-crabs, the shore crab, and the 
edible crab, so that a little care is necessary in defining the 
Brachyura, or short-tailed true crabs, in the narrow sense. 
That the carapace is usually broad in proportion to its 
length, and the tail small without tail fan, and reflexed 
beneath the body in all crabs, it is hardly necessary to 
repeat. More subtle points are the fact that eyes, an- 
tennules, and antennae, are placed in complete sockets, that 
the third pair of maxillipedes form flattened plates (opercula) 
instead of being leg-like, and that the whip (flagellum) of 
the antennae is always short. Lest it should seem, however, 
that this distinction has been made too sharp, it should be 
carefully noted that in the curious rounded crab Atelecydus, 
mentioned in the last chapter, the maxillipedes are com- 
pletely flattened, and meet in the middle as they do in the 
true crabs. Such facts make the classification of the 
crabs as difficult as it is interesting, but as we are con- 
cerned only with British forms, it is sufficient to regard 



as true crabs the forms showing the characters mentioned 
above, Atelecydus being excluded because of the long 

Of the true crabs we shall consider here only three 
families, into two of which most of our British forms 

The first family is that of the spider-crabs, or triangular 
crabs, as the Germans call them. There is generally no 
difficulty in recognising at once the British members of this 
family. Its scientific name (Oxyrhyncha) refers to the 
pointed rostrum which forms the anterior angle of the 
three-cornered carapace. The popular name of "spider" 
refers to the way in which the small body is suspended on 
the long spidery legs. Spider-crabs differ, however, very 
markedly from their terrestrial namesakes in regard to 
their movements; far from being agile, they rival the 
historic tortoise in the slowness and deliberation of their 
methods of progression. Whether the sea-grass grows 
beneath their feet or not, it is impossible to say; but it 
certainly does grow freely on their backs, most of them 
carrying about with them a perfect forest of weeds and 

Our largest spider-crab is Maia squinado, the great " sea- 
spider," spiny spider-crab, or devil's crab of the South and 
West. It is collected in large quantities as an article of 
food in the South-west, and is also abundant in the Medi- 
terranean, where it was well known to the ancients. The 
colour is reddish brown, but in life, as in other spider-crabs, 
the body is usually densely clothed with seaweed and zoo- 
phytes, attached by means of numerous bristles. The 
carapace is ovoid in shape, and prolonged anteriorly into a 
bifid rostrum with diverging horns. Besides the covering 
of bristles, its surface is furnished with numerous tubercles, 
and is strongly spinous at the margins. As in crabs in 
general, the lowest joint of the stalk of the antenna is 
firmly fused to the carapace. The abdomen is seven-jointed 
in both sexes. The carapace may attain a length of eight 
inches, and then would be about six inches broad, the legs 
having a span of fifteen inches. If specimens both of this 
crab and of the stone-crab (Lithodes maia, p. 187) can be 
obtained, it will be found a very useful exercise to contrast 


the two, noting the superficial points of resemblance, and 
the real points of contrast. Unfortunately the two are not 
likely to be both found in the same locality. 

The next form is one which is not edible and has therefore 
no common name. This is unfortunate, because it is in 
some places extraordinarily common, almost as common as 
that ubiquitous form which has appropriated the name of 
"shore crab" par excellence. This is Hyas araneus (see 
Fig. 55), the common spider-crab of the East Coast. 
Abundant as it is, it is not a form often seen except when 
searched for, and to very many people is known, if known 
at all, only by the dead specimens flung on the beach after 
storms. Nevertheless, in the right places one may find a 
dozen large living specimens in the course of half an hour. 
What are the right places ? is the question naturally asked. 
Two localities I have always found specially productive. 
First, deep rocky pools, preferably with overhanging edges 
densely overgrown with the finer kinds of weed and with 
zoophytes, whose waters never completely drain away, even 
at the lowest tide. Secondly, those beds of rounded boulders 
overgrown with Irish moss and red seaweeds, which are 
sometimes exposed for a short time at low spring tides. 
In such places the common spider-crab is generally abundant, 
but I have never found it so in places where there was not 
abundant moisture, and a dense growth of red seaweeds, 
zoophytes, and sponges. Similar growths also cover the 
back of the crab, and often conceal most of the peculiarities 
of structure. Your specimens are not likely to live very 
long in captivity, and while they live are often of more 
interest on account of the delicate zoophytes they bear on 
their backs, than because of their own habits, which are 
chiefly interesting because of their profound leisureliness. 
When they succumb to the injurious effects of their new 
surroundings, they may be carefully cleaned and the structure 
made out. 

The process of cleaning is best accomplished by picking 
off the encrusting weeds bit by bit with forceps. As you 
do so you will find that they are attached by hook :d hairs 
of remarkable appearance, which cover the surface of the 
body, and are often very conspicuous in the dried specimens 
found upon the beach. The hairs are of very considerable 



interest to those who care about the problems of evolution. 
Not only are they well adapted for their function of bearing 
the spider-crab's "forest of Dunsinane," but the crab itself 
actually attaches weeds and zoophytes to them. When the 
hairs are removed the carapace will be seen to be covered 
with the numerous tubercles so characteristic of the spider- 
crabs in general. It is dull in tint, inclining towards red 
on the upper surface, young and small specimens being 
often very distinctly red in colour. 

The general points named above having been made out, 
we may proceed to consider the special characteristics of 

Fio. 55.Hyas araneus, the common spider-crab. The coating of 
hairs is only indicated. 

The carapace is broad, elongated, and triangular, only 
slightly arched, and prolonged anteriorly into a bifid 
rostrum, whose converging halves are flattened above and 
deeply hollowed beneath. Immediately behind the orbit 
there is a very characteristic spear-shaped process. The 
abdomen is seven-jointed in both sexes. In large speci- 
mens the carapace may have a length of over three inches, 
and a breadth of over two. In such a specimen the legs 
would be over five inches long. The specimens ordinarily 
found on the rocks are, however, likely to be smaller than 


Besides Hyas araneus we have another British species 
H. coardatus which is also very abundant, but occurs in 
deeper water. It is very much smaller, and is easily 
recognised by the shape of the carapace. This is suddenly 
contracted behind the post-orbital processes, so that the 
regularly triangular shape of H. araneus is lost. Young 
specimens of this species are sometimes to be found far out 
on the rocks, or among the weed flung ashore after gales, 
but are difficult to distinguish from the young of H. araneus. 
Indeed, some authorities deny that the two species are 

Belated to Hyas is the genus Pisa, including small, hairy 

FIG. 56. Stenorhynchus phalangium, the long-legged spider-crab. 

crabs, not very dissimilar to Hyas in appearance. The two 
species are too rare in Britain to merit description. 

The last two genera of spider-crabs are even more spidery 
than the preceding, and differ from them in the great length 
of the walking legs, as contrasted with the short and thick 
great claws. The great claws are especially thickened in the 

Under stones at low water there may be occasionally 
found Stenorhynchus phalangium (see Fig 56), a representa- 
tive of the first genus. The carapace forms an elongated 
triangle, and is prolonged into a long tapering bifid rostrum. 
The protruding eyes cannot be retracted into the circular 
orbits, and are peculiar in bearing on their surface a tuft of 


bristles. The rostrum is shorter than the stalk of the outer 
antennae. The abdomen has six joints in both sexes, the 
legs are about four times the length of the carapace, are 
very slender, hairy, and usually covered with weed. 
Another species occurs in deeper water. 

The other genus Inaclms is represented in shallow 
water by /. dorhynchus, found occasionally beneath stones. 
The carapace differs from that of StenorhyncJius in being 
sub-triangular, nearly as broad as it is long, with short, bifid 
rostrum. The eyes are retractile, and the orbits elongated, 
instead of circular. The species is characterised by three 
spines on the gastric region of the carapace ; of these two 
are anterior and one posterior, the three forming a triangle. 
There is another species of larger size, but it occurs in 
deeper water. 

The next family of crabs is that of the Cyclometopa, or 
crabs with rounded forehead. In them the carapace is 
broad and arched in front and narrows posteriorly; in its 
whole shape it contrasts markedly with that of the spider- 
crabs. The common shore crab is an admirable and easily 
obtainable example of this family, and in it the general 
characters may be readily observed. Notice how very 
different is the shape of the carapace from that of the 
spider-crabs. The rostrum has disappeared, and in its place 
we have a rounded region between the eyes known as the 
forehead. From the eyes the margin of the carapace slopes 
outwards and backwards, and is strongly toothed; this is 
the antero-lateral margin. Next, the margin slopes inwards 
and backwards, this region being known as postero-lateral ; 
it is untoothed. Finally, the two postero-lateral borders are 
united by a line, the posterior margin. It will be noticed 
that the carapace is here broad in front, where in the 
spider-crabs it is narrowest, and narrows behind where that 
of the spider-crab broadens out. Most of our commonest 
crabs belong to this family, and as these are largely dis- 
tinguished by the shape and teeth of the carapace, it is 
worth while being clear as to terminology before beginning 
the study of the individual crabs. 

The Cyclometopa are distinguished from spider-crabs not 
only in general shape, but by the swiftness of their move- 
ment s and their high intelligence. Quick at offence and 


defence, bold in attack, swift in flight, and ingenious in 
artifice, not many of the arts of war remain unknown to 
them. Together with the next family, which has but few 
representatives on our shores, they represent the highest 
point to which the Crustacea have attained. The high 
specialisation is seen in many of their structural peculiarities, 
some of which we have already discussed. 

The first member of the family to be considered is the 
edible crab, the crab of the fisher-folk, Cancer pagurus of 
science (see Fig. 8, p. 26). This familiar crab is abundant 
in all the European seas, inhabiting all depths of water up 
to about twenty-five fathoms. It is the object of an im- 
portant fishery, especially in England, where it is more 
relished than on the Continent. Though always caught on 
a large scale in crab-pots in the deep water off rocks, 
specimens of considerable size are nevertheless to be found 
on the rocks themselves, and are there caught by the fisher 
children. When exposed by the turning over of the 
stones under which they lurk, they have a peculiar 
habit of tucking in the legs under the broad and flattened 
carapace, so as to offer only its strong surface to the 

The special characters are as follows. The carapace is very 
broad and only slightly arched, the forehead narrow with 
three short similar teeth, the long antero-lateral margin is 
nine-lobed, while the shorter postero-lateral margin is entire 
and marked by a marginal line. In the great forceps the 
movable part is black, and furnished on its inner side with 
blunt rounded projections. The walking legs are all similar, 
the last ending like the others in a thin pointed claw. Eor 
these points see the figure. 

The next form is the shore crab (Carcinus mcenas), to 
which allusion has already frequently been made. It is 
abundant everywhere in shallow water, occurs in many 
colour varieties, and is extraordinarily hardy and successful. 
A charming pet, it will live long in captivity, even under 
unfavourable conditions, so long as it is allowed an oppor- 
tunity of occasionally quitting the water in which it is 
living, and is well fed. 

As to structure, the following points are worth notice. 
The carapace is broader than it is long, well arched, with 


three teeth in the projecting forehead, and five in the 
antero-lateral margin, which is much shorter than the 
postero-lateral margin. The great forceps are short, the 
hand has a double keel. The terminal joint of the last 
pair of walking legs is slightly expanded and flattened. 
As in the Cyclometopa in general, the abdomen is five- 
jointed in the male, and seven-jointed in the female. 
The females will be found not infrequently carrying the 
bright orange eggs attached to the hairy abdominal 

The next crab is one which is much more likely to be 
found on the shore after storms than living under natural 
conditions. This is Portumnus variegatus, a peculiar little 
swimming crab, common off sandy shores, and easily recog- 
nised at a glance by the shape of its carapace. This is 
peculiar in being as broad as it is long, the antero-lateral 
and postero-lateral margins being rounded instead of meet- 
ing at a sharp angle. The last walking leg is, as in the 
next genus, but to a less extent, converted into a swimming 
paddle, the terminal joint being broad and flattened, and 
the penultimate broad, rounded, and compressed. This 
crab, which has no English name, is a beautiful little 
creature, of mottled purplish white tint. 

Finally, we come to the large genus Portunus, including 
the true swimming crabs, popularly called "fiddlers" from 
the peculiar motion of the last pair of legs. These ap- 
pendages are completely converted into swimming paddles, 
and enable the crabs to dart rapidly through the water, 
thus taking on the function exercised in ancestral forms by 
the tail. In general shape the fiddlers resemble the shore 
crab, the carapace bearing similar teeth on its margin, but 
it is much flatter and slightly different in its details. The 
legs, and especially the great claws, are beautifully marked 
and sculptured, the swimming crabs being alike in colour 
and form singularly beautiful creatures. 

The largest species is the velvet-crab (Portunus puber\ 
which owes its name to the dense coat of fine hair which 
covers the body. It is very rare on the East Coast, but is 
abundant on the South-west, where it occurs among weeds 
between tide-marks. 

There are numerous other species of swimming crabs, 


among which may be specially mentioned P. depurator, the 
wrinkled swimming crab, and P. marmoreus, a form with 

beautifully marbled 
carapace. The 
species are so nu- 
merous that it seems 
unnecessary here to 
give their distin- 
guishing features, 
especially as many 
of them are very 
local in their distri- 
bution. Swimming 
crabs are most fre- 
quently found on 
the shore thrown up 

Fm. 57. Portunus depurator, the wrinkled swimming V>v thp wavp<3 hnfc 
crab. Note the shape of the last pair of legs. . Dy * 8 . waves > P ut 

in certain localities, 

especially at the edge of rocks running out into the clear 
sand, it is not uncommon to find them in the living active 
condition. In the sandy pools the peculiar method of loco- 
motion may then be readily observed. A careful anatomical 
comparison with Carcinus should also be made. 

Of the last family of crabs, the Catometopa, or quadri- 
lateral crabs, one example only need be described. This is 
the very curious Pinnotheres pisum, the pea-crab, a very 
small crab found inside the shells of many bivalves, 
especially the horse-mussel (Mytilus modiolus), the oyster 
(Ostrea), the cockle (Cardium), and others. The peculiar 
habit has given rise to many curious superstitions, the 
present being one of the first cases known of what we 
now call " commensalism." The carapace is arched, almost 
circular, smooth and delicate, and in the female almost 
uncalcified. The males are smaller than the females, and 
have a projecting forehead, while that of the females is 
uniformly rounded. 

This concludes our brief survey of the true crabs, which, 
as we have seen, are the most specialised of the Decapod 
Crustacea. We have begun our survey of the Crustacea 
with the Decapods because they are the largest and most 
conspicuous forms, and because they illustrate so admirably 


the meaning of the evolution theory. All are constructed 
on fundamentally the same plan, but display almost infinite 
modification in detail. As already hinted in the preceding 
chapters, it is clear that while the ancestral forms, like the 
more primitive living forms, must have been free-swimming 
animals inhabiting open water, the tendency of all has been 
to acquire in many different ways the creeping habit, which 
is an adaptation to life on the sea-bottom. Further, some 
forms, like the swimming crabs, have secondarily re-acquired 
the power of swimming, but accomplish this by the modified 
legs, and not by the appendages of the tail as the primitive 
forms do. 

The motion of the more primitive swimming Decapods 
is very well worth study and is of much interest. It is 
perhaps most easily observed in some of the smaller prawns, 
which live well in confinement and require less space than 
the larger forms. When undisturbed their swimming is 
the perfection of graceful and apparently almost effortless 
movement. The tail-fan is kept expanded, and serves as a 
rudder to alter the direction of the movements as occasion 
may require ; it must also be of much use as a float, by its 
extent and lightness assisting to support the body in the 
water. The antennal scales, which are often large, no doubt 
also perform both functions. The propulsion of the body is 
effected by the movements of the anterior swimmerets, 
which by their constant motion can drive the body in any 
direction. Startle your prawn and you will find that it 
darts backwards or sideways by the sudden flexion of the 
mobile tail. It is, however, characteristic of the Natantia 
that their ordinary mode of movement is gentle swimming 
by means of the anterior five pairs of swimmerets. The 
creeping Decapods have lost this mode of motion, and 
though they retain in many cases the power of jerking 
themselves backward at a sudden alarm, their ordinary 
method of locomotion is a leisurely creeping. The anterior 
swimmerets may be retained, or may be largely aborted, 
but they are never strong enough to propel the heavy body. 
Beginning with this prime distinction of habit, it is easy 
to deduce the structural characters of the two sets, and it is 
of very much interest to note how the minute differences 
between Crustacea, such as prawn, lobster, and crab, are 


associated with their differences in habit and mode of life. 
The intimate nature of the association is often easier to 
demonstrate in the Crustacea than in other groups, and 
adds much of their interest to them. 

Though the chapters on the Decapod Crustacea have 
spun themselves out to an unreasonable length, it is not 
easy to tear ourselves away from so fascinating a group. 
Two subjects have not yet been spoken of, and must just 
be touched on. 

One of these is the moult, too interesting a phenomenon 
of Crustacean life to be omitted. We have already dwelt 
upon the characteristic Crustacean cuticle, or coat, and its 
advantages as a defence. It has, however, the correlated 
disadvantage that it periodically becomes too small for its 
owner, and has to be cast and renewed. This occurs in all 
Crustacea, but is perhaps best and most frequently seen in 
the edible crab. If you search diligently under stones far 
out on the rocks, you will certainly sooner or later come 
across an edible crab in a sluggish apathetic condition. 
Watch it, and you will see the whole of the shell split off 
at the insertion of the legs, and thrown aside, snowing 
beneath it the new coat, very bright in colour but perfectly 
soft to the touch. Little by little the crab also extricates 
himself from the rest of his coat, pulling his claws slowly 
from their envelope, and gradually pushing the discarded 
shell away from him. Pick this up, and you will find that 
it is complete in every detail; not only is the covering of 
every appendage (even the most minute) fully represented, 
but the covering of the eyes, of the gills, nay, even the 
lining of the stomach is there. Turn to your soft, helpless 
crab, and you will see a stranger sight still : the crab which 
has just come out of the shell you hold in your hand is 
now bigger, is probably what will seem to you very much 
bigger than that shell. If, as one is often very apt to do, 
you have placed the crab when first seen in a bottle for 
transport, you will find that what went in easily will by no 
means come out without injury. The meaning of which 
strange fact is that as the new coat does not stay soft for 
long, the crab must hasten to get all the growing- done 
possible in the short time at its disposal. But growth is 
a slow process, so it distends its tissues with water to en- 


sure the new shell being large enough to allow of sub- 
sequent growth. Try to boil and eat a "soft" crab, and 
you will speedily realise the condition of affairs. The 
process of moulting in a large crab is to be counted as one 
of the most impressive of the phenomena to be witnessed 
on the shore, and may often be watched by a close observer. 
During and after the moult the crab is absolutely helpless, 
and until the shell grows hard again is at the mercy of 
every foe. The crab realises clearly its 'helpless condition, 
and always seeks shelter in some nook or cranny of the 
rocks. Even there, however, it is not always safe, and is 
attacked by members both of its own and other species, 
who greatly appreciate the succulent morsel. Moulting is 
in consequence a process full of risk and danger to all 
Crustacea, but it is the price which has to be paid for the 
advantage of a coat of armour. 

Moulting occurs in all Crustacea, and many times in the 
life of each individual. The cast coats of the different 
species are always abundant about the shore rocks, and are 
often mistaken for dead crabs. They are always interesting 
and worth study, and can be recommended to those who 
have scruples about killing animals for dissection purposes. 

In still one other respect the Crustacea are of great 
interest. This is in regard to their development, which is 
markedly indirect, the young being usually very unlike the 
adults. Examine a female Mysis, or opossum-shrimp (see 
p. 209), with young in her brood pouch, and you will find 
that the young are in most respects similar to the parents. 
This is one of the exceptional cases where the development 
is direct, and without distinct metamorphosis. It is other- 
wise with the majority of the Crustacea. In the crabs, for 
instance, the eggs are carried about by the mother only till 
they hatch, and the larvae when hatched (see Fig. 92) are 
very different from the mother. They are minute, trans- 
parent creatures, colourless save for the eyes, with quaintly 
shaped body furnished with long spines and few appendages. 
Such embryos are called zoeas, and their relation to the 
adult crab was for long unknown. The zoea stage of the 
common shore crab is to be found in vast numbers on the 
surface of the sea in autumn, but is more likely to be got 
by tow-netting than in rock pools. The zoea grows and 



moults and becomes converted into the megalopa, a form 
much more like a crab than the zoea, but differing markedly 
from crabs in the presence of a long, mobile abdomen, 
capable of being used in locomotion. The megalopa is the 
stage of transition from the free-swimming zoea, whose 
habitat is the open sea, to the creeping crab, whose habitat 
is the sea-floor. Its special interest lies in the fact that 
while the zoea swims by means of its thoracic appendages, 
as do some of the' lower Crustacea, the megalopa can swim 
with its tail like a long-tailed Decapod. For a full dis- 
cussion of development of the Crustacea 
reference must be made to the text- 
books, but the study of a living 
megalopa will give you a more real and 
vivid appreciation of the process than 
the clearest and best description. The 
megalopa stage of our common crabs 
may often be found among weeds in 
the rock pools. 

When found, place your specimens 
in a saucer of clean water, and examine 
of tail and body, the w ith a lens. If you have obtained 

ten legs, the rostrum . . ,.~, ^ , .,, 

between the eyes, and specimens of different ages you will 
tail SV After e B e ro S ok n the no ^ ce now some move like a Galathea 
by rapid jerks of the tail, how others 
alternate between this and creeping like a crab, while others, 
again, confine themselves almost entirely to the latter form 
of motion. The sight is one which you will probably mark 
as forming an epoch in your observations of shore animals. 
The fact in itself is a 
mere trifle perhaps, but 
it is one of those ap- 
parently trifling pieces of 
observation which seem 
to suddenly illumine 
days of patient, but ap- 
parently fruitless, study. 
Later the little mega- 
lopa tucks in its tail, FlQ 59._My 8 is stage of Norway lobster (Neph- 
UnderCOeS Certain minor rops). Notice that the biramose legs of the 
. , i larva are in process of transition into the 

alterations, and becomes uniramose legs of the adult. After Sars. 



converted into the young crab. This is merely one, and by 
no means one of the most complex, of the life-histories of 
the Crustacea, but it is one which can generally be easily 
studied. In Fig. 59 another larval stage, one which is 
common among long-tailed Decapods, is represented. Its 
great interest lies in the resemblance to the opossum-shrimp, 
especially as regards the shape of the legs. 



II. REPTANTIA (see p. 163), Brachyura, or crabs in the narrow 
sense, including forms with short antenna, which, like the eyes and 
an tommies, are placed in sockets. 

Carapace triangular with \ 1. Fam. Oxyrhyneha 
rostrum, legs long . / (spider-crabs). 

Carapace broad, arched 
in front, and narrow 

d l 
w V 2. 

Fam. Cyclometopa. 

1. Fam. Oxyrhyneha. 

Chelipeds not 
markedly dif- ^ 
ferent from 
other legs . 

Chelipeds much 
shorter and 
stouter than 
other legs, 1 
which are 
very slender 

Rostrum with diver- / Maia 
. \ 

gent horns Maia 

Rostrum with conver- 
gent horns, hollowed \ 

squinado, with 
prickly body. 
In H. araneus the cara- 
P a f? " oi contra cted 
behmd the P~t-orbital 
. T Processes 
I In H. coarctalus it is con- 
tracted behind these. 

Carapace sub-triangu- 
lar, nearly as broad 
as long, orbits elon- 
gated Inaclius 

Carapace an elongated 
triangle with long 
rostrum Steno- 

Between tide-marks I. do- 
rhynchus, with three 
spines on the gastric 
region, is the only 
species found. 

Between tide-marks oc- 
curs S. phalangium, 
in which the rostrum 
is shorter than the 
stalk of the antennae. 



2. Fam. Cyclometopa. 

a. Walking legs all with thin\ Carapace with nine lobes Cancer 
pointed terminal segments/ pagurus, or edible crab. 

long as \ P. variegatus is only 
rtumnus J species. 
Last segment of ^ 
fifth legs only ! Only species is 
expanded j 0. mcenas. 
Carcinus . J 
Penultimate seg-^ ,.- 
ment expanded I m ^ S P 6C1 S > e ^' 
as well as last f ^-P^e^Pmar- 
, -Portunus J moreus > etc ' 

3. Fam. Catometopa. 

v/ai ct ucbL/c ao 

broad Po 

Last pair of 

walking legs 

with ex-- 
panded tin- 
like ending. 

broader - 
than long 


I. Natantia swimming forms with compressed bodies and functional 
swimmerets ; e.g. prawns and shrimps (Chap. VIII. ). Fam. Carididte. 

II. Reptantia creeping forms, sometimes with long tails (Macrura), 
e.g. lobster and crayfish ; sometimes with inturned tails (Brachyura), 
e.g. crabs ; intermediate forms also occur. The following families 
are included : 

(1) AstacidjB, lobster and Norway lobster. 

(2) Palinuridse, rock -lobster. 

(3) Porcellanidse, the lobster-like Galatheas and the crab -like 


(4) PaguridjB, the hermit-crabs. 

(5) Lithodidae, the stone-crab, with large incompletely calcified 


(6) Corystidse, the masked crab and the circular crab ; the latter 

is sometimes placed in the family Cyclometopa. 

(7) Oxyrhyncha, the spider-crabs, apt to be confused with the 


(8) Cyclometopa, the shore crab, swimming crabs, and edible crab. 

(9) Catometopa, the pea-crab, and a few other southern forms. 


Generally speaking it may be said that the crabs increase in number 
'in the British area as one passes southward. Exceptions to this rule 
are the interesting stone-crab, a northern species, and the two species 
of Hyas. These last are not absent from the South-west of England, 
but they are not nearly so abundant there as in the North. On the 
other hand, the rocky coasts of Devon and Cornwall produce Maia 
squinado, especially abundant in Cornwall, the velvet-crab between 
tide-marks, and a number of other interesting and peculiar forms of 
which no mention has been made here. The shore crab, the edible 
crab, the numerous species of Portunus apart from the velvet-crab, 
occur at all parts of the coast. 



The opossum-shrimp and its allies Sessile-eyed Crustacea Structure 
of Isopods The Amphipoda Characters and habits of sand- 
hoppers Structure of Caprella The lower Crustacea Structure 
and habits of acorn-shells and barnacles Crustacean parasites 
Sea-spiders Their zoological interest. 

WHILE searching for shrimps and prawns, you are 
certain sooner or later to encounter some little shrimp- 
like creatures of singularly beautiful appearance. Far out 
on the rocks, in clear pools floored with silver sand, you 
will find them swimming with outspread eyes, and bodies of 
crystal clearness. Turn to the shallower pools lined with 
green weed and you will find similar forms, but here of the 
same pale green as their surroundings. Again, if you push 
aside the great blades of 
Laminaria, you will see dart- 
ing out from beneath them 
in shoals the same little crea- 
tures, but now of a deep 
brown tint. This is My sis 
flexuosa, sometimes called 
chamceleon from its Protean 
tints, and chain seleon-like in Flo . eo.-Opossum-shrimp (Mysis frx- 

its power of colour change. 

a -t, , t 

bwitt swimmers as they are, 
they are easily caught, and, though difficult to keep in an 
aquarium, they are well worth study. Collect a good 
handful, and put them with plenty of clean water in a glass 
jar. You will then have no difficulty in seeing that in 
many respects they resemble shrimps and prawns very 

P 209 

uosa). Female specimen, showing brood 
pouch between the posterior legs. 


closely (Fig. 60). Like them they have an anterior region, 
not obviously segmented and covered by a shield; a tail 
region divided into segments and ending in a powerful 
tail fin, and long feelers colourless in the living animal, 
and bearing a large scale or squame at their bases. They 
differ from shrimps, however, in that they seem to have 
far more legs, and in that many of them have a pouch 
attached to the posterior legs, as is shown in the ac- 
companying figure. These are the females, and when 
adult the pouch will be found to contain developing eggs. 
The eggs are placed in the pouch when laid, and are 
carried about by the mother. The members of the order 
to which Mysis belongs are all very good swimmers, well 
adapted for life out in the open sea, but, as happens with 
so many marine animals, the females come inshore at the 
breeding season. This is partly, no doubt, for the sake 
of the young when hatched, but probably, in other cases, 
because the weight of the eggs or young must greatly 
diminish the swimming power of the mother. Your speci- 
mens are almost certain to be all females, and a very brief 
experience will be sufficient to teach you that the large 
mature specimens are so sensitive to unfavourable condi- 
tions, that they will not readily live in confinement. In a 
very short time they lose their lovely tints, become dull and 
opaque, and drop to the bottom of the jar. You will find 
that this delicacy of egg-carrying females is common in the 
Crustacea, and it is profoundly interesting, for it shows how 
great must be the advantage of the habit of carrying about 
the eggs, if it can persist against such heavy odds. There 
are, indeed, few subjects more interesting than the reproduc- 
tive phenomena of shore animals. 

Before proceeding to the examination of your dead 
specimens, you should examine the living ones under a 
lens in a watch-glass filled with sea-water. Whatever be 
the prevailing tint, and it varies much, you will find the 
dorsal surface covered with the same beautiful branched 
pigment cells seen in the shrimp. They are here black in 
colour and are often arranged segmentally, one for each 
segment. This is indicated in the figure. The rest of the 
body may be green, or brown, or transparent, but the 
anterior region is almost always delicately suffused with 


pink, especially about the antennae. You will notice also 
the large, very movable eyes, usually outspread laterally, 
but capable of much freedom of movement. Also the 
curious bend in the middle of the body, which gives rise 
to the name flexuosa, and has at times almost the look of a 
deformity. The larger specimens will be found to be over 
an inch in length, but many are much smaller. With the 
lens there is no difficulty in making out that there are eight 
pairs of legs, very similar to one another, and that all of 
them consist of two branches. It is on account of this and 
of some other characters that Mi/sis is included in the order 
Schizopoda, or "split-footed," as contrasted with the Deca- 
poda, or Crustacea with ten legs, already described. The 
Schizopods are even more purely swimmers than the Natantia 
among Decapods; they have no walking legs, strictly speaking, 
and their eight pairs of thoracic legs resemble one another 
very closely. 

The My sis described above is by far the commonest 
member of its order on the shore, for the great majority 
of its relatives live in the open sea, but there are a few 
other nearly related forms which occur more sparingly along 
with Mysis flexuosa^ or are occasionally found far out at 
exceptionally low tides. All these belong to the family 
MysidaB, and resemble one another so closely that their 
discrimination requires some care. Those who are fond of 
species work will find Mysidae peculiarly fascinating, while 
others are recommended to rest content with Mysis flexuosa. 
We shall describe one or two representative species only. 

To begin with the large Mysis flexuosa. We have already 
seen that it belongs to the order Schizopoda; it further 
belongs to the family Mysidae because of the following 
characters. Its eight pairs of thoracic limbs are similar 
but not identical, for the first two have a masticatory 
process at their base, and the first has also a flat vibratile 
appendage. Some of the posterior thoracic limbs bear 
somewhat similar appendages, which here, however, are 
apposed so as to form the brood pouch in the female. Gills 
are entirely absent. There is much difference between the 
sexes, especially as regards the abdominal appendages, for 
these, except the last pair, are well developed in the male 
and rudimentary in the female. The inner branches of the 



tail fins bear round auditory organs (o in Fig. 61), for My sis 
has ears in its tail. The last five segments of the thorax 
are more or less movable, not fused together as in shrimps. 
All the Schizopods you are likely to find on the shore 
belong to this family. It is divided into a great number of 
sub-families, chiefly on account of the varying structure of 
antennas and telson, and the sub-families contain numerous 
genera, but it will be sufficient for our purpose to retain the 
genus Mysis in its old sense. For further details reference 
should be made to Canon Norman's papers (see books of 
reference at end). 

If you have succeeded in laying out the thoracic limbs 

FIG. &1.A, head, and B, part of tail of Mysis. A shows 
the eyes (e), the scale (s), and part of the flagellum of 
the right antenna, and the two antennules (a). B shows 
the telson (t)and the left terminal swimmeret, with the 
ear (o) in the inner branch. After Bell. 

of Mysis flexuosa in a row, and demonstrating the other 
characters of the family to your satisfaction, you will find 
no further difficulty in studying its specific characters. 
Besides the points already noted it is distinguished by the 
following peculiarities. First, the length of the antennal 
scale (s in Fig. 61). To see this clearly, float your dead 
Mysis in water the lid of a white ointment jar makes a 
good dissecting dish and observe under a lens. You will 
then see clearly the antennae with their long flagella and 
stout scales (s), and the shorter antennules (a), each with 
a three-pointed stalk and two feelers. In Mysis flexuosa 
you will find that the scale of the antennas is narrow and 
very long, twice as long as the stalk of the antennules ; it 
is without bristles (setae) on its outer margin, and that 
margin terminates in a distinct spine ; all these points are 
clearly shown in Fig. 61, A, which also shows the eyes (e). 


Turn now to the telson, or last segment of the body, and 
you will find that this is deeply cleft at its tip (t in Fig. 61), 
and bears twenty-one to twenty-seven spines on either side. 
Note at the same time the curious ear (o) in the swimmeret. 
Minute points of no importance you will probably think 
these, but your respect for them will probably increase 
when you examine specimen after specimen and find them 
constant, true indices of those subtle undefinable characters 
which make up the species M. flexuosa. There are few 
more striking illustrations of what is meant by the con- 
stancy of nature, than the characters of nearly related 
species like those of the genus Mysis. In many cases the 
species is defined by the relative size of two structures, or 
by the number of spines borne by an organ. What invisible 
force is it that limits the growth of the antennal scale in 
M. flexuosa when it is twice as long as the stalk of the 
antennule, and allows that of M. vulgaris to grow till it is 
four times as long? Why should the latter never have 
more than twenty-five spines on its telson when the former 
may have twenty-seven ? When these and similar questions 
crowd upon you, then the fascinations of species work will 
become clear. One would not of course deny the existence 
of variability here, as elsewhere, but very little species work 
will serve to convince you of the essential constancy upon 
which the variability is superimposed. 

The characters given above will be found sufficient to 
identify M. flexuosa. Another species, smaller in size and 
much less common, may be sometimes found with it. This 
is M. vulgaris, which, though occasionally found in rock 
pools, is typically an inhabitant of tidal rivers and estuaries. 
It is most likely to be found in the pools left by the ebbing 
tide on those mud flats which in Northumberland are called 
"slakes"; or sometimes occurs in myriads at the edges of 
tidal rivers. This species may be recognised by the fact 
that the antennal scale has no spine, is furnished with setse 
all round, and is four times as long as the peduncle of the 
antennules. The telson is not cleft, and ends in four spines. 

There are a great many other species of Mysis found 
more or less commonly on our shores, but for these reference 
must be made to Canon Norman's papers. I shall mention 
one more only, which I have found to be not infrequent on 


the East Coast, and which is interesting on account of its 
colour. This is My sis lamornce, a delicate little creature 
not much more than one-third of an inch long, and wholly 
or partially of a bright red colour. It is often in large 
part perfectly transparent, but is suffused with scarlet and 
bears bright scarlet eggs. It may be found under stones 
far out on the rocks, and may be recognised by the very 
large eyes borne on short stalks, and by the fact that the 
antennal scale is the same length as the peduncle of the 
antennule, and that the telson is cleft for one-quarter of 
its length, without spines in its upper portion, and furnished 
distally with six to twelve at either side. The distribution 
of this species in Europe is wide, for it ranges from Lofoten, 
on the coast of Norway, through the Mediterranean to the 
Black Sea. The colour is also worth notice, for bright red 
is common in deep-sea Crustacea and in pelagic forms, but 
is rare in those found near the shore. 

In the above species the specimens found are much more 
likely to be females than males. When found the males 
may be recognised by the absence of the brood pouch, the 
slimmer form, and the nature of the swimmerets. The 
third and fourth of these are much better developed than 
in the females, the fourth being furnished with a long 
many-jointed whip-like structure. 

We shall not here describe any other of the British 
species of Mysis, but a not uncommon form which is now 
referred to another genus is worth notice. This is Siriella 
armata, found in rock pools in company with Mysis 
flezuosa, but distinguished by its smaller size and more 
delicate appearance. It is referred to a different genus 
because the outer branch of the last swimmerets is divided 
into two joints, the carapace is prolonged anteriorly into a 
long rostrum instead of ending in a blunt point, and all the 
swimmerets of the male except the first are well developed, 
some of them being furnished with a curiously coiled pro- 
cess. In the species named the rostrum is as long as the 
antennal scale, both being slightly shorter than the stalk of 
the antennules. The telson is very long, not cleft, slightly 
constricted at its base, its margin being furnished with a 
few short spines placed between longer ones. This species 
is difficult to distinguish from other closely related species 


of the genus, but it will be found that the telson ends in 
four minute spines, separated by two setae from the large 
lateral spines. 

The above may serve as examples of our British Mysidse, 
and will show how relatively small are the differences which 
separate the species and even the genera, compared with 
the differences between the sexes. When to this is added 
the fact that many of them only appear sporadically and 
locally on our coasts, it will be readily understood that not 
only have males and females been commonly referred to 
different genera, but also that the different specialists in the 
group have held very various views as to what should con- 
stitute generic or specific distinctness. Consequently there 
is great confusion as to the names of the different forms. 
For example, a form described in Bell's Crustacea under the 
name of TTiemisto brevispinosa appears to be only the male 
of My sis flexuosa. 

The other Schizopods lie somewhat outside our range, for 
they inhabit the open sea. The interest of the order as 
a whole lies in the general resemblance to the Natant 
Decapods, and the detailed similarity to the larvae of many 
of the Decapods (see Fig. 59). The beauty of the form 
and colour, the activity, the frequent extraordinary abund- 
ance of individuals, and the habit of swimming in shoals 
should also be noticed. 

The orders Decapoda and Schizopoda, whatever their 
other differences, both include forms having stalked eyes 
and a dorsal shield or shell, but there are other shore 
Crustacea of considerable size and complexity in which the 
eyes are sessile and the dorsal shield is absent. These fall 
into two sets: (1) the Isopoda, forms more or less like the 
common "slater," or wood-louse, with flattened bodies, and 
(2) the Amphipoda, or sand-hoppers, whose bodies are com- 
pressed, and who usually have six abdominal legs, three 
directed forwards and three backwards. We shall not 
enter into either of these orders in detail, for their mem- 
bers are not as a rule attractive to most people, and are 
often difficult of identification. 

As an example of the Isopoda we may take a not un- 
common and somewhat interesting form known as Idotea 
tricuspidata. It is usually found clinging to weed, especially 


Fucus, by its numerous sharp-clawed legs, and is extra- 
ordinarily variable in colour. Usually brown or brownish, 
it is sometimes tinted with yellow, red, or green, sometimes 
spotted or striped with darker colour. The length varies 
from three-quarters of an inch to an inch or more, and the 
flattened body makes the little creature very inconspicuous. 
As in other members of the order, the number of rings 
in the body is primarily the same as in Decapoda, but the 
body is distinctly divided into three regions, of which the 
thoracic is the most conspicuous. The first thoracic segment 
is fused to the head, so that the thorax 
appears only to possess seven rings ; the 
abdominal segments are in part fused. 
The head bears two pairs of antennae, 
consisting of simple flagella; of these 
the outer are half as long as the body. 
There are seven pairs of similar thoracic 
legs, corresponding to the seven free 
thoracic segments. Over the surface of 
the abdomen there is a triangular tail- 
shield which covers all except the two 
first rings. The five anterior abdominal 
FIO. 62. idotea tricuspi- appendages are converted into thin respi- 

data. In part from Bate r i A ,-, ,1 < . 

and Westwood. ratory plates, the sixth pair forms two 

strong valves which cover over these 
thin plates. In life the valves are in constant motion, 
opening and shutting to facilitate the passage of water 
over these curious breathing organs, which replace the gills 
of the Decapods. A careful dissection of Idotea is easily 
made, and will be found very profitable. 

The Amphipoda are most typically represented by the 
sand-hoppers, which swarm everywhere over the damp sand, 
assembling in myriads about decaying substances thrown on 
the beach, and perforating the dry sand above high-tide 
mark in all directions with their burrows. They are the 
great scavengers of the shore, sometimes within a few hours 
reducing dead birds of considerable size to the condition of 
skeletons. On the rocks their place is taken by other forms 
equally abundant, and of similar habit. 

The common sand-hopper is Talitrus saltator. Like its 
allies, it presents a general resemblance to the Isopods, but 


differs in the compressed shape, and in the fact that the 
thoracic appendages bear breathing organs, while the 
abdominal are used for swimming and jumping. As special 
characters are to be noticed the absence of the anterior 
antennae (antennules), and the great length of the posterior. 
Of the seven thoracic legs the first pair are larger than the 
second. The first three abdominal appendages are turned 
forwards, and are used for swimming; the last three are 
turned backwards, and are used for jumping. The colour, 
as everyone knows, is a peculiarly glassy yellowish white, or 
occasionally a dark dirty tint. 

Under stones in the rock pools the true sand-hopper is 
replaced by swarms of another little creature of similar size. 
This is Gammarus locusta (see 
Fig. 63), the great scavenger of 
the rock pools, as the sand- 
hopper is of the shore. It 
is easily distinguished from the 
latter by the fact that the an- 
terior antenna (antennules) are 
well developed, and have two 
filaments each. When suddenly 
uncovered by the removal of the 

Stone Under which it has been FIG. 63. Gammarus locusta. Note 
i /-v i ! , the two pairs of feelers and the 

lying, GammarUS exhibits a number of legs, of which there 

curious sidelong movement, which J en pairs belon g in g to the 
seems to combine the maximum 

effort with the minimum result. If you shake out a bunch 
of weed in water, however, you will find that the little 
animals can swim swiftly enough. 

Another somewhat interesting shore Amphipod is Amphi- 
thoe podoceroides, which makes nests of weeds under stones. 
The nests are often of considerable length, and very neatly 
woven, and are a source of much disappointment to many a 
young shore naturalist. The nest is found with joy, and 
torn open by careful fingers, eagerly expectant of a prize, 
when instead out shoots the Amphithoe, or oftener, perhaps, 
two of them, male and female together. Why they should 
be a disappointment perhaps is not obvious, but it is an un- 
doubted fact that most people cannot carry their enthusiasm 
as far as Amphipods. The species named reaches a length 


of about three-quarters of an inch, and is usually olive- 
green in colour, minutely speckled with black spots. The 
inferior antennas, or antenna? proper, are shorter and stouter 
than the superior, and the last pair of jumping legs are 
furnished with hooks. 

Before leaving the Amphipods one other set of forms 
must be noticed. These, typically represented by the 
species of Caprella, are very different from the rest, being 
both curious and beautiful, but unfortunately not very 
abundant or very easy to find. Study closely a rock pool 
lined with red seaweed, and you may see a slender thread- 
like creature, probably rather over half an inch in length, 
which attaches itself to the weed by its long back legs, and 
sways back and forwards in the water. The tint is exactly 
that of the weed, and the swaying motion so similar to that 
produced by currents of water, that it is exceedingly 
difficult to distinguish the little organism. Disturb it, and 
it will swim rapidly through the water by suddenly con- 
tracting and straightening the body, or travel over the 
surface of the weed by alternately fixing the opposite ends 
of the body like a "looping caterpillar." It is unfortunate 
that we have no common English name for these interesting 
and curious little creatures. One or two should be taken 

home for careful exam- 
ination under a lens. 
It will then be found 
that the second thoracic 
segment is fused to the 
head as well as the 
first, so that there are 
only six free segments. 
In the figure the first 
and sixth are num- 
bered. The abdomen 

Fio. 64. Caprella Unearis. The letters are (ttb) is greatly reduced, 
explained in the text. and at most bearg mQTQ 

rudiments of appendages. The head bears two pairs of 
similar antennae, and on account of the fusion of segments 
the first pair of legs appears to arise from it. The second 
pair of legs is large and sub-chelate, as in some shrimps 
that is, the last segment can be bent down on the second 


last, to form a kind of forceps. There are no true append- 
ages on the next two segments, but merely two expanded 
respiratory plates (rp). In the mature female these seg- 
ments also give rise to four incurved lamellae, which together 
form a brood pouch containing the transparent eggs. The 
last three thoracic segments each bear a pair of well- 
developed legs directed backwards. The abdomen (ab) is 
reduced to a mere knob. There are several species which 
are not very easy to distinguish from one another ; the 
commonest is, perhaps, Caprella tuberculata. 

We have given very few examples of these sessile-eyed 
Crustacea, because they are not of great general interest, and 
those who are desirous of pursuing the subject further will 
find Bate and Westwood's British Sessile-eyed Crustacea a 
comprehensive and readily accessible work. 

The Amphipods and Isopods do not complete the Crus- 
tacea, for there are in addition a considerable number of 
other orders, all comprised in the Entomostraca or lower 
Crustacea, as contrasted with Amphipods, Isopods, Schizo- 
pods, and Decapods, which are all included in the Mala- 
costraca or higher Crustacea. The Entomostraca are usually 
of small size, consist of a variable number of segments, and 
have no gizzard or gastric mill. A large number of them are 
parasites, often very degraded parasites, and many others 
are water fleas, such as may be found in any pool. The 
latter form an important part of the food of fishes and other 
marine animals, but cannot be considered in detail here. 
Of the Entomostraca we shall consider only four common 
examples, all belonging to the order Cirripedia. 

Our first example is, perhaps, the most abundant animal 
of all on many shores. This is Balanus balanoides, the 
common acorn -shell, often so abundant as to whiten the 
shore rocks, and also covering shells, posts, and almost every 
available surface within tide-marks. At low tide the little 
white cones look dead and desolate enough ; but if you 
watch a mass of them exposed to the action of the incoming 
water, you will find the scene changed indeed. As the 
white water breaks foaming over the rock, and trickles off 
more slowly, you will see each tiny shell open and protrude 
a delicate fringe, which opens and closes in frantic haste as 
if its owner were aware that the water would soon be gone. 


There are few more beautiful sights than a rock covered 
with acorn-shells exposed to dashing breakers. The moist 
oxygenated air seems to excite the little creatures, and they 
open almost before the first drops touch them, and keep up 
their vigorous fishing till the last drop trickles off the rock. 
The sight of those myriads of little fans in action is one not 
soon to be forgotten. The acorn-shells have another interest 
in their history. They were long thought to be molluscs, 
and it was not till, in 1830, their development was fully 
worked out by J. Vaughan Thompson, that their true 
position was understood. 

The details of the anatomy are somewhat beyond our 
scope, but we may notice that the segmentation of the 
body is quite indistinct, and that it is clothed in a fold of 
skin, which secretes a shell of limy plates. The limy plates 
consist of a ring fixed to the rock and inclosing the body, 
and a movable lid or operculum, formed of separate plates, 
which open to allow the protrusion of the six pairs of two- 
branched jointed feet. The commonest species is Balanus 
balanoides, but there are several others on our shores. 

An even more curious creature is the related ship-barnacle, 
Lepas anatifera, occasionally found on wreckage on the 
shore. It has a long fleshy stalk, usually several inches in 
length, bearing at its tip a complicated whitish shell, and 
attached to floating wood by the other end. The shell is 
formed of five separate plates, and in life is continually 
opening at its tip to allow the six pairs of jointed legs to 
be protruded. The ship-barnacle has some antiquarian 
interest, because it was thought by the old authors to have 
some connection with the Bernicle Goose. The old herbalist 
Gerard described the young geese hatching out of the 
barnacles under the influence of sunlight, but though there 
are very many strange things about these curious creatures 
there is nothing quite so strange as this. 

Two more of the lower Crustacea must be briefly described, 
not because they can be studied with any degree of success, 
but because they are certain to be encountered. These are 
two parasites, which are true Crustacea in their youth, but 
in adult life display no trace of Crustacean characters. One, 
PeMogaster paguri, is very common on the hermit-crab, the 
other, Sacculina carcini, is found on the abdomen of the 


shore crab, or occasionally on the swimming-crabs. If you 
keep hermit-crabs even for a short period in a crowded 
collecting-bottle, they very speedily show their discomfort 
by quitting their shells. As they trail the lank abdomen 
behind them, you will notice in one or two cases a large 
rounded cylindrical body of yellowish colour attached to its 
under surface. This is the parasite, and its only distinct 
structural peculiarity is the reproductive orifice at the broader 
end of the cylinder. Dissect a dead hermit, and you will 
find ramifying through its abdomen a system of fine roots, 
by means of which the parasite feeds itself. It has no 
mouth, no alimentary canal, no appendages, and is chiefly a 
mere sac of eggs. Much less conspicuous is the rounded 
Sacculina on the abdomen of crabs, for it is partly concealed 
by the inturned tail of the crab. Its structure is similar, 
except that the reproductive orifice is in the middle instead 
of at one end. 

One other small group may be considered here in con- 
nection with the Crustacea, for though its littoral members 
are few in number, they are very 
common, and the group itself is one 
of great interest. This is the Pycno- 
gonida, or sea-spiders, including small 
long-legged, spidery creatures com- 
mon under stones on the shore. Two 
are very common; one (Pycnogonum 
littorale, see Fig. 65) occurs under 
slightly muddy stones, and is a dirty FIG. 65. Sea-spider (Pycno. 
yellowish flattened creature with four 9 num morale ^ 

pairs of stout knobbed legs, and a massive trunk prolonged 
forwards into a large cone-shaped proboscis, and bearing 
four brownish eyes on its dorsal surface. It is the most 
sluggish and leisurely of creatures, moving, when it does 
move, by slowly lifting one after the other its eight clawed 
legs. The other common form is more attractive both 
in tint and in shape. It is bright pink in colour, with 
long slender legs about three times the length of the 
body, and ending in long claws. In addition to the eight 
legs which it possesses in common with the preceding, it 
has a pair of short chelate appendages about the mouth, 
while the male, as in the preceding form, has two very 


slender appendages used for carrying the eggs. This pretty 
little creature rejoices in the dreadful name of Phoxichili- 
dium femoratum, and is to be found not uncommonly under 
stones or clambering over weeds between tide-marks. 

Other forms often occur in numbers on weeds cast ashore 
by storms. These are species of Nyiftphon, white or pinkish 
in colour, and not unlike the last in appearance, but with 
even more slender filiform legs, three or four times as long 
as the body. They differ from the preceding in having, in 
both sexes, three appendages in front of the first pair of 
legs. Beside the mouth, as in Phoxichilidium, are two 
small chelate limbs, behind these two pairs of slender 
appendages, the first with four or five joints, the second 
with nine. The first two pairs of appendages are used in 
connection with food catching; the third in the male, as 
in other Pycnogonids, carries the eggs, while in the female 
they are functionless. The remaining four pairs function 
as organs of locomotion in both sexes. This is the typical 
condition of the appendages, from which the common 
Pyenogonum littorale diverges widely. 

It is hardly necessary for us here to consider in detail the 
special characters of these curious creatures, but we may 
just note that their interest lies in great part in the fact 
that their systematic position is very uncertain. The body 
and limbs are segmented; they are undoubted Arthropods, 
but the body is divided into three regions unsegmented 
proboscis, trunk of four segments, and unsegmented abdomen, 
and there are no antenna? or gills ; a connection with the 
Crustacea is therefore not obvious. Of terrestrial Arthro- 
pods spiders seem to resemble them most in the absence of 
antennae and the presence of four pairs of legs, but spiders 
have two appendages only in front of the first walking leg, 
and sea- spiders may, as we have seen, possess three. Their 
position is thus wholly doubtful, and the question of their 
relationships unsolved. 

One other point of interest is found in the fact that, as 
in the sea-horse among fishes, it is the male and not the 
female which carries about the unhatched eggs. In the 
Crustacea it is of course the females alone which do this. 
Insignificant as the sluggish sea-spiders may seem to be, 
they are thus not without points of interest. Nor are they 



always small, for a magnificent form of large size occurs in 
the Arctic Ocean, and with the Gorgon-headed starfish 
(Asteroplnjtori) and some other beautiful creatures, rewards 
the zeal of the investigator of that chilly sea. 

Order SCHIZOPODA. Crustacea with eight similar pairs of bi- 
ramose thoracic legs. 

Fam. MYSIDJB. Gills are absent. Auditory organ present in the 

Antennal scale twice as long 
as peduncle of antennae. 
Telson cleft M. flexuosa. 
Antennal scale three or four 
times as long as peduncle. 
Telson entire M. milgaris. 
Antennal scale same length 
as peduncle. Telson short, 
cleft for one-quarter its 
length, upper half without 
spines M. lamornce. 

Outer branch of uropods \ 
one-jointed, and fur- I ,, . 
nished with bristles on f Mysis 
its outer margin . . j 

Outer branch of uropods 
two-jointed, first joint 
with spines, but not 
bristles, on its outer 

- Siriella 

Antennal scale same length 
as rostrum S. armata. 


Sub-class MALACOSTRACA. Body with nineteen segments. 
Section A. Forms with stalked eyes. 
Order 1. DECAPODA (see p. 208). 
Order 2. SCHIZOPODA. Eight pairs of similar biramose feet. 

Fam. MYSID.E. Auditory organ in tail. 
Section B. Forms with sessile eyes. 
Order 1. ISOPODA. Body flattened, appendages of abdomen, 

respiratory plates. 
Only one form, Idotea tricuspidata, has been described 

in the text. 
Order 2. AMPHIPODA. Body compressed, abdomen usually with 

six pairs of legs. 

In the text three sandhopper-like forms have been 
described, as well as a member of the family 
Caprellidse, in which the abdomen is greatly 



Sub-class ENTOMOSTRACA. Body usually with few segments. 
Order CIRRIPEDIA, including parasitic (Sacculina), and degenerate 
sedentary forms (Balanus). 

There are very many other kinds of Crustacea, especially of Ento- 
mostraca, not alluded to in the previous chapters on account of their 
small size, or rarity, or absence from the shore. 


A small group of uncertain affinities. Four pairs of walking legs, 
abdomen rudimentary, without appendages. 

No other appendages 
except four pairs of 
legs in female, male 
with slender egg- 
bearing legs . 

Chelipeds present near 
mouth, in female no 
other appendages 
except the legs, in 
male egg - bearing 
legs as before 

Chelipeds and two 
other pairs of appen- 
dages near mouth in 
both sexes 

Legs stout and re- /-Colour yellowish 
latively short ! white P. lit- 
Pycnogonum . ^ lorale. 

( Legs about three 
Legs very slender I times as long as 
and long Phoxi- \ body. Colour 
chilidium . . \ pink P. femora- 

Legs very long and 
slender Nym- 
phon . 

ver well definecL 



General characters of the Mollusca An outline classification The 
Chitons, their habits and structure The common limpets Forms 
with coiled shells Their general characters Tops and periwinkles 
Species of periwinkles Some allied forms Carnivorous forms 
Whelks, purples, and their allies Their egg-capsules and develop- 
ment The cowry. 

HHHE Mollusca form a very large group, including animals 
_L which are usually well defined and easy to recognise. 
The fact that most possess a shell which is easy to study 
and to preserve has rendered them general favourites among 
those interested in shore animals. Probably, indeed, most 
people have at some period of their lives made collections 
of shells ; all know how beautiful in form and colour they 
often are. Interesting as shells are, however, it cannot be 
denied that as a whole the Mollusca are a group of con- 
siderable difficulty. The shells are much more external 
structures than the coats of the Crustacea, have a less 
intimate connection with the body, and are therefore not 
of much use as guides to affinities, except to a very general 
degree, while the study of the internal structure is not easy. 
It is a natural result of this, that while much has been 
written on the shells of Mollusca, their internal structure 
is still in many cases insufficiently known. 

Perhaps the easiest way to get a general notion of the 
structure of Molluscs is to begin with the study of some of 
the limpets. Knock off the rocks a f e w large specimens of 
the common limpet, and look for the largest specimen you 
can find of the little tortoise-shell limpet, or its relative 
the little pink limpet, to be found far out on the rocks 

Q 225 



among the great blades of Laminaria. Put your specimens 
in a glass jar filled with clean water, and examine the lower 
surface (see Fig. 66). Some of the points of structure we 
have already noticed : the muscular foot in the centre, used 
here, as in many Molluscs, as a creeping surface ; the head, 
separated from the foot by a constriction, and bearing mouth, 
horns or tentacles, and eyes; the mantle-fringe, or flap, 
hanging down at the sides of the body like a frill, and 
secreting the conical shell above. In the tortoise-shell, but 
not in the common limpet, there is a single plume, or gill, 
exserted when the animal walks. These points studied, 
drop your specimens for a few minutes into hot water or 
spirit, and then remove the shells by slipping a sharp-pointed 
knife round the sides of the animal. Detailed dissection is 
not easy, but some points can be readily made out. Notice 
that the mantle is arched in the 
head region, so that it there forms 
the roof of a small chamber 
the mantle-cavity, which in the 
tortoise-shell limpet contains the 
gill. The mantle-cavity is a very 
important structure, and you 
should take pains to assure your- 
self that it is outside the body- 
cavity, that it is equivalent to 
the gill-chamber of the Crustacea, 
and is formed by the downgrowth 
of the mantle-flap, a free fold of 
skin. One other structure is of 
great importance; this is the 
so-called tongue, or radula, a long, 
brownish thread, much longer 
than the animal, which lies folded up at the right side, and 
is very easily found. When examined with the lens it will 
be found to be covered with numerous rows of small teeth. 
By means of it the limpets mow down the sea-grass upon 
which they feed, but the carnivorous Molluscs use it as a 
drill to perforate the shell of other Molluscs. 

One other point must be noticed in regard to the anatomy 
of the limpet. The posterior opening of the food canal, 
instead of being at the end of the body, as one would 

rr g 

FIG. 66. Under surface of com- 
mon limpet (Patella vulgatd). 
mo, mouth; ma, mantle pro- 
longed into fine processes ; 
/, foot; g, respiratory region 
of mantle. 


naturally expect, is close to the head at the right side 
that is, the limpet is unsymmetrical, the organs being, as 
it were, twisted round to the right side. 

The division of the Molluscs to which the limpets belong 
is known as the Gasteropods. Gasteropods are usually 
characterised by the presence of a shell, sometimes conical, 
usually coiled, but at times absent. The mantle-fold is 
single, and overarches a cavity which usually contains a 
single gill ; but, as in Patella, this gill may be absent, when 
its function is taken on by the mantle-fold. The foot forms 
a flat surface used for creeping ; the head is distinct, bears 
tentacles and eyes, and within the mouth there is almost 
invariably a well -developed radula. The body is usually 
markedly unsymmetrical, but where the shell is absent it may 
exhibit an apparent symmetry. There are an extraordinary 
number of Gasteropods, living on land, in fresh water, and 
in the sea, the most familiar forms being those with coiled 
shells, such as whelks, periwinkles, snails, and so on. 

Contrasted in many respects with the Gasteropods are 
the Bivalves, or Lamellibranchs, such as oysters, clams, 
mussels, cockles, etc. One may think of them in relation 
to Gasteropods in this way. Suppose in a limpet the body 
were to be greatly compressed laterally, the simple conical 
shell, one might suppose, would yield to the pressure so as 
to divide into two valves united by a hinge; the foot would 
lose its creeping surface and become narrow and compressed, 
the mantle-flap would grow downwards at each side, and, in 
conformity with the two-valved shell, would become double 
instead of single. If we suppose that at the same time 
the separate head, the tentacles, the eyes, and the radula 
were to be lost, symmetry to be acquired, and a second gill 
to appear, we should have roughly indicated the chief points 
of difference between Gastercpod and Lamellibranch. The 
latter are much more sedentary than the former, which 
usually live buried in sand or mud, and show fewer varia- 
tions in structure. All feed on microscopic food particles 
in the water, and have large flat plate-like gills, whence 
the name of Lamellibranch, and have a double shell, whence 
the alternative name of Bivalve. 

The third great set of Mollusca includes the active pre- 
daceous cuttles, which are known as Cephalopoda. In 


them the foot has grown up round the mouth, and is split 
up into "arms" furnished with suckers. Except in the 
pearly nautilus of the Pacific, there is no external shell, 
and the structure is in many respects strangely modified. 
Most of the cuttles live in the open sea, and they are not 
common on the shore rocks. 

In studying the Mollusca we shall first consider the 
Gasteropods, beginning with some old-fashioned forms, which 
are sometimes separated from the Gasteropods, because they 
are in many respects of simpler structure. These are the 
species of Chiton, animals very common on our coasts, and 
known as fossils from very early rocks. So 
abundant are the Chitons on the shore rocks, 
that one species at least can always be found 
.even at the most sluggish of neap tides. They 
live on and under stones, and are of small 
size, being usually not more than about half 
an inch in length, and often less. The shape 

FIG. er.-CMto ( see Fi S' 67 ) is a lon g oval > and the most 
marginatus, marked characteristic in surface view is the 

showing's presence of no less than eight overlapping 
eight shells, shell-plates, embedded in a tough roughened 
mantle, which projects at the margin of the 
plates. Remove the animals from the rocks with your 
ringers, and you will find that they immediately begin to 
curl up, bending the body at the junctions of the plates. 
Watch living specimens crawl over the muddy shale, and 
notice the slug-like movement, and the muddy track left on 
the rock. Induce your specimens to crawl up the side of a 
clear glass vessel, and study the under surface. In the 
centre lies the foot, a muscular creeping surface, as in 
limpet or snail. In front of it, and not clearly separated 
from it, is the head, without tentacles or eyes, but with a 
very distinct mouth-opening. By watching closely you may 
see a brown ribbon protruded from this opening, and used 
to scrape off the glass the small green Algse which soon 
grow in aquaria ; thus Chiton has a radula in its mouth just 
as the limpet has. At the sides of the foot are the gills, 
arranged in longitudinal series, and usually about sixteen in 
number. The posterior opening of the food canal is at the 
extreme end of the body, as far as possible from the mouth. 


We cannot here go into the minute details of the struc- 
ture of Chiton, but may briefly call attention to its more 
salient features. It is a true Mollusc; it has a mantle 
which secretes the dorsal shells, a ventral foot, it breathes 
by gills. It resembles the Gasteropods in the condition of 
the foot, and in possessing a radula or tooth-ribbon within 
the mouth. But it differs in many respects from the 
Gasteropods. Instead of having one shell it has eight; 
in place of the single gill of most Gasteropods it has eight 
pairs ; instead of being unsymmetrical, with the organs 
apparently twisted to the right, it is perfectly symmetrical 
with mouth at one end and anus at the other, like worm 
or Arthropod. In brief, it is a simple and primitive form. 
It should be especially noticed that it resembles worms and 
Arthropods in showing traces of segmentation. We have 
already noticed that in both these groups the body is made 
up of a repetition of similar parts is distinctly segmented. 
Now in the Mollusca such segmentation is typically absent, 
its absence being one great point of contrast with the 
Arthropods. The number of shells in Chiton, and their 
relation to the gills, point, however, to the existence of 
segmentation in this primitive form. This is a point of 
much interest to those who care about problems of origin. 

The species of Chiton are chiefly distinguished by the 
minute characters of the shells. The commonest form is 
Chiton marginatus, and is very variable in colour and size, 
but is distinguished by the finely granular surface of the 
valves. Each valve has a slight central keel prolonged 
posteriorly into a small beak, and is divided into three 
areas by two diverging lines. All the areas are similarly 
marked with fine dots, sometimes partially rubbed off in 
old specimens. The colour is usually greenish, marked 
and dotted with pale colour, but bright red varieties also 

Another common and much prettier species is 0. fascicu- 
laris, characterised by its comparatively small valves, and by 
groups of bristles placed on the margin of the mantle. 
There are eighteen of these groups, four being placed in 
front of the first valve and a pair in front of each succeed- 
ing valve. The individual valves should be examined with 
a good lens, when their brilliant colouring and beautiful 


markings are clearly seen. Each has a central ridge orna- 
mented by coarse longitudinal lines and ending in a beak, 
and two lateral areas ornamented by curious " tear-shaped " 
granules, whose pointed ends are directed towards the 
beak. The sculpture as a whole is interesting and very 

Another species, C. ruler, easily recognised but not very 
common, is of a bright, shining red colour, marked and 
variegated with white. The surface of the valves is per- 
fectly smooth and without trace of sculpture. 

By far the commonest species is C. marginatus, which is 
abundant everywhere on shore rocks. It is almost confined 
to the littoral zone, and is very variable. 

After the Chitons we come to the Gasteropods proper, in 
which the shell, when present, is always simple and often 
coiled. The classification is a matter of some difficulty, for 
those now in use depend upon anatomical details which are 
somewhat beyond our scope. We shall consider the true 
Gasteropods as divided into three orders: (1) the Zygo- 
branchia, (2) the Azygobranchia, (3) the Opisthobranchia. 
The first order includes the limpets, of which there are 
many kinds. Sometimes two gills are present, sometimes 
only one, as in Acmc&a, while in yet other cases, as in 
Patella, there is no gill at all. The name, which signifies 
" gills paired," is therefore a little deceptive. The shell is 
usually cap-shaped, and never more than very slightly 
coiled. In the general case there is little difficulty in 
recognising the common limpets. 

The Azygobranchia ("gills unpaired") include the great 
majority of the snail-like Gasteropods of the shore. The 
shell is usually large and coiled, and there is a single gill. 
The third order, the Opisthobranchia ("gills posterior"), 
includes forms which are often not easy to recognise as 
Molluscs at all. The shell is often absent, and is never well 
developed. When a gill is present it is placed behind the 
heart, instead of in front of it as in other Gasteropods ; but 
usually there is no true gill, its place being taken by out- 
growths of the mantle. Often brilliant in colour and quaint 
or beautiful in form, there is at least no fear of confusing 
the Opisthobranchs with other Gasteropods. They are 
very abundant on the shore, especially at certain seasons 


of the year; the commoner forms are called sea- slugs or sea- 

For clearness let us briefly summarise this classification of 
Gasteropods, or Molluscs in which the foot forms a ventral 
creeping sole. 


1. Zygobranchia, limpet-like forms, generally with 

simple, more or less conical shell. 

2. Azygobranchia, forms like whelk and periwinkle 

with coiled shells. 

3. Opisthobranchia, forms in which the shell is often 

absent and never well developed. 

The Chitonidae with eight shells and eight pairs of gills 
are often separated from the true Gasteropods. 

We shall take first the limpets as representatives of the 
Zygobranchia. On the East Coast, at least four of these are 
common between tide-marks. Commonest of all is Patella 
vulgata, the limpet of the fishermen, which is too familiar to 
need description. It is always abundant between tide-marks 
on rocky coasts, and is often found in little pits or depres- 
sions of the rock, into which the shell exactly fits. It has 
been shown by experiment with marked limpets that each 
limpet has its own particular habitation, to which it retreats 
as the water begins to ebb. When the rock on which the 
limpet has settled down is covered again with water, how- 
ever, the limpet sets out in search of the Algse which form 
its food. As it travels it forms a broad track, often very 
distinct where it has crossed sand or muddy rock. Experi- 
ments on the " homing instinct " of limpets are easily made, 
and can be carried out at neap tides on days when other 
shore work is largely stopped. The common limpet is in 
great demand for bait on most parts of the coast. It seems 
popular with most fishes, a somewhat curious fact since it is 
so purely littoral in habit. It is in many ways an interest- 
ing species, and the student should not fail to watch the 
way in which the peculiar tongue is used to mow down the 
small Algae on which it feeds. As it glides over the rocks 
the long tentacles are moved about in all directions, and 
show clearly the small eyes at their bases. The position of 
the eyes should be contrasted with that seen in the garden 


snail (Helix), where the eyes are borne at the end of the 
long tentacles. Most common marine Gasteropods have eyes 
placed in the position seen in Patella. 

The next limpet we shall consider is a much prettier form 
than Patella, and in its own area almost as common. To 
find it we must choose a spring tide, and tramp steadily 
outwards till we top the last reef, and come down to the 
sea-meadows where the giant Laminarice flourish. Choose 
a spot where you can look down on the floating fronds, and 
you will see that they are spotted with tiny shells of the 
same tint as the weed, but barred with radiating lines of 
shimmering blue. The colour is of the kind known as 
optical, and as the long fronds sway gently in the water, 
its living jewels glow blue or green according as the light 
touches them at one angle or another. When first seen 
under favourable conditions this is one of the sights which 
stay in the memory, for there is something in the exact 
harmony of colour between weed and shell which seems to 
give the blue colour an added glow. Beautiful as the 
limpets are, however, they are not quite harmless com- 
panions for the oar-weed, for you will find that they eat 
very considerable holes in its fronds, in spite of their small 
size as compared with them. Pull up a plant of Laminaria 
by the roots, and embedded in these, in company often with 
many other strange creatures, you will find another variety 
of the limpet. While the first variety is a thin, delicate, 
transparent shell, brown in colour with blue rays, the second 
is much stouter, paler in colour, and usually without trace of 
the blue rays. The first is the typical Helcion. pellucidum, 
the second Helcion pellucidum var. Iccvis. The first eats 
the fronds of the oar-weed, and so produces those torn and 
ragged fragments which are constantly thrown on the beach ; 
the second, by burrowing in the roots must weaken these, 
and so assist the waves in tearing up the great plants which 
appear on the shore after every storm. They usually bring 
with them many curious and beautiful creatures, so the 
naturalist has some reason to be grateful to the tiny limpet. 

The transparent limpet is closely related to Patella, and 
in the absence of a true gill differs from the next two 
limpets, Acmcea testudinalis and Acmcea virginea, which 
both possess a delicate white branchial plume. In habitat 


they offer the same contrast as Patella and Helcion, for 

while the tortoise-shell limpet is to be found not far below 

high-tide mark, Acmcea virginea is only to be found among 

the LaminarioB. We have, however, already (p. 24) seen 

that Acmcea testudinalis differs from the common limpet in 

being confined to the pools, and in never 

climbing high above the water level, as 

Patella vulgata does. It is a pretty little 

creature, easily recognised by the distinct 

pattern in brown on the shell, and the very 

dark brown " spatula " or mark in the inside 

of the shell. The mantle is bright green FIG. 68. Tortoise- 

and the eggs bright red, so the animal does (AcmLa l lestudt 

not lack bright pigments. The allied form, naiis). 

A. virginea, is of similar size and appearance, 

but has the shell ornamented with rays of pink instead of 

the brown network of the other species. The spatula is 

not brown, and the mantle has not the vivid green colour 

of the tortoise-shell limpet. It will be found attached to 

shells and stones in the Laminarian zone. On the South 

and West Coasts other limpets will be found in addition to 

these four. 

After the limpets we come to the Azygobranchs peri- 
winkles, whelks, dog-whelks, and similar forms, with strong 
spiral shells and active habits. To make sure of them 
collect on the shore a handful of common forms, such as 
the large whelks, very common in some places under muddy 
stones, a few periwinkles, some living tops ("silver Tommies"), 
or any other spirally coiled shells which catch your eye, and 
drop them into a basin of clean water. Note the different 
shapes of the shells, largely dependent upon the number 
and shape of the coils, and also the fact that while some of 
the shells have smooth rounded mouths, others, such as the 
whelks, have the mouth prolonged into a canal. Note, too, 
the general characters of a coiled shell; all have a centra] 
pillar or columella, a large body-whorl, a spire made of other 
smaller whorls, a mouth with outer and inner lip, and so on. 
Another point will be very obvious, namely, that not only 
can the animal retreat into its shell in a way which is 
impossible for a limpet, but that when it does retreat it 
" shuts the door " behind it, by means of a firm plate, or 


operculum (o in Fig. 70), so placed as to block the mouth of 
the shell when once the animal has withdrawn into it. If 
the chief function of the shell be for protection, then the 
shell of the Azygobranchs is more efficient than the shell of 
the Zygobranchs. 

While you have been making these observations, some of 
your specimens will have recovered from their alarm, and 
have begun to crawl about the basin. In such expanded 
specimens notice as before the creeping foot (/ in Fig. 70), 
not unlike that of the snail, and also the relation of the 
operculum to it. A comparison of forms with notched and 
unnotched shell will show further that in the former a long 
tube or siphon (see Fig. 70, s) can be protruded along the 
canal or notch. This siphon is a specialised portion of the 
mantle, and conveys water to the mantle-chamber in which 
lies the gill. You will remember that in the tortoise-shell 
limpet the gill itself is protruded as the animal walks ; but 
gills are delicate, easily injured structures, full of blood, 
and not to be exposed without some risk, therefore we 
find that with the specialisation which gives the Azygo- 
branchs their more complex shells, there is usually more 
efficient protection for the gill, which is now usually hidden 
permanently within the mantle-chamber. Lest, however, 
in this position the gill should not be sufficiently exposed to 
the purifying action of the water, there is in many cases a 
long siphon which conveys a current of water to the mantle- 
chamber. We have already noticed a similar condition of 
affairs in the Crustacea, where in the higher forms the 
position of the gills in a gill -chamber necessitates very 
elaborate arrangements for renewing the water. Curiously 
enough it is found that almost all the siphonate Azygo- 
branchs are carnivorous, while those without siphons are 
vegetarian. The former are more specialised than the latter. 

Notice, also, that the Azygobranchs have a much better 
developed head region than the limpet. It is often prolonged 
into a proboscis, which may, as in the whelk, be capable of 
being protruded and retracted. The tentacles are often very 
long, and in some cases, as in the tops, there are numerous 
tactile processes in addition to the tentacles proper. 

While the limpets lay their eggs singly in the water, the 
Azygobranchs lay them in clusters or capsules which arc 


often curious and interesting in appearance, and in several 
cases are among the commonest of the objects found on the 

Among the Azygobranchs we shall begin with the familiar 
"silver Tommies" of our youth, the "tops" of south- 
country children, and the Trochi of scientists. All children 
recognise at least two varieties, the common "silver 
Tommies," valuable only in very early youth, and the large 
pink ones, which, with the finer scallops, constitute the 
gems of all early collections. The common form is Trochus 
cinerarius, and can always be found in the living condition 
on the rocks; the large is T. zizypliinus, and is an inhabitant 
of deeper water, sometimes tossed on shore after storms. 
There are, however, especially in the South, very many other 
species, some of which live in deep water, and others on 
the tidal rocks. Choose the species which is most abundant 
in the locality at your disposal it will probably be Trochus 
cinerarius and study it in the 
living condition. Notice the small 
conical shell, with its rounded, un- 
notched aperture the animal has 
no siphon, and is vegetarian. As it 
protrudes itself from the shell, notice 
the operculum borne on the foot, the 
foot itself, narrow in proportion to 
its length, the large head prolonged 
into a non-retractile snout, and bear- 
ing two long tentacles, and two eyes 
placed on short stalks, which spring 

from the base of the tentacles. Between the tentacles are 
two distinct " head-lobes," while to their outer sides lie two 
greatly developed " side-lobes," with long, delicate processes, 
or cirri (see Fig. 69). The cirri move about as the animal 
progresses, and add considerably to its appearance. The 
operculum is peculiar in being spirally coiled, as it is in all 
the Trochi. 

As to the special characters of the shells of the different 
species, in T. cinerarius the whorls are somewhat flat, and 
six in number, the base of the shell shows a narrow hole 
called .the umbilicus, the shell is marked by coarse, spiral 
lines, and is of a dull ash colour, marked by oblique lines 


of darker tint, which run in the opposite direction to the 
lines of growth. Shells found on the beach often have the 
outer coat rubbed off, and are then "silvery," that is, they 
show the mother-of-pearl lining. 

The large Trochus zizyphinus (see Fig. 69) is on the 
east an inhabitant of deep water; on the west it occurs 
between tide-marks, and the shell is common on most 
shores. The shell is conical in shape, and may reach a 
height of over an inch, the base is without a perforation, 
there are eight or ten whorls, and the shell is usually 
spotted with bright rose colour. In the general case the 
species is readily recognised. 

There are very many other species of Trochus found in 
Britain, some in deep water, and some found in the tidal 
pools in the South and West. 

The next set of forms we shall consider are the peri- 
winkles, an interesting and puzzling group. As the name 
of the genus Littorina indicates, they are purely littoral 
forms, living almost exclusively between tide-marks, and 
showing much tolerance of fresh water and of dryness. On 
the one hand they are related to the genus Lacuna, whose 
members inhabit the Laminarian zone and deeper water, 
and on the other they are connected with Paludina, a genus 
of fresh -water forms, and they occupy every variety of 
habitat between those of these genera. High up on the 
cliffs, out of reach of all but the spray, on the stones of 
the streams which run down the beach, on the tidal rocks, 
on the broad blades of Laminaria, there are few localities 
on the shore in which the ubiquitous periwinkles do not 
occur. It is true that in most cases the different localities 
are characterised by one dominant form, but in not a few 
cases the species themselves have a wide range, and I have 
picked four so-called species off one stone. You probably 
do not need to be told that this is very exceptional, and for 
a very obvious reason. It is an axiom of the modern theory 
of evolution that those divergences of structure which ulti- 
mately result in the formation of new species have been 
produced by divergences in the environment. Take as an 
example the two species of porcelain -crab already con- 
sidered (p. 179). The minute porcelain -crab is adapted to 
one environment, the hairy porcelain -crab to another, and 


their differences are directly associated with the differences 
in their surroundings. The latter, by virtue of its hairy 
coat, can live among mud, which the former cannot. It, 
on the other hand, from its superior agility, can probably 
escape enemies which the other could not, and is therefore 
enabled to live in more exposed places. If hybrids between 
the two were to occur they would probably be well adapted 
for the habitat of neither, and so would tend to be elimi- 
nated. In other words, marked and permanent differences 
of environment tend to produce marked and permanent 
differences in species. 

If we return to the periwinkles we find that there is no 
such marked difference in the environment in this case. 
They are tolerably active animals, and therefore, though 
each species may theoretically have its own zone, its mem- 
bers seem to wander freely into the zones of other species. 
This must have two consequences. In the first place, 
divergence will be probably checked by constant inter- 
breeding; secondly, if the adults wander freely, their 
adaptation to any particular locality cannot be very exact, 
and there is no reason to believe that hybrids will be more 
likely to be eliminated than pure forms. That is, the 
species should not be well defined. Now this is what 
actually occurs; there are a great number of periwinkles, 
and in many cases it is almost impossible to distinguish 
between species and varieties. There can, I think, be no 
doubt that this is due to the continuity of the environment. 
It naturally, however, makes the identification of species 
very difficult, and the distinction of species a fruitful source 
of controversy. A modern will no doubt say their distinc- 
tion is a matter of no importance; but if the attempt 
makes clear the meaning of variation, it is not without its 

Let us first answer the question, What is a periwinkle? 
All the periwinkles have solid top-shaped shells, with a 
short spire and an entire mouth. The surface of the shell 
is sometimes smooth, sometimes spirally grooved. The 
mouth is nearly circular, and has a sharp-edged outer lip, 
while the other or columellar lip is expanded. The oper- 
culum is pear-shaped, horny, spirally coiled, with its centre, 
or nucleus, laterally placed. In the living animal the head 


is seen to bear two tentacles, which have two almost sessile 
eyes at their bases. There are no lobes nor cirri such as 
occur in Trochus. The foot is rounded at both ends, and 
has a very distinct central groove. Make out these points 
on a living common periwinkle, and then make a special 
journey to the rocks to collect the different forms in the 
living condition. Begin at high-tide mark and collect speci- 
mens down to low-tide mark. Then, either indoors or at 
the rocks, sort your specimens carefully. Pick out first the 
common periwinkle (Littorina littorea), which is known by 
sight to most people, and is almost always easy to recognise. 
The shell is usually black, sometimes brown or red ; in the 
young the surface is ridged, but the adult shell is often 
nearly smooth. Having put aside all the specimens which 
are obviously the edible kind, take out from the remainder 
those with distinctly flattened spire, in which the coiled 
part of the shell seems to be sunk into the last whorl. 
This is L. obtusata. The shell has a peculiarly smooth 
surface, and is very variable in colour, being usually shades 
of yellow and brown. It lives chiefly among bladder wrack 
(Fucus). Among the remaining specimens you will find a 
number of yellowish colour, often banded, which, except 
for their colour, present much general resemblance to the 
common periwinkle. From it they differ especially in the 
greater roundness of the whorls, and in the breadth of the 
outer lip of the mouth, at the point where it joins the 
columella, or pillar, which forms the central axis of the shell. 
The result of this broadening of the outer lip is to give the 
aperture the appearance of being partially filled up. This 
form is L. rttdis, a species which lives near high-tide mark, 
and is very variable, giving rise to several more or less 
distinct varieties. The most distinct of these is the form 
called L. patula, which has an ear-shaped shell with a 
somewhat oblique spire. There are other species or varieties, 
such as L. neritoides, a small form living above high-water 
mark; but if those mentioned above are distinguished the 
observer will do well. 

The special characters of the forms named may be briefly 
described. The common periwinkle, Littorina littorea, is 
denned by the combination of the following special charac- 
ters : the surface of the shell, especially in the young stage, 


is marked by striae, the whorls are more or less flattened, 
the outer lip of the aperture joins the last whorl at an 
acute angle, and is more arched below than above. On the 
last point special stress should be laid, as it is very character- 
istic. The colour of the shell has been already described'; 
as to the colour of the living creature, the fact that the 
horns and tentacles are spotted and ringed with black is 
especially noteworthy. 

It is much easier to distinguish between actual specimens 
of L. littorea and the next species, L. rudis, than it is to say 
wherein the difference actually consists. In the latter the 
whorls are distinctly rounded, the outer lip joins the last 
whorl at a right angle, and is more arched above than 
below. This, which is an important difference from the 
common periwinkle, may seem a very trivial matter, but it 
has, in reality, considerable bearing on the life-history. The 
common or edible periwinkle lays eggs on Fucus in little 
jelly-like patches, a habit which is no doubt the primitive 
one for the species. But such a habit is obviously im- 
possible for forms like L. rudis and its varieties, for they 
inhabit localities often not covered by every tide, and un- 
suited to the growth of the tangles. It therefore retains its 
eggs within the body until the .young develop, and they are 
subsequently born already furnished with shells. There 
can be little doubt, I think, that the shape of the shell- 
mouth bears a direct relation to this viviparous habit it 
allows room for the young to develop, and makes birth easy. 
Practically, the viviparous habit is of some importance, 
because it renders this species unfit for food, owing to the 
grittiness imparted by the presence of the young during 
several months of the year. The species never reaches the 
size of the preceding. 

The form called L. patula is merely a variety of L. rudis, 
but lives even further up on the shore. It is usually smaller, 
has a thinner shell and a more stunted appearance, the 
whorls, especially the last, are more expanded, and the 
aperture of the shell is wide. As in L. rudis, the tentacles 
of the living animal are usually marked with longitudinal 
stripes, not with rings or spots, as in L. littorea. 

Typical examples of L. obtusata are so easy to recognise 
that it seems unnecessary to describe their characters 


further than to re-emphasise the peculiar flatness of the 

The four types given here have been chosen because I 
have found them to be the most abundant on the shores of 
the Firth of Forth, but the periwinkles of any area form a 
most interesting study. 

Related to the periwinkles are two genera of minute 
shells, which we can only mention without description. 
The first of these is the genus Rissoa, which includes a 
great number of British species, inhabiting very various 
depths of water. To obtain examples pluck a good handful 
of any of the finer seaweeds, and drop into a dish of sea- 
water. Presently there will crowd to the surface numerous 
minute forms with spirally coiled shells often beautifully 
sculptured. They are active little creatures, crawling over 
the seaweed, or taking advantage of surface tension to creep 
along the surface of the water, shell downwards. The 
other genus is Skenea, including especially Skenea planorbis, 
a common shore form with a circular depressed shell. It is 
very minute, being just visible to the naked eye. 

On many parts of the coast " tower-shells " (Turritella) 
are found very commonly thrown on the beach. There is 
only one British species (T. communis), and it is an 
inhabitant of deep water, so that the living animal is not 
likely to be found. The shell is elongated and tapering, it 
has sometimes as many as nineteen whorls, of which the 
first ten bear three distinct ridges. The aperture is entire 
and rounded. The shell is usually of a brownish colour, 
and may be over two inches in length. 

Though Molluscs which only occur in the dead state are, 
strictly speaking, somewhat outside our scope, we must 
mention the curious " pelican's foot," Aporrhais pes-pelecani, 
which is not infrequent on the shore. The shell is turreted, 
very strong, with numerous ornamented and ribbed whorls. 
The mouth of the shell is furnished with a short canal, 
and in the adult its outer edge is expanded into a large 
lobed plate. The shell is interesting on several accounts, 
especially because it is in some respects transitional between 
the Azygobranchs, with round entire aperture like Trochus, 
and those with canaliculate, or notched aperture like 
Bvacinum. The living animal is beautifully flecked with 


scarlet, and may occasionally be found flung ashore after 

Before passing to the siphonate Azygobranchs, we must 
mention one other form not uncommon in some places 
between tide-marks which is very different in appearance 
from its allies. This is Lamellaria perspicua, especially 
interesting because the shell is very thin, and is completely 
covered by the mantle. This reduction of the shell occurs 
in many different sets of Gasteropods, but is rare in the 
littoral Azygobranchs. In Lamellaria the body is very 
convex, without external trace of shell, is usually yellowish, 
but may be white or purplish. The head bears two tentacles, 
with small eyes at their bases. The animal is very active, 
and may reach a length of two inches, but between tide- 
marks specimens are usually of very much smaller size. It 
is possible, by very slight dissection, to find the concealed 
shell which lies in the middle of the back, .and is of a 
delicate white colour, with a mere trace of a spire. The 
living animal is apt to puzzle the beginner very much, for it 
has few characters which can be very definitely laid hold of, 
and specimens between tide-marks are not infrequently of 
very small size. On the dorsal surface notice the rounded 
mantle, often highly spotted and marked, and with a very 
characteristic notch anteriorly over the head, which serves 
as a kind of siphon to admit water to the small chamber in 
which the gill lies. When the animal crawls it trails a 
translucent foot behind it, while the long, slender tentacles 
project in front. If it be turned over, the broad, creeping 
surface of the foot will become very obvious, and also the 
large, black eyes at the base of the tentacles. The animals 
are to be found under stones between tide-marks, and on 
account of the activity of their movements are very charm- 
ing occupants of an aquarium. 

Of the carnivorous siphonate Azygobranchs, the common 
Purpura lapillus is perhaps the most abundant 011 the shore. 
Like many of its allies it yields a purple dye similar to 
that which furnished the ancients with their famous Tyrian 
purple. In some places it is called the dog-periwinkle, and 
is one of the most variable of shore animals, and one of 
the most abundant. It is purely an inhabitant of the 
littoral zone, and lives upon other Molluscs, chiefly Bivalves, 


which it attacks by first drilling a round hole in the shell, 
and then sucking up the soft contents by means of its pro- 
trusible proboscis. At low tide the dog-periwinkles remain 
motionless attached to the dry rocks, but they have a curious 
habit of suddenly relaxing their hold and dropping into 
the pools beneath. Beneath overhanging rocks their egg 
capsules may be found at all seasons, sometimes empty 
and sometimes full, and not infrequently stained with the 
creature's purple dye. 

The shell is very strong, usually white or pale yellow, 
with a very large body-whorl and a distinct but short canal, 
and in the adult reaches a length of over an inch. The 
surface is usually nearly smooth, but in one variety the 
lines of increase rise up to form "fringe-like imbricating 
lamellae," and there are in addition spiral ridges placed very 
close together. The colour is very variable, the shell being 
sometimes banded with dark brown and sometimes entirely 
dark brown ; the shape is also variable. 

The living animal is pale in colour, usually white. Behind 
the head lies the gland which secretes the colourless fluid 
from which the purple dye is obtained by exposure to the 
air. The egg capsules are little oblong, shortly-stalked cups, 
and are placed in clusters on stones and shells. 

The next two species belong to the genus Nassa, and are 
usually more abundant as shells on the shore than in the 
living condition. The shells are prettily marked, and in 
the young state are often collected by children in quantities 
to make necklaces or ornaments. Both species are some- 
times found living near low-tide mark. 

The larger species, Nassa reticulata, has a thick shell of 
pale brown colour, which may reach a length of one and 
a half inches. It is covered by numerous convex ribs, 
which are crossed by spiral grooves, producing a netted 
appearance. The aperture is prolonged into a short and 
broad canal. The animal is yellow, speckled with black, 
and has the foot prolonged into two filaments, usually 
carried upright when the creature walks. 

The other species, N. incrassata, is much smaller, has the 
whorls of the shell rounded, and a dark spot placed at the 
origin of the canal. The aperture is largely filled up by a 
projection, or varix. 


The next form is a very interesting one it is the common 
whelk, or "buckie" of Scotch children. Between tide- 
marks it is usually small, but in deeper water grows to a 
length of six inches, and in many places is much valued 
both as food and bait. It is very widely distributed and 
common, and, like so many other common shore Gastero- 
pods, is very variable, tending especially to run into local 
varieties. It is extraordinarily abundant between tide-marks 
in the Firth of Forth, where it lives chiefly in mud and 
sand, and is often beautifully coloured. The egg capsules 
are very common objects in autumn and spring, both on the 
shore rocks and cast up among the refuse on the sand. 
They are interesting objects and well worth study. 
Each capsule has a tough wrinkled coat and is of irregular 
shape, and the capsules are aggregated together in masses 
varying in size from a small cluster like half a lemon to a 
mass as large as a child's head. The spawning season is in 
autumn, though, as in many Molluscs, it seems to be of long 
duration. Each capsule when laid contains 500-600 eggs 
inclosed within a space of a quarter of an inch to half an 
inch in diameter, so that some estimate may be formed of 
the enormous number of eggs produced by the parent. 
Relatively very few of these eggs, however, develop. For 
some reason not yet adequately explained, some five or six 
in each capsule get the start, and begin to develop rapidly. 
As they do so they devour their less successful brethren, 
and on opening the capsules one finds the infant monsters 
with their transparent bodies distended by some seventy to 
eighty undeveloped eggs. By the help of this food they are 
enabled to remain within the egg-case until the shell is fully 
formed, when, in spring, they finally leave it, and begin life 
on their own account. This sacrifice of many eggs to the 
few which develop is common among shore Gasteropods, but 
it can be observed perhaps most readily in the common 

Whelks are probably more or less familiar to most people, 
so it is not necessary to describe them in very great detail 
(see Fig. 70). The living animal is both interesting and 
beautiful, and an attempt should be made to keep a few 
specimens in confinement. To do this with success it is 
necessary that they should be supplied with a considerable 



bulk of water. In such living specimens notice the strong 
operculum (o) with which the shell can be entirely closed, 
the large creeping foot (/) beautifully mottled and speckled 

with black, the long 
siphon (s) which is 
protruded along the 
canal of the shell 
and waves freely in 
the air as the animal 
walks, the broad 
head (h) with the 
pointed flattened 
tentacles bearing 
the distinct eyes, 
and the long pro- 

Fio. 70. Common whelk (Buccinum undatum), show- boscis which can 
ing the animal as it appears when crawling. For *, nro trndpd from 
explanation of letters see text. 3 protru 

the mouth. The 

shell varies considerably in colour, but is usually more or 
less brownish; it is spirally grooved and striated, and 
usually marked with oblique transverse undulations which 
do not traverse the whole of the body-whorl. It is very 
thick and strong, especially in forms from deep water. It 
is not usual to find the whelk abundant between tide- 
marks except in the North, but, as already noticed, it is 
very common on the coasts of the Forth. 

Allied to Buccinum is the genus Fusus, whose members 
are called spindle-shells, or red whelks, or buckies. The 
two commonest species in the North are F. antiquus and 
F. islandicvs. Both are inhabitants of deep water, but are 
sometimes thrown up in the living state by storms. The 
shells are common on the shore at all seasons, and are not 
infrequently found in rock pools occupied by hermit-crabs. 
A full-grown hermit requires for his accommodation an 
adult shell of Buccinum or Fusus antiquus, and when the 
latter is chosen the result is singularly beautiful. The shell 
is usually pure white, the colour deepening into yellow 
within the large aperture. It may reach a length of over 
six inches and is always peculiarly graceful in shape. The 
shell of Buccinum, on the other hand, is only beautiful 
when small, the large specimens tending to become thick 


and clumsy. The other species of Fusus, F. islandicus, is 
much smaller and more distinctly spindle-shaped; the two 
species may be recognised and distinguished by the following 
characters. In the larger species the surface of the shell is 
covered by numerous strong striae placed very close together. 
The mouth is very large, being longer than the spire, and 
about twice as long as it is broad. The result is to produce 
a shell which is very wide at its lower part and only tapers 
very gradually above. In Fusus islandicus the surface is 
covered by relatively few strise, separated from each other 
by an interval broader than they are themselves. The 
mouth is not so long as the spire, and the breadth is only 
about a third of the length. In consequence the body- 
whorl is narrow, and tapers suddenly to a somewhat sharp 

The only other of these Gasteropods we shall mention is 
that curious little one known as the " blackamoor's tooth," 
or cowry, which is so common on the beach, and is so often 
collected in hundreds by enthusiasts who spend the greater 
part of their summer holiday poring over the beds of 
gravel in which the little shells are found. I have often 
wondered whether the results in the shape of long necklaces 
of perforated shells are worth the labour and the backaches 
of the gathering. The living animals, however, are exceed- 
ingly interesting, and may sometimes be found on the rocks 
near low-tide mark. When fully expanded two bright 
orange folds envelop the shell so as to almost conceal it. 
The tentacles are very long, and, like the rest of the head, 
the foot and the siphon, are of a pale yellow colour. When 
very young the shell is coiled as in most Azygobranchs, but 
as it grows the spire is concealed by the growth of the 
body-whorl, and the inflection of the lip produces the long 
narrow aperture so characteristic of the cowries, to which 
family the present form the Cyprea europcea of systematists 
belongs. The living animal is a most gorgeous little 
creature, the prevalent orange tint being often set off by 
bands and markings of other colours, or replaced by a 
pinkish colour. The shell is quite white, as is often the 
case with concealed shells. 




CHITONID.E, one genus, Chiton 

Surface of shells finely granular 
Surface quite smooth. Colour red 
Mantle with tufts of bristles . 

8 shells, 8 pairs of gills. 

C. margiiiatus. 

G. ruber. 

C. fascicularis. 


(1) GASTEROPODA ZYGOBRANCHIA (shells cap-shaped). 

{Shell with strong \ p a t e 77 a 
ridges . . . / 
Sh a e nd Sate 8 ? 100 * 1 ! } ^kion pellucidum. 
' Shell with tortoise- ^ 

shell pattern in V Acmcea testudinalis. 


One gill present 

(2) GASTEROPODA AZYGOBRANCHIA (shells spirally coiled). 
(a) Forms without a siphon. 

' T. cinerarius, 
shell with 
hole at 

Shells more or 
less top-shaped 

Base flat, shell \ 
pearly inside, f 
whorls nu- I Trochus 
merous. Ani- I 
mal with cirri. J 

Shell thick, not ^ 
pearly,whorls r Littorina 
few. No cirri. ' 


six whorls. 

T. zizyphinus, 
no hole, eight 
to ten whorls. 

L. littorea, shell 
red or black, 
surface ridged. 

L. oblusata, sur- 
face smooth, 
spire flattened. 

L. rudis, whorls 
round, lip 

Shells very long, J Whorls with \ 
with many-! tubercles, 
whorls . 

VU*/w4vJlvOj I 

outer lip ex- r Aporrhais pes-pclecani. 
panded into I 

Shell very thin, -v 
concealed, I 
mantle with j 
anterior notchl 


Lamellaria perspicua. 



(6) Siphonate forms. 

Spire sharp- \ 
pointed, canal r 
narrow . . ' 
Spire short, \ 
Shell oval, spir- canal short j 
ally sculp- I and recurved, I 
tured, canal \ columellaj 
short . . with fold at I 
base . . J 
Spire blunt, -\ 
canal open j- 
and deep . J 
Shell spindle- ] f 

shaped, with I 
long straight ( FuSUS ' '] 
canal . / I 

Shell with con- \ 

r p re SP 4 ^~^" 

Purpura lapillus, shell white or 

N. reticulata, 
shell large. 

N. incrassata, 
shell small, 
aperture much 


Buccinum undatum 

shell un- 

F. antiquus, strise numerous, body- 
whorl wide. 

F. islandicus, strise few, body- 
whorl narrow. 

For (3) GASTERoroDA OPISTHOBRANCHIA, see next chapter. 


From the great multitude of shell-bearing Gasteropods we have 
been able to pick out relatively so few that not much can be profit- 
ably said as regards the distribution generally. Most of the forms 
mentioned occur all round the coast. The whelks lusus islandicus 
and Buccinum undatum may be mentioned as forms commoner in 
the North than in the South, while the cowry (Cyprea) is an example 
of one commoner on the South and West, at least between tide- 
marks, than on the East Coast. We have already indicated that 
although the pretty tortoise-shell limpet is absent from the South 
and West, its absence is atoned for by many other curious and 
interesting forms. A similar replacement of species occurs among 
other genera. Thus at Lynmouth, on the north coast of Devon, the 
common grey top ( T. cinerarius) appeared to be absent, but the pools 
were filled with two other species a small one prettily marked with 
brown (T. umbilicatus), and a larger dark-coloured one (T. lineatus). 
But, allowing for such cases, it may be said generally that the 
Gasteropods which are hardy enough to live between tide-marks are 
also hardy enough to live all around our coasts. 



General characters of Opisthobranchs The sea-hare The sea-lemons, 
or Dorids Five common species The spawn and breeding habits 
Development Goniodoris, its structure and habits Some other 
sea-slugs General characters of the colouring Their inedibility 
and its causes The Eolids Three common species General notes 

WE now come to a singularly interesting and beautiful 
group of Gasteropods, mostly without shells, and often 
of very singular shape. They constitute the group of the 
Opisthobranchs, and, as already seen, are characterised by 
the fact that the heart is in front of the gill when this 
is present, instead of being behind it, as in the Gasteropods 
just considered. The greater number of these shell-less Gas- 
teropods are often called sea-slugs, or Nudibranchs ("gills 
exposed"), and certain sea-slugs are abundant on every 
shore. Most of them, especially the smaller kinds, live 
well in confinement, and should be studied in the living 
condition. They do not preserve well, both colour and 
shape being usually lost even under favourable conditions, 
and they are rarely to be found in museums ; so that unless 
you draw and describe your specimens as you find them, 
there is little chance that you will be able to name them 
afterwards. Again, many of them seem to be more or less 
migratory in their habits, and are not found between tide- 
marks except at the breeding season. As this usually falls 
in the colder months, you can hardly hope to find such 
species if your visits to the shore are confined to the 
summer. In March, for example, I have seen the shore 
rocks whitened by the spawn of forms which in summer 
are rare, but at this time occurred in clusters of five or six 



at every patch of spawn. One other point, the rocks at 
your disposal may abound with some of the smaller and 
more delicate forms, and yet you may be unable to find 
a single specimen. It must be remembered that out of 
water many of the sea-slugs collapse into a shapeless mass, 
while in the water they may so closely resemble the coral- 
lines or zoophytes among which they live as only to be 
distinguished with great difficulty. I do not know any 
more laborious task in shore hunting than crouching beside 
densely fringed pools and searching every weed for the tiny 
sea-slugs. I do not deny that the result is worth the 
trouble when some delicately tinted beauty rewards the 
search, but the trouble is not slight. However, storms are 
often kind to the ardent collector, and will toss up frag- 
ments of weed covered with zoophytes, among which many 
a prize may be found. Such fragments are always worth 
careful study, if found in the fresh condition. 

The first Opisthobranch we shall mention is the sea-hare 
(Aplysia hybrida, see Fig. 71), an animal unfortunately rare 
on the North-east Coast. I have found it between tide- 
marks, but its habitat is among beds of weed in the 
Laminarian zone, and especially among the blades of 
Zostera that strange marine flowering plant which grows 
at many parts of the coast, and is the favourite refuge of 
many curious animals. The sea-hare is an animal of 
singularly curious shape, with a characteristic smell, and a 
habit of pouring out a purple dye when alarmed. Round 
the animal and the dye many curious superstitions have 
clustered, especially in the Mediterranean, where the sea- 
hares grow to a large size, and have been known from 
ancient times. Those who are accustomed to argue that the 
wide distribution of a belief is a proof of its validity, will 
find some difficulty in fitting the sea-hare into their 
philosophy. The belief in its poisonous qualities is wide- 
spread, both among the ancients and among modern 
fishermen. Just as the gathering of poppies, or "thunder- 
cups," is likely to be followed by an avenging thunderstorm, 
so the foolish naturalist who wantonly handles the sea-hare 
will be smitten by fell disease. As far as my own experience 
goes, I may say that I think the one consequence is as likely 
to follow as the other, for the sea-hare is a perfectly harmless 


little creature, chiefly remarkable for its strange contortions 
and quaint shape. 

So variable is the shape that the animal is not easy to 
describe. There is also considerable variation in colour; 
when young the whole animal is violet or purplish, while in 
the adult state it is greenish grey, speckled and mottled 
with brown and white. The shell is not visible externally, 
and the body is dome-shaped, the slender head projecting 
markedly in front. There are two pairs of tentacles, of 
which the upper (t) are shaped like hares' ears, and bear 
the small eyes at their bases. At the sides of the body two 
large flaps, or epipodia (ep in Fig. 71), rise straight up, and 
almost meet in the middle line of the back. If you fold 
back the epipodium of the right side you will see behind it 

the single gill, and 
the curious grape- 
t shaped gland 
which secretes the 
purple fluid. Be- 
tween the epipodia 
in the mid-dorsal 
line lies the thin, 
papery shell, al- 
most entirely 
covered by the 

After Gosse. mant l e . The foot, 

as usual, forms a creeping surface, but both it and the 
epipodia are very contractile, and in life are constantly 
changing shape. When the animal is actively crawling, 
the foot projects considerably behind the body. Such an 
expanded specimen may measure from two to four inches 
from tip to tip. Between the epipodia on the dorsal surface 
there projects a siphon-like process of the mantle, which 
leads from the anus to the exterior. On dissection it is 
easy to find the heart lying in front of the gill, the curious 
horny jaws in the mouth, and the gizzard armed with horny 

The next genus we shall consider is the very large one 
of Doris, including the true sea-slugs, or sea-lemons. By 
recent authors this genus has been broken up into a large 
number of small genera, but as we shall only consider some 


half-dozen species, it is not necessary for us to name these 
new genera. 

The first species is very large, and is common in most 
places far out on the rocks. If at a low spring tide you go 
far out on the rocks and look carefully down the narrow 
clefts, you will probably see large weird creatures, yellowish 
in colour, soft to the touch, and shapeless in appearance. 
They often reach a length of over three inches, and are 
broad and massive. If you can successfully extricate them 
from the rock crevices, place your specimens in water and 
watch them unfold. There is no trace of shell, external or 
internal, and the branchial plume of Aplysia has also dis- 
appeared. The body is elliptical and depressed, and the 
head is not separated from it ; the mantle-fold of the Azygo- 
branchs is also absent. The dorsal surface is covered by 
what systematists call the cloak, or mantle, which is really 
equivalent to the epipodia of Aplysia. It is closely covered 
with round tubercles, and is strengthened by spicules. 
Through two little holes in it the short conical tentacles 
are protruded anteriorly. At the other end, also on the 
dorsal surface, is the median anus, which is surrounded by 
a circle of feathery "gills," not homologous with the gill 
of Aplysia. They are nine in number, are large and tri- 
pinnately cut, or fern-like, and can be completely withdrawn 
into the body. The foot forms a bright yellow creeping 
surface, and is as broad as the body. The upper surface 
in life is often bright in colour, with patches of blue-green 
on a yellowish ground. This is Doris tuberculata, the 
largest of our British Dorids. Like other species it lays 
white ribbons of spawn on the rocks, but the process 
is more easily observed in some of the more abundant 
species. I have not found it easy to keep in confinement, 
but there is usually no difficulty in obtaining specimens for 
examination, especially in the earlier part of the year. 

The next species, Doris johnstoni (see- Fig. 72), is rarer, 
but occurs occasionally between tide-marks. It is not very 
much smaller, for it may reach a length of two inches, but 
is readily distinguished by the different shape and the more 
numerous gills. The body is convex in the centre and 
markedly depressed at the sides; the dorsal surface is 
covered with very minute tubercles, and is blotched with 


brown on a ground colour of yellow or white. The dorsal 
tentacles are short and broad, and there are also a pair of 
slender oral tentacles at the sides of the mouth. There are 
fifteen tripinnate gills. 

The next species is much more beautiful and much 
smaller. It is called Doris repanda, is usually about an 
inch long, and is of a dead-white colour, with a row of 
yellowish white spots down each side. The back is covered 
with indistinct rounded tubercles, and there are only five 
small gills. The oral tentacles are broad and flat and the 
dorsal ones long, Like most of the smaller species, this 
one can take advantage of the surface tension to creep along 
the surface of the water back downwards, and is then a 

FIG. 72. Doris johnstoni. Note the gill-plumes and the dorsal 
tentacles. After Alder and Hancock. 

beautiful little object. The actively moving tentacles, the 
delicate branched gills, and the translucent whiteness of the 
tissues, make it a delightful occupant of an aquarium, but, 
like most of the Dorids, it requires some care in confinement, 
being apparently very sensitive to impurities in the water. 
It is not uncommon under stones on the shore. 

Another species is Doris bilamellata, which occurs in the 
Firth of Forth in February and March in countless numbers. 
It is no exaggeration to say that in these months the rocks 
are simply whitened by these little creatures and their 
spawn. They are not particularly pretty, and show no 
brightness of tint as so many inedible or noxious insects do, 
but seem to enjoy immunity from persecution to a very 
marked extent. I have not found any shore animal which 
will eat them, and even the sea-gulls seem to leave them 


alone. Possibly the slime with which they are covered has 
something to do with their immunity. They have a curious 
habit of congregating, not in pairs, but in clusters of three 
to seven or so, and laying their eggs in continuous masses. 
The eggs are embedded in a tenacious jelly analogous to that 
which surrounds the eggs of frogs. By means of this jelly 
not only are the eggs attached together to form a ribbon 
about half an inch broad, but also one side of the ribbon is 
sufficiently sticky to adhere to the rock surface, and as the 
ribbons are laid in spirals, they stand up from the rocks like 
ladies' frills. Such ribbons are found on the rocks during 
almost all the colder months of the year, but are most 
abundant in February and March. 

You should not fail to obtain a small stone bearing spawn, 
and carry it home with you to place in an aquarium. By 
means of a lens you can make an attempt to estimate the 
number of eggs in an inch of the ribbon, and so get an idea 
of the countless numbers of eggs laid by each individual. A 
few pages back we discussed the egg-laying habits of the 
whelk, and noticed the wholesale sacrifice of eggs which 
takes place within the egg-capsule. Nothing of the kind 
occurs here. If you are successful with your spawn you 
will find that from each egg a tiny colourless larva hatches 
out, so that the water of your aquarium becomes cloudy 
with the myriads of swimming specks. These larvae are 
very diS'erent from the adults, and for a time are furnished 
with the shell which the adult has lost, and with a power of 
swimming of which the adult shows no trace. Stir the 
water in your aquarium gently, and notice how at every 
movement hundreds of larva? are thrown up on the sides of 
the glass, there to speedily perish. Think of the wash of 
the sea over the shore rocks, of the dangers from enemies, 
and you will realise that, ruthless as the methods of the 
young whelks seem, they are probably justified in their 
results. It is probably better that many of the eggs should 
be sacrificed to feed the few, if these few are thereby 
enabled to remain within the egg-case until the early stages 
of their development have been passed through, rather than 
that all the eggs should be hatched in a condition when 
their power of resistance to unfavourable conditions is very 
slight. On the other hand, it should be noticed that the 


existence of a free-swimming stage in Doris must facilitate 
distribution. It is possible that the young may travel 
distances impossible to the sluggish adults. 

To return to the special characters of Doris bilamellata. 
The body is about an inch in length and is greyish speckled 
with brown; the back is covered with numerous large 
unequal tubercles, and there are numerous simply pinnate 

A prettier species is D. pilosa, which is also very com- 
mon in the Firth of Forth, and is about the same size 
as the preceding species. It is easily distinguished by its 
markedly convex shape, and the dense covering of slender 
soft papillae on the back, which give it a "pilose" appear- 
ance. The colour is usually white, but is occasionally 
brown or even black. There are from seven to nine large 
gills which are not retractile, and the oral tentacles are 
broad and flat. 

All these species are more or less common on the East 
Coast, and I have named them all because they are readily 
distinguished, and are worth careful study. There are a 
great number of other species, mostly rare or absent on the 
East, but in the Firth of Forth all those mentioned can be 
found without difficulty. They all occur also around the 
coast generally. 

While hunting for species of Doris, you are almost certain 
to find an animal very like a Doris in appearance, but of 
somewhat different shape, and of delicate pinkish colour. 
The body is smooth, oblong, and elongated, the foot project- 
ing markedly behind the cloak when the animal creeps. The 
cloak is almost a quadrilateral, and has a distinct keel down 
the centre. Its margin is reflected and indented posteriorly. 
There are thirteen simply pinnate gills which are not re- 
tractile. This is Goniodoris nodosa (see Fig. 73), a most 
graceful little creature, usually pink, speckled with white, 
but sometimes white or yellow. It reaches a length of 
about an inch, and is abundant everywhere under stones. 
The breeding season is in March (in the Firth of Forth), 
when the animals congregate in large numbers, and lay 
ropes of spawn, very different in shape from the frilled 
ribbons of Doris. This species lives fairly well in con- 
finement, and is a great addition to an aquarium, where its 


more active habits and graceful shape make it preferable to 
most of the species of Doris. 

The remaining Nudibranchs. are nearly all beautiful, both 
in form and colour, but are so numerous that we can select 
only those which are fairly common between tide-marks. 
Unfortunately, none of them have common English names. 

The first genus, Triopa, generally resembles Doris, but 
differs from it in the reduction of the gills, now only three 
in number, and the presence of slender outgrowths or 
processes at the sides of the back. In Triopa daviger, our 
only British species, the body is less than an inch long, and 
is white, variegated with bright yellow, a combination of 
colours which is very common among littoral Nudibranchs. 
It is an inhabitant of deep water, and is only rarely found 
between tide-marks. 

FIG. 73.Goniodoris nodosa. After Alder and Hancock. 

Another form, Polycera quadrilineata, is not uncommon 
near low-tide mark, and is singularly beautiful in appearance. 
It is pure translucent white, beautifully marked and spotted 
with, bright yellow and black, the yellow spots being 
arranged in four lines running down the sides of the body. 
The tentacles are non-retractile, and the head bears, in 
addition to them, four to six processes, white tipped with 
yellow in colour. There are seven to nine simply pinnate 
gills, and close to the gills at either side a single golden- 
tipped process. It is to these processes with their beautiful 
colouring that the animal owes half its beauty. I have 
found it not infrequently among zoophytes and corallines at 
low spring tides. It grows to a length of about an inch. 

A very similar but much smaller form is Ancula criatata 
(see Fig. 74), which is common between tide-marks in the 


Firth of Forth, especially in spring. Its colouring is similar 
to that of Polycera quadrilineata, but there is only one 
yellow line placed in the middle of the back. The yellow 
tips to the processes are also often much less bright, the 
animal at times being wholly white. It is easily dis- 
tinguished from the preceding form by the arrangement 
of the processes. These are absent on the head itself, but 
the stalks of the dorsal tentacles each bear two. There are 
three large bipinnate gills, and these are surrounded by a 
circle of yellow-tipped processes, instead of the two of 
Polycera quadrilineata. All these points are well shown 
in the figure. The animals live well in confinement, where 
they spend much of their time floating at the surface, back 

Fia. 74. Ancula cristata. After Alder and Hancock. 

The next form, Dendronotus arborescens, is regarded by 
many naturalists as the most beautiful of our sea-slugs. 
Its name and its beauty are both due to the fact that the 
back is furnished with numerous branched and brightly 
coloured processes, which make the creature look more like 
a dainty piece of seaweed than a living animal. Bright as 
the colours are, they harmonise wonderfully with the reds 
and browns of the corallines among which the animal lives, 
so that it is by no means conspicuous in natural conditions. 
Like most sea-slugs it is rarely if ever eaten by shore 
animals, so that the colouring, although it resembles the 
surroundings, can hardly be described as "protective," and 
it is certainly remarkable that colouring of this kind should 
be common among animals apparently rarely attacked by 


Although Dendronotus can hardly be described as com- 
mon between tide-marks, I have not infrequently found 
specimens there. They are, however, usually of small size, 
while specimens from deep water reach a length of two 
inches. As is the case with most of the shore inverte- 
brates, the animals breed long before they attain the maxi- 
mum size of the species, so that I have had specimens of 
under an inch in length which laid numbers of eggs in 
confinement. Facts of this kind are very apt to puzzle 
novices accustomed to land animals, whose life is more or 
less sharply divided into two parts an early period of 
growth, and an adult period of reproduction. It should 
be clearly understood that such a condition of affairs is rare 
among marine invertebrates, which have usually no definite 
limit of growth, and which begin to reproduce very early. 
The result of this is that statements as to size are often 
very deceptive, for the limit given is usually that observed 
by some authority on the particular group, and the animals 
of the area at your disposal may show great variation as 
compared with this standard. Thus in the Firth of Forth 
the common starfish grows to a size much larger than the 
limit usually given, especially when it occurs in the vicinity 
of extensive mussel beds. On the other hand, in many 
cases the sea-slugs which congregate for breeding purposes 
are all distinctly below the standard of size as determined 
for other areas. It is not perfectly clear why marine in- 
vertebrates should differ so markedly in this respect from 
terrestrial forms, but there is no doubt that on the whole 
the conditions of life are easier on sea than on land. The 
high specific gravity of sea-water renders the support of 
the body an easy matter, while in a terrestrial animal, such 
as an insect, living in a rare medium, any additional weight 
would probably be a matter of great importance, and the 
limit of advantageous size is fixed more or less precisely 
for each species. 

As to the special characters of Dendronotus, it has no 
gills of any kind, and the body is elongated, narrow, and 
prismatic in shape. The dorsal tentacles are placed in 
trumpet-shaped sheaths, which are prolonged into branched 
processes. Similar processes fringe the front of the head, 
and are arranged in tufts down the back. The body is 


some shade of red-brown, beautifully streaked and marbled 
with white; the processes are also red or crimson, the 
colour fading towards their tips as it does in most seaweeds. 
The animals are very active, continually creeping and twist- 
ing about. The eggs are yellowish in colour, and are laid 
in a close spiral with very narrow coils. I kept a pair in 
confinement for a long time, but rashly introduced a sea- 
anemone (Actinoloba dianthus) into their aquarium. In 
the course of their travels the sea-slugs crawled over part 
of the anemone, and it forthwith discharged its stinging- 
threads and killed the sea-slugs. They were not eaten, 
being, indeed, almost as large as the anemone, but simply 
killed, much to my sorrow, for they were beautiful pets. 

It has been supposed that it is an important part of the 
function of the branched papillae that they render Dendro- 
notus and its allies inedible ; but I can hardly believe that 
this is the whole explanation, for forms like Ancula cristata, 
which have relatively few papillae and no brilliancy of 
colour, are also severely let alone by most animals. The 
aquarium in which the Dendronotus lived afforded some 
interesting results as to relative immunity to attack. Its 
chief occupant was a young Norway lobster of beautiful tint 
and large appetite, not very easy to satisfy. It was fondest 
of shrimps, prawns, and young crabs of various kinds, but 
had a way of eating these rather trying to the feelings 
of the onlooker, so I liberally supplied it with various sea- 
slugs, of which at the time I had a large stock. Colourless 
specimens of Ancula cristata, small Dorids, Dendronotus, 
and others, which seemed less alive than crabs and quite 
suited to the lobster's taste, were placed in his dish. But 
though the coat of a young spider-crab was no protection 
against the voracity of the Nephrops, the delicate sea-slugs 
crawled untouched over his body, while he seemed only 
anxious to get out of their way. When the anemone came 
on the scene, however, the conditions were largely reversed. 
The crabs seemed able to resist its deadly power to a much 
greater extent than the defenceless sea -slugs, who fell 
victims at once; but in natural conditions the sea-slugs 
rarely live in those dark and dank localities which suit this 
particular anemone. The experiment showed in an interest- 
ing way that the value of a protective device depends upon 



the environment of the protected animal, and must have a 
direct relation to this environment. It seems probable that 
the sliminess of many sea-slugs, like that of some worms, 
may render them unpalatable to many foes. 

Much smaller than Dendronotus, but in its way quite as 
beautiful, is Doto coronata, a little animal occasionally 
found among corallines at the margin of the rocks. (The 
animal is shown in Fig. 4, p. 13, and the spawn in Fig. 75.) 
If you can pick it out from a dense cluster of the weed, you 
may natter yourself that your eye has been tolerably well 
trained. One specimen may be found by chance, but if you 
are desirous of obtaining several for examination, you will 
find the need of patience exceeding that of Job. Place 
your specimens on green weed or in a light dish, and you 
may wonder at their conspicuousness, put them back among 
the corallines and zoophytes and they seem to disappear 
from sight. Not only is there no definiteness of form, no 
difference of colour to catch the eye, but the colours are so 
arranged as to give that contrast of reddish pink and white 
so eminently characteristic of 
tangled tufts of coralline. 
The body is very small, with 
a pale ground colour and 
crimson markings; there are 
no gills, but the back bears 
five to seven pairs of very 
large papilla, each of which 
is covered with large tubercles, 
whose crimson colour stands 
out against the light tint of 
the papillae. The papillae are 
often described as resembling 
pine cones, and their shape 
and markings give them an 
apparent bulk out of all pro- 
portion to the size of the 
body. In confinement they 
are very apt to fall off at the slightest touch. The tentacles 
are very slender and spring from large trumpet -shaped 
sheaths. The animal lives on zoophytes and is strictly an 
inhabitant of deep water. I do not know the special value 

Fio. 75. Spawn of Doto coronata. 
After Alder and Hancock. 


of the resemblance to coralline, nor do I know what animals 
attack it under natural conditions. 

The next set of sea-slugs we shall consider belong to the 
very large genus Eolis (see Fig. 76), whose members often 
chiefly differ from one another in colouring, and are usually 
exceedingly beautiful. All are characterised by the simple 
slender papillae arranged in rows or clusters at the sides of 
the back. Most of them live among weeds and zoophytes, 
on the latter of which they chiefly feed. We shall consider 
here only a few of the commoner species. 

The common grey sea-slug (Eolis papillosd) is the largest 
of our species, and may reach a length of three inches, but 
is usually much smaller. The middle of the back is perfectly 
smooth, and in small, delicate specimens it is easy to see the 
beating of the transparent heart through the skin. The 
sides of the body are densely clothed with closely set 
papillae, arranged in more or less distinct rows, and usually 
greenish or brown in colour. As in the other species there 
are two pairs of tentacles a dorsal pair, here short and 
stout, and a ventral or oral pair beside the mouth. The 
colours are variable, but usually not bright, and the papillae 
so frequently fall off in confinement that the animal is 
hardly a desirable occupant of an aquarium. From its 
large size it can be dissected more readily than many of 
its allies, and dissection will disclose the curious fact that 
the stomach is much branched, its branches being continued 
into the papillae. 

The next species is much more beautiful, and is fairly 
common between tide-marks on the North-east Coast. It 
is called Eolis coronata, and is usually less than an inch 
long. The body is proportionately much more slender and 
elongated than that of the preceding species, and the 
papillae are arranged in transverse rows across the back 
instead of in dense masses at the sides. The dorsal tentacles 
are what is known as "coronated," being surrounded by 
spiral yellow projections of very characteristic appearance. 
The oral tentacles are very long and slender, and the anterior 
angles of the foot are produced. The body is a delicate 
pinkish white colour, but it is to the papillae that the 
animal owes its beauty. They are transparent, and traversed 
through the greater part of their length by the branches of 


the stomach, the result being that each is bright crimson 
in colour, tipped with white above the point where the 
branches of the stomach stop. In another light, however, 
the crimson part suddenly flashes out into the brightest 
blue optical colour, with a sheen like that of a bird's feather. 
In certain lights the little animal closely resembles coralline, 
while in others the blue tints make it stand out vividly. 
It is a most beautiful little species, and lives well in confine- 
ment. I have found it not infrequently at low spring tides. 
The next species Eolis rufibranchialis may justly be 
described as quite common, at any rate in the .Firth of 
Forth, where I have found numbers of specimens. It 
generally resembles the preceding species, except that the 

FIG. 76. Eolis rufibranchialis. Note the processes, or papillae, on the back, the 
two pairs of tentacles, and the minute eyes at the base of the upper tentacles. 
After Alder and Hancock. 

dorsal tentacles are transversely wrinkled, instead of 
distinctly coronated, and the papillae bright red in colour, 
with a white ring near the tips, and no trace of metallic 
sheen. The body is white. This is a very hardy species, 
and active in confinement. The general characters may be 
easily made out from the figure. 

There are a great many other species of Eolis on our 
shores, but those named are the commonest, and may serve 
to give an idea of the general structure and habits. Those 
who desire to pursue their observations further should 
consult the beautiful Monograph of the British Nudi- 
branchiate Mollusca, by Messrs. Alder and Hancock, or 
attempt to make a journey to the Newcastle Museum to see 
the original drawings of the last-named, which are among 
the treasures of the collection there. 


The sea-slugs are in many ways a most interesting group, 
and well worth careful attention. First as to structure. 
With the exception of Aplysia, all those we have named are 
without trace of shell; but this is not universally true of 
Opisthobranchs, for some of them have well-developed 
shells. The shell has indeed been gradually lost, as in so 
many groups of Mollusca. Then, again, the sea-hare has a 
typical gill like that of whelk or periwinkle ; Doris has a 
circlet of many gill-plumes, and these gradually decrease in 
number as in Polycera and Ancula, till we come to forms 
with no gills at all. Simultaneously with the disappearance 
of the gills we have the appearance and increase of the 
curious papillae, branched as in Dendronotus, or simple as in 
Eolis, which help to give the Opisthobranchs their quaint 
and beautiful shapes. Similarly, we see in passing from 
Aplysia towards the Eolids how the solidity of appearance 
which we are accustomed to associate with our shore 
Gasteropods gives way to a delicate translucency or trans- 
parency, and the dull tints of whelk or periwinkle to soft, 
bright colours, which are sometimes like those of the 
surroundings, and sometimes markedly different from these. 
Generally, we may say that the Opisthobranchs are a 
specialised group of Gasteropods, which in some cases have 
lost many of the Gasteropod characters, but which can be 
shown to have originated from typical forms with coiled 
shell, visceral hump, gill, and characteristic asymmetry. 




OPISTHOBRANCHS. Usually without shell, gill behind the heart. 

(1) Shell present, one lateral gill. 

Shell concealed, delicate, -\ 

single gill, 2 well- \Aplysia hybrida. 
developed epipodia J 

(2) Shell absent, gills plumose, placed round anus in mid- dorsal 

D. tuberculata, 9 tripin- 

' nate gills, tubercles 
numerous, round. 

D. johnstoni, 15 tripin- 
nate gills, tubercles 
minute, close-set. 

D. repanda, 5 tripinnate 
gills, tubercles small, 

D. bilamellata, numerous 
simply pinnate non- 
retractile gills, tubercles 
large, unequal. 

D. pilosa, 7 to 9 non- 
retractile gills, mantle 
with dense soft papillae. 

Body ovate, depressed,' 
mantle large, without I 
processes, coveringhead \-Doris 
and foot, dorsal ten- 
tacles retractile . 

Body elongated, mantle 
small, without pro- 
cesses, not covering 
head and foot, dorsal 
tentacles non-retractile 

Body elongated, mantle 
small, bearing lateral 
processes, gills 3, tri- 

Body elongated, mantle" 
indistinct, head with 4 
to 6 processes, gills 7 
to 9 with lateral ap- 
pendage at each side . 

Like Polyccra but with- 
out head appendages, 
except for 2 on the ten- 
tacles, and with only 3 
gills surrounded by pro- 


( Gf. nodosa, gills 13, simply 
' \ pinnate. 

Triopa claviger. 

-Folycera quadrilineata. 

Ancula, cristata. 


(3) Gills absent, processes numerous, simple or branched, tentacles 
with sheaths. 

Body narrow elongated,^ 

CcTed, = k'"" arb 
with branched sheaths] 
Body narrow and small, \ ID. coronata, processes 

Esses unbranched, In/ with 5 to 6 rows of 

and massive, ten- [ tubercles and a ter- 

5 in plain sheaths] [ minal one. 

(4) Gills absent, processes linear or fusiform placed along sides of 
back, tentacles 4 without sheaths. 

(E. papillosa, 18 to 24 
transverse rows of pa- 
pillse, body broad. 

Body elongated, tapering 


behind with numerous I Eolis 
simple papillae or pro- J 
cesses . . J 

E. coronata, papillae in 6 
to 7 clusters at each 
side, dorsal tentacles 

E. rufibranchialis, dorsal 
tentacles wrinkled, pa- 
pillae red in 6 to 7 


I. The Chitons, primitive forms very different from ordinary 

II. Zygobranchs, limpet-like forms. 

III. Azygobranchs, forms with coiled shell, single gill in front 
of heart. 

(a) Forms with unnotched shells, such as the periwinkles, the 

tops, and others. 

(b) Forms with notched shells, such as the whelks, dog-whelks, 

and others. 

IV. Opisthobranchs, forms often without shell, gill behind the 

(a) Forma with shells (Tectibranchs). Of these only the sea-hare 

has been described. 

(b) Forms without shells (Nudibranchs), the different kinds of 


The sea-hare is commoner in the South than in the North, and is 
said to be especially abundant at Weymouth and Torbay. Of the 
remaining sea-slugs described in this chapter, certainly the majority 


occur all round the coast, though their relative abundance varies 
greatly. In the West and South-west as indeed everywhere to a 
greater or less extent other species occur between tide-marks, but 
the forms mentioned may be sufficient to afford an insight into the 
chief modifications of external form in the Nudibranchs. Certain of 
the species of Doris are especially widely distributed and common. I 
have found singularly fine specimens of D. tuberculata in abundance 
between tide-marks, at such widely separated localities as Alnmouth 
and Aberystwyth. Many of the Nudibranchs, indeed, seem to be as 
universally distributed around our coasts as such familiar forms as 
the common shore crab, the mussel, cockle, shrimp, periwinkle, but 
in most cases the sea-slugs are less likely to be noticed than these. 


General characters of Bivalves Their classification The saddle-oyster 
and the mussels Their structure and habits Oysters, Pectens, 
and Lima Swimming power of Pecten and Lima Characters of 
Cyprina Mactra and its allies The Venus and carpet-shells 
The cockles The gapers Mya and Lutraria Rock-borers The 

THE next great group of the Molluscs is constituted by 
the Bivalves, or Lamellibranchs ("plate-like gills"), of 
which the oyster, mussel, and clam are familiar examples. 
In order to get a notion of the anatomy, it is well to obtain 
a living mussel and a living example of the bivalve known 
as the little carpet-shell (Tapes pullastra), which is very 
abundant on the rocks. The blue shells of the former, 
and the brownish yellow ones of the latter, are very 
common objects on most shores. Place both in water, and 
notice the two valves of the shell, united to one another 
by an area of greater or less extent known as the hinge. 
Notice that when the animals are at rest the valves gape 
slightly, allowing certain of the soft parts to protrude. But 
when alarmed they close their shells suddenly, sometimes 
sending out a sudden jet of water in the process. The way 
in which the shell is closed enables you to conclude at once 
that it must be the result of muscular action ; there are, in 
fact, large closing muscles, usually two in number, in all 
Bivalves, and they are very characteristic structures. 

Next study carefully the parts protruded in an open 
bivalve. Take the mussel first (see Fig. 77). As the shell 
gapes there appears at the part of the shell opposite the 
hinge a fringed mantle-flap (i in Fig. 77), which is double 



in correspondence with the shell whose valves it lines. At 
the straighter side of the shell there is protruded a slender 
white foot (/ in Fig. 77), by means of which the animal 
slowly moves. If allowed to remain undisturbed it ulti- 
mately anchors itself by a rope of threads, or byssus (b in 
Fig. 77), secreted from the foot, and serving to fasten the 
animal to the surrounding stones or shells. The byssus is 
rapidly formed, 
and can soon be 
renewed if torn 
away. At the 
side of the shell 
opposite to the 
foot it will be 
seen that the 
two parts of the 
mantle are fused 
together at two 

places a little ^ ia - ^ Edible mussel (Mytilus edulis). For letters 

distant from one 

another, so that a very short tube (e in Fig. 77) is formed. 
By placing the mussel in slightly turbid water, it is easy 
to see that in life there is a continuous current of water 
entering by a wide space between the halves of the mantle 
marked i in Fig. 77, and leaving by this short tube, which 
constitutes the exhalent aperture. The lower current brings 
with it food particles and the oxygen necessary for respira- 
tion, the upper current carries out the waste carbonic acid 
and the indigestible residue of the food. 

Turn next to the little Tapes, and you will find very 
similar conditions, save that the foot is of a different shape, 
and the two apertures are drawn out into long siphons or 
tubes, which can be protruded or retracted, and whose tips 
are beautifully fringed. A little observation will show that 
by the upper of these the water escapes, while it enters by 
the lower. Again, while the mussel must live freely ex- 
posed to the water, the carpet-shell, on account of its 
siphons, is enabled to live buried in sand or mud with 
merely the siphons protruding. Eefore proceeding to re- 
move the upper valve of your specimens to examine the 
anatomy, study some empty shells of the same or different 


species. In the mussel notice first that the two valves of 
the shell are of the same size (equivalve); this is very 
characteristic of Bivalves, and, together with the fact that 
each valve is inequilateral, is a convenient means of dis- 
tinguishing them from Brachiopods, or lamp-shells, which 

have inequivalve but 
equilateral shells. In 
other words, the shell 
of a bivalve is divided 
into two equal parts 
when the valves are 
separated, but not 
when the valves are 
divided by a median 

pi - n --^r^. ia eut 1 i ne \. The J she11 rf * 

Brachiopod, on the 

other hand, consisting as it does of two valves of unequal 
size, is divided into two equal parts only by a line which 
bisects the two closed valves. 

Again, the two valves of the shell of the mussel are 
united at the hinge by an internal cartilage called the 
ligament, so placed as to cause the shell to gape, except 
when it is forcibly closed by muscles. The hinge is over- 
hung by two projections, or beaks, which form the oldest 
part of the shell. In the inside of the shell are to be seen 
markings indicating the places where the muscles of the 
shell have been attached. In the mussel these are two in 
number, and are placed at the side of the shell opposite to 
that where the foot is protruded. In addition to these 
markings, there is an uninterrupted line near the margin of 
the shell which marks the line of attachment of the mantle 
to the shell. If the mussel shell be compared with that of 
Tapes, it will be seen that in the latter case this line of 
attachment does not follow uninterruptedly the margin of 
the shell, but is at one spot inflected to form a deep, 
rounded bay, called the pallial sinus. This sinus marks the 
attachment of the muscles which move the siphons, and its 
presence in a shell enables one to conclude at once that the 
living animal possessed siphons. 

The shell of Tapes differs in several other respects from 
that of Mytilus. Thus the hinge, instead of being smooth, 


is furnished in each valve with three projections, or teeth, 
which lock into corresponding cavities, in much the same 
way as that in which the bones of the skull in a mammal 
are locked together. Further, the ligament in Tapes is 
outside the shell, instead of being within it, and the two 
muscle impressions are more distinctly marked than in the 

Having by the study of the shell determined the position 
of the closing muscles, kill your living specimens by dropping 
them in hot water, slip a knife in between the valves, and 
cut through the muscles as close to the shell as possible. 
As soon as this is done, the elasticity of the ligament will 
cause the shell to gape, and the upper valve can be gently 
removed. If this be done carefully in both mussel and 
Tapes, the animal in each case will be seen lying covered by 
its mantle-flap, with the foot projecting more or less at one 
end, and the apertures, or siphons, distinct at the other. 
There is no head, but the mouth is placed at the opposite 
end to the apertures, or siphons, and usually lies at the 
more rounded end of the shell. It is immediately in front 
of the foot, and has two little flaps, or palps, at either side. 
On lifting up the mantle there will be found the plate-like 
gills, of which a pair lie at either side of the foot. Pro- 
jecting through the softer tissues will be also seen the firm 
closing muscles cut through when the shell was opened, and 
the foot, small in the mussel but large and distinct in Tapes, 
as in most common Eivalves. 

"We cannot enter in detail into the anatomy of the 
Bivalves they are difficult to dissect and to understand 
but it may be well to explain briefly what structures vary 
most frequently, and on what the usual classifications are 
based. In the first place, there is much and very obvious 
variation in the shell, in its shape, colour, and finer details. 
Almost all early classifications depended on the shell. But 
we have seen that the shell affords clear evidence as to one 
structural characteristic of the living animal, the absence or 
presence of siphons, so that a very early division is that into 
siphonate and asiphonate forms. Again, in some cases, as 
in Tapes, there are two distinct closing muscles, while in 
others one only is present. As this character can also be 
determined 'by the examination of the shell, it is very 


frequently used in the classification of Bivalves. Finally, 
the gills vary much in structure, being sometimes composed 
of free filaments, and at others woven into more or less 
compact, plate-like structures. We shall adopt here a 
classification based on this difference in the gills, for the 
following reason. There can be no doubt that the existing 
Bivalves have been derived from forms similar to, but 
simpler than, the less specialised of existing Gasteropods. 
The early Bivalves must have had simple, plume-like gills, 
similar to the gills of many Gasteropods, and the more 
complicated the gills of present Bivalves, the further have 
they departed from this primitive condition. The most 
natural classification seems, therefore, one based on the gills. 
As, however, we shall consider only such Bivalves as are 
likely to be found in the living condition, or are very 
abundant in the dry condition on the shore, we shall 
consider only three orders: (1) the Filibranchs, those with 
filamentous (or thread-like) gills such as the common mussel; 
(2) the Pseudo-lamellibranchs, those like the scallops, which 
have gills apparently of plate-like structure, but with the 
separate filaments so slightly attached that they fall apart 
very readily; (3) the Eulamellibranchs, the great majority 
of Bivalves in which the gills are firm plates, whose 
constituent filaments cannot be readily separated from one 

The first order includes the curious little saddle-oyster 
and the mussels, together with other forms which need not 
be considered here. The saddle - oyster, or silver -shell 
(Anomia ephippium), is common under stones between tide- 
marks, and exhibits several peculiarities of structure. The 
shell is fragile, pearly white in colour, and often irregular 
in shape. It consists of an upper convex valve, and a lower 
flat one perforated by a large hole beneath the beaks. The 
animals are extremely sedentary in their habits, growing 
fixed to rocks, but the fixation is accomplished in a some' 
what peculiar way. We have already explained that most 
Bivalves possess a byssus gland in the foot, which secretes 
a mass of silky threads serving to anchor the animal to 
surrounding objects. The saddle-oyster also possesses this 
characteristic gland, but both it and the foot are much 
reduced and apparently functionless. But nevertheless the 


animal does fix itself firmly to rocks, and it is of interest 
to notice how it accomplishes this. Of the two adductor 
or closing muscles which most Bivalves possess, one is here 
very rudimentary, while the other is large and conspicuous. 
From this large muscle a slip arises which passes through 
the hole in the lower valve of the shell, and is attached 
to the rock. Its end is furnished with a curious limy disc 
or operculum, formed by an aggregation of many little 
plates. In the living animal the shell, as usual, gapes to 
allow for the entrance of the necessary currents of water, 
and there is also, owing to the relaxed condition of the 
attaching muscle, a space between the lower valve and the 
rock. When the animal is alarmed the muscle contracts 
suddenly, the result being not only to close the valves, 
but also to drag the lower valve close against the rock. 
You will appreciate the meaning of this best by trying to 
peel the animals off the rock with your fingers, after they 
have been thoroughly alarmed. The method of attachment 
is very interesting, and offers some curious problems in 
origins to those speculatively inclined. Why should the 
saddle-oyster have given up its original method of attaching 
itself by a byssus? And if its peculiar method is advan- 
tageous, why should other sedentary forms have not adopted 
it ? There are many similar questions which one may ask, 
though I do not know if they can be answered at present. 

Saddle-oysters are very abundant on the shore, but on 
the East are usually of small size, the shells being often 
under half an inch in diameter. From their habit of closely 
accommodating their shells to the irregularities of the rock 
surface, they are very apt to be overlooked by careless 

We come next to the mussels, familiar forms, unfor- 
tunately burdened with a plethora of names. We shall 
describe three species, placed in as many different genera, 
viz. the edible mussel (Mytilus edulis), the horse -mussel 
(Modiola modiolus), and the marbled Crenella (Crenella 
marmorata). All three are nearly related, and are some- 
times placed in the same genus, or given other generic 
names. All are common, and may easily be found in the 
living state. 

The edible mussel is easily recognised, and has already 


been in large part described. It occurs in small numbers 
on most parts of the coast, but in favourable situations 
forms great mussel beds which are often carefully preserved, 
and are of considerable commercial value. Before the 
mussels can multiply with sufficient rapidity to form these 
beds, they must have abundant food and a suitable sub- 
stratum. For food they seem to depend largely on the 
finer refuse brought down by rivers, and they rarely nourish 
except where food of this kind is abundant. Where it is 
abundant, however, they occur in numbers which are liter- 
ally countless, as everyone who has seen a healthy mussel 
bed must know. In one respect such beds are peculiarly 
deceptive, as the unwary naturalist is likely to speedily 
discover. My own first introduction took place in the 
Firth of Forth, where a very low tide had laid bare a long 
stretch of thickly covered rocks, dotted here and there with 
huge starfish. Mindful of the tide, I hastened outwards 
with more speed than discretion, and, planting a hasty foot 
on a patch of mussels, found that it sank downwards over 
the boot-top in a mass of fine mud before it reached the 
firm rock. Later I learnt that this mud may reach a depth 
of many feet; so that it is distinctly unwise to rashly under- 
take the investigation of mussel beds. What happens is 
this the mussels attach themselves to a smooth rock, and 
by means of the fine cilia (whip -like threads) on the 
surface of the gills and mantle produce rapid inhalent 
currents. If the water contains many suitable solid par- 
ticles they flourish apace, digesting these, and passing out 
the indigestible residue in the form of fine mud. This mud 
accumulates rapidly and would soon stifle the mussels, were 
it not that as it is deposited they gradually lengthen their 
attaching threads, so that they rise above the surface of the 
rock. In still water the process may go on until the byssus 
threads reach a length of several feet, the space between 
the shell-fish and the rock being occupied by a mass of 
solid mud. The result is that although a flourishing mussel 
bed may be both useful and valuable, it is neither pretty 
nor sweet-scented. 

The large horse-mussel does not, strictly speaking, live on 
the shore rocks, but young forms are common there, and the 
shells of the adult are not infrequently found on the sands. 


The shell is larger and stouter than that of the edible 
mussel, and may be distinguished from the latter by the 
fact that the beaks are not terminal, but slightly to one 
side. The colour is very dark blue, almost black, and the 
shell is covered by a translucent membrane, or epidermis, 
which in the young is prolonged into a fringe. The byssus 
is very strong, and the animal entangles with it shells and 
small stones, so as to form a kind of nest. It lives usually 
in sand or mud in comparatively shallow water. 

The third mussel is a much prettier species, whose habitat 
renders it peculiarly interesting. The edible mussel spins a 
rope by which it fastens itself to stones or posts, the horse- 
mussel uses its threads to weave foreign objects into a 
protective nest, but Crenella marmorata finds shelter and 
safety within the tests, or outer coats, of sea-squirts 
(Ascidians). Into these it burrows deeply, so deeply that 
its presence can only be discerned by the resistance which 
the Ascidians offer to the touch. Ascidians of various kinds 
are common on most shores, often growing in masses beneath 
overhanging rocks. Frequently, also, they are torn up by 
gales, and strewn in repulsive-looking masses along the 
shore. If your ardour is not quenched by an unfavourable 
exterior, and is sufficient to lead you to tear open the tough 
cases, you are likely to find not only the curious Ascidians 
themselves, but also one or two specimens of the pretty 
green Crenella marmorata. It also occasionally occurs in 
nests like those of Modiola modiolus made of shells or 
stones. The shape is very characteristic, the shell being 
markedly gibbous, or swollen, and rhomboidal in shape. 
It is sculptured by fifteen to eighteen longitudinal ribs 
anteriorly, and by twenty to twenty-five posteriorly, the 
ribbed areas being separated by a smooth region. The 
beaks are small, swollen, inflected, and divergent. The foot 
is white and very long, and is used in leisurely progression, 
as well as in secreting the byssus threads. 

In the next order, the Pseudo-lamellibranchia, are included 
some exceedingly beautiful forms indeed, I have heard it 
maintained that one of them, Lima Mans, is the most 
beautiful of our common marine animals. Others of them, 
such as certain of the scallops, have always been prized by 
shell collectors for the bright colouring of their shells, 


which are usually marked in shades of red and pink. We 
shall consider in the order only three genera Pecten, Lima, 
and Ostrea all characterised by the structure of the gills, 
the absence of siphons, the single adductor muscle, and 
some other common characters. 

Of the scallops the most abundant is the common scallop 
(Peden opercularis), often seen in fishmongers' shops in the 
larger towns. There are few stretches of sandy shore where 
the separate valves of this species are not to be found, but 
living animals are not quite so easily obtained. Those sent 
to market are obtained by dredging, but where, as in the 
Forth, there are large scallop beds, it is quite common to 
find small living specimens on the shore rocks. After 
storms, also, living scallops are often cast up in large 
numbers on the shore, or are found living in the rock 
pools. Such specimens are often somewhat injured by their 
journey, and rarely live long in confinement, but small 
specimens from the rocks live well, and form charming pets. 
Select a few specimens about the size of a penny-piece, and 
carry them home to your aquarium, or domicile them in 
some rock pool. While you are admiring the beautifully 
sculptured and coloured shell, its valves will suddenly gape, 
and from the semicircular space so produced long, white 
threads will be protruded, which float freely in the water. 
Watch the opening shell carefully, taking care that your 
shadow does not fall on the water, and you will see that the 
two fringed mantle-folds are set round with jewels I would 
say, did not strict accuracy compel me to call them simple 
eyes. But jewels they are, nevertheless, if changing tint, 
with gleam of emerald and amethyst, may earn the name. 
It would not be easy to say how much the scallop really 
sees with them, but it is certain that it very speedily becomes 
aware of differences in the intensity of light, or of rapid 
movement. When it is alarmed in this way, it suddenly 
changes its position by flapping its valves together in a way 
which drives it through the water in a series of rapid jerks. 
This power of swimming is very characteristic of the 
scallops, and is a very curious sight. As they rest in the 
bottom of the pool or dish, they look as passive as any other 
bivalve, and when without apparent stimulus of any kind 
these passive shells suddenly spring upwards in the water, 


and by a succession of movements drive themselves a very 
considerable distance through it, the astonished onlooker is 
apt to receive something of a shock. It should be noted 
that the movement is not accomplished by the foot the 
characteristic organ of locomotion in the Mollusca but by 
shell and mantle. Nevertheless, just as Anomia has a small 
attaching byssus, although it attaches itself by another and 
quite different organ, so the scallop has a foot, although it is 
not used in locomotion. When your little scallops lie 
motionless at the bottom of the dish, you may see the 
slender, finger-like foot protruded at one side. It is capable 
of spinning a slender byssus, by means of which the animal, 
especially when young, temporarily anchors itself. 

When you have studied the living animal, and watched 
its curious flight, you should collect a goodly number of 
shells from the shore and proceed to study them in detail. 
It is well to have a considerable number of specimens, for 
there is a large amount of variation, especially in colour 
indeed, there are said to be no less than six colour varieties 
in the Firth of Forth alone. 

If your specimens consist, as often happens, of detached 
valves, you should first pick out and distinguish the upper 
and lower valves. Both valves are convex, but one is more 
convex than the other, and in natural conditions it is the 
less convex which is the upper. The difference between 
the two valves is, however, not marked, and the shell is 
therefore described as sub-equivalve that is, with nearly 
equal valves. It is also almost circular (sub-orbicular) and 
almost equilateral. Like that of all other Pectens, or 
scallops, it is furnished with two ears, here almost equal 
in size, and has a straight hinge line with a marginal 
ligament, and a central cartilage placed in a pit beneath 
the beak of each valve. The special characteristics of the 
species are found in the number of the ribs (about twenty) 
and the peculiar structure of the surface of the shell. It 
is covered with close rows of minute scales, which require 
some little attention before they can be seen, but once the 
shell has been closely studied it is almost impossible after- 
wards to mistake the species for any other. In the 
commonest colour variety the shell is red-brown marked 
and spotted with white. 


The common scallop is not the only edible species of 
Pecten^ for the much larger P. maximus, often called a 
clam, is not infrequently seen exposed for sale. It is a 
very handsome species, reaching a size of six by five inches, 
and often of a pale colour beautifully mottled with pink. 
The valves are very unequal, the lower being deeply convex 
and the upper almost flat, except for a slight concavity near 
the beak ; it is always much darker in tint than the lower 
valve. The convex lower valve bears fourteen to sixteen 
broad, rounded ribs, wider than the spaces between them. 
In the upper valve the relation of ribs and spaces is reversed, 
so that the two valves lock closely together, a condition 
which may be noticed in many Bivalves. The ears are 
nearly equal, but are concave in the upper valve and convex 
in the lower. The surface of the shell is quite without the 
scales of the preceding species, but is marked by distinct 
radiating striae, which with the broad ribs are very character- 
istic of the species. Separate valves of this species are not 
uncommon on the shore, but I have never found the entire 
animal, either living or dead. Specimens for dissection may 
be obtained at times from the fishermen. The shells are 
sometimes used by cooks, and are very commonly sold in 
fishmongers' shops at a penny apiece, but unfortunately it 
is usually only the convex lower valves which can be 
obtained in this way. 

We shall mention one other species only, one which is 
interesting because, like the oyster, it is fixed when adult, 
and, as in the oyster, the shell is often curiously distorted. 
This is P. pusio, odd valves of which may be often found on 
the shore. The animal is attached by the lower valve, 
which is usually white, without sculpture, and often of very 
irregular shape. The upper valve has its surface covered 
with very numerous (40-80) prickly ribs, often alternately 
large and small. In the young the ears are unequal in 
size, and in the adult they become very irregular. 

The next genus is the very beautiful one of Lima, of 
which we shall consider one species only the delicately 
tinted L, hians. Strictly speaking it is beyond our range, 
but is such an interesting and beautiful species, and so 
common in the Clyde, that we must make an exception in 
its favour. In it the shell is snowy white, and the mantle a 


lovely pink. It swims in a way which casts the efforts of 
the scallops into the shade, and as it jerks rapidly through 
the water it trails behind it a long mantle-fringe of rosy 
pink, forming altogether a picture which once seen is 
not easily forgotten. My own first experience of it was a 
memorable one. It was on my first dredging expedition, 
and the scene was the broad waters of the Clyde. The 
wind blew strong and fresh, dashing the salt spray over the 
side of the little yacht, as she heeled under the pressure of 
her heavy dredge; but it was not strong enough to damp 
the ardour of the enthusiasts, who clung desperately to any 
available rope in their anxiety lest some treasure should 
escape their notice. There were many treasures in the 
heavy net, but perhaps the greatest were the rough-looking 
masses of stones, shells, and weeds fastened together by 
byssus threads, which we were told were the nests of Lima. 
When carefully broken, these nests disclosed the animal 
itself lying snugly in the centre. They were dropped into 
jars of clean water, and instantly began to swim rapidly, 
trailing their beautiful fringes behind them. They would 
be beautiful in any situation, but seen against a background 
of blue hills, with the fresh breeze in one's face, the blue 
waters around, and the rocking boat beneath, there was 
certainly an added charm. For my own part I cannot 
think that a thousand daffodils can be so fair a sight as half 
a dozen Limas, let the yellow bells dance never so merrily. 
The memory of that first day has at least made the animals 
particularly dear to me. 

This particular species, L. Mans, does not occur on the 
East Coast, so a journey must be made to the "West to find 
it. The shell shows much general resemblance to a scallop, 
but is longer in proportion to its breadth, and has less 
prominent ears than most scallops. The shell gapes at both 
sides, and is marked by numerous fine radiating lines, 
crossed by other concentric lines. The animal also shows 
much resemblance to a scallop, but its tentacles are much 
longer and more numerous, and the curious habit of nest- 
building also affords a contrast. Except in the extreme 
South the animal is confined to deep water. 

The third genus of the order, that of the oyster, is of 
more interest to the epicure than the shore naturalist. The 


edible oyster (Ostrea edulis) is related to the scallops, but 
differs in its peculiarly sedentary habit with which is asso- 
ciated the distorted and ugly shell, in the entire absence of 
foot and byssus, and in some other characters. Just as 
many domestic animals acquire their culinary value at the 
expense of almost all the qualities which make them in- 
teresting to the naturalist, so the oyster pays for its valued 
qualities by the absence of the beautiful shell, the power of 
active locomotion, the quick senses, and the other qualities 
which make the Pectens and Limas so fascinating. Those 
who are not epicures may perhaps be forgiven for regarding 
a luscious oyster as about as attractive as a prize pig, 
while . those to whom it. appeals as an article of diet will 
probably mourn with the famous conch ologist that oysters 
grew and died in countless numbers before ever men 
existed to enjoy them. There can be no difficulty in recog- 
nising an oyster if one should be found, which is not very 
likely. The chief point of interest is the curious shapes 
which the shells assume when subjected to pressure by sur- 
rounding objects. The animals are incapable of locomotion, 
and^are attached by the surface of the lower valve, for the 
ftyssjijs gland has been completely lost. 

tf -'* r FtS. third order of Bivalves, the Eulamellibranchia, in- 
cludfe$ the greater number of living forms. Its members 
are classified according to the presence or absence of the 
siphons, the amount of union of the mantle-folds, the 
characters of the gills, and some other points. Most of 
them live buried in sand or mud, and the development of 
siphons is an adaptation to this habit. Their degree 
of development is reflected in the shell in the condition 
of the pallial sinus (see p. 268), and where, as in the My as, 
they reach a great size, they cannot be completely with- 
drawn into the shell, and this "gapes" permanently. From 
the habitat usually sand or mud these Bivalves are rarely 
conspicuous on the shore rocks ; many may be obtained by 
systematic digging near low-tide mark, others are tossed on 
the beach after storms, but the majority, even of the 
shallow-water forms, are familiar only in the condition of 
shells. As our concern here is rather with living animals 
than with "shells," we shall describe relatively few Bivalves, 
chiefly those which may be hoped for in the living condition. 



). Left valve of shell of Cyprina islandica, to 
show markings of interior, b, beak of shell ; t, one 
of teeth ; o, anterior adductor muscle ; p, posterior 
adductor ; I, ligament ; m, mantle-line. 

As an example of one of the simplest Eulamellibranchs 
we may take Cyprina islandica (see Fig. 79), which is often 
very abundant in the living condition after storms. It has 
practically no siphons, the mantle-folds are widely open, and 
the pallial line is 
simple, without 
trace of sinus. The 
shells are large, 
triangularj and 
convex; they are 
sometimes used as 
scoops, and .called p 
"sugar - shells." 
The surface of the 
shell displays ad- 
mirably a struc- 
ture which we 
have not yet ex- Fm . 
pressly noted, and 
that is the layer 
called by conch- 
ologists the epidermis. The shell of a Mollusc is made 
of three layers, an external organic layer without lime, the 
epidermis, a prismatic layer forming the bulk of the shell, 
and an internal pearly layer, often absent, but sometimes 
very well developed. In many shells the epidermis is early 
rubbed off, exposing the prismatic layer, which is often 
brightly coloured externally; but in Cyprina it is thick and 
persistent, giving the shell its characteristic brown colour. 
The shell is heavy and massive, obliquely triangular, and 
swollen towards the beaks. It is marked by numerous fine 
concentric lines, and is covered by the brown epidermis. 
The teeth are well developed, there being three cardinals, 
or central teeth, in each valve, and a single lateral. The 
interior of the shell is smooth and chalky white. This 
combination of characters makes the species readily recog- 
nisable. The animal lives in muddy sand, in which it 
burrows by means of the large foot. It is sometimes used 
as bait. 

In the next sub-order, which includes such important 
genera as Mactra, Tellina, and Donax, the siphons are long 


and the pallial sinus deep. Of the three genera named, 
the species of Mactra are most commonly found in the 
living condition, and are also very common as shells on the 
beach at all seasons. Two of the species, M. solida and 
M. subtruncata, are very much alike, and not easy to dis- 
tinguish from a description merely ; while the third species, 
M. stultoruwi, or Fool's Mactra, is readily recognised, and 
cannot be confused with any other shell. In all cases the 
shells are triangular, and are characterised by the almost 
smooth surface and the nature of the teeth. Of these there 
are two thin cardinals in the right valve, and two similar 
but united cardinals in the left; the laterals are large and 
laminar, there being two on each side in the right valve 
and one on each side in the left. In Mactra solida the 
shell is solid, opaque, and perfectly triangular, the sides 
being equal ; the surface is marked by concentric striae and 
is yellowish white in colour, often stained by substances 
derived from the sand. It is not easy to point out dis- 
tinguishing differences from M. suUruncata, but the latter 
is smaller, more convex, and seems to be hollowed out at 
either side of the beaks, so that 
these become more prominent. In 
M. stultorum the shell has the same 
shape as in M. solida, but is thin, 
delicate, glossy, and almost smooth. 
The colour is a pale brownish tint, 
variegated by longitudinal rays of 
reddish brown. The shell is very 
familiar, and is represented in all 

FIG. 80. Mactra stultorum. ,-, ,, ,. * , ., , ,, 

the collections of children; the 

other species, on the other hand, being thick and clumsy, 
are often neglected. 

As members of the same sub-order we may mention two 
other forms, abundant as shells, but not commonly found in 
the fresh condition. One of these is Donax vittatus, the 
purple toothed-shell, an active little form which lives in 
sand near low-tide mark, whose shells are greatly prized 
by children both for their beauty and colour varieties. The 
living animal is both interesting and beautiful, the foot 
being large in proportion to the body, the mantle delicately 
fringed, and the siphons, which are quite separate, marked 


with longitudinal lines and delicately fringed at the tip. 
The shell is small, at most an inch long, and some half-inch 
broad. It is oblong and beautifully glossy and polished, 
the surface being marked by fine longitudinal striae. The 
inner margin is strongly notched, and the inside of the shell 
is usually stained with violet. The colours of the outer 
surface are varied, usually shades of violet, brown, or 
yellow, but it is sometimes almost white. 

An even prettier and more delicate shell is the little 
Tellina tenuis, which, thin and fragile as it is, is often 
tossed up intact after a storm. The shell is often pure 
rose-pink, sometimes pure white, sometimes yellow or 
orange. It is so much flattened that one might fancy the 
animal would hardly have room to live inside, and so thin 
that it can hardly afford much protection. The ligament is 
very thick and prominent, the teeth small. The shell is 
oval and semi-transparent. There are various other species 
of Tellina, some of them common but mostly small, and 
not to be found in the living state. 

Another sub-order includes the Venus and carpet-shells, of 
which there are a number of species. The species of Venus 
are very numerous, and can be recognised by their triangular 
or rounded shells with distinct concentric ribs. It may, 
however, be sufficient if we name one species, common at all 
seasons as a shell on the shore, and to be found living in 
sandy places. This is Venus striatula, a small shell measur- 
ing about an inch each way. The animal has fairly long 
siphons united for the greater part of their length, a thick 
foot slightly bent, and mantle-folds open in front. The 
shell is pale-coloured, but usually marked by three bright- 
coloured longitudinal rays of reddish tint, which cross the 
strongly marked concentric ribs. A point of interest about 
the animal is that it seems to be greatly relished as food by 
some of the whelks, for most of the shells found on the 
shore are perforated near the beak, showing that the whelk 
has drilled a hole through it, as a preparation to the devour- 
ing of the contained animal. 

Of the little carpet-shell (Tapes pullastra) we have already 
spoken ; it occurs very commonly on the rocks in sandy and 
muddy places. The shell is rhomboid in shape and solid in 
texture; it is marked by very numerous close set bands 


crossed by fine longitudinal striae. The colour is yellowish 
white, variegated with reddish brown. There are three 
cardinal teeth in each valve. A prettier species with more 
distinctly marked ribs, and streaks and patches of bright 
colour, often occurs on the shore in the dead condition. 
This is T. virgineus, which inhabits somewhat deeper water 
than the common species. The latter lives well in confine- 
ment, and affords an admirable object for the study of the 
siphons. When alarmed, the animal suddenly retracts these, 
producing a very forcible jet of water as it does so ; when it 
is lying undisturbed the course of the breathing currents 
can be clearly seen, especially in water containing suspended 

The next sub-order includes the cockles, which have a 
greatly elongated foot, used in taking "leaps," and also in 
burrowing in the sand. There are a considerable number of 
cockles, but as the differences between the species are not 
very well marked, it may be sufficient if we describe the 
common, or edible cockle (Cardium edule). This species, as 
is well known, occurs in beds in sandy and muddy ground, 
living on, or only slightly below, the surface. It is valued 
both as food and bait, and is collected by the fisher folk in 
large quantities, short rakes being used for the purpose. The 
shell is equivalve, somewhat triangular, and strongly convex. 
The characteristic cockle appearance is produced by the sculp- 
ture, which consists of twenty-four to twenty-eight flattened 
ribs separated by narrow furrows. These ribs project at the 
margin, as in all cockles, so that the valves lock closely 
together; in the living animal the mantle is fringed with 
delicate processes corresponding to these ribs. In an empty 
shell the internal characters can be made out, the fluted 
margin, the muscle scars, the strong central (cardinal) tooth 
in each valve, shaped like a reversed V, and the small 
laterals at each side of this. The different cockles are 
distinguished chiefly by the sculpture of the shells, and the 
number and shape of the ribs; generally speaking all are 
readily recognised as cockles. 

We come next to two genera whose members show some 
marked resemblances, combined with distinct differences. In 
both the large siphons cannot be completely retracted, so that 
the shell "gapes" permanently, and cannot be closed. 


The first genus the old maid shells, or Myas includes 
two common species which live buried in sand near low- 
water mark, and often occur in large numbers on the beach 
after storms ; the empty shells are to be found at all seasons. 
In both the siphons are large, invested in a common sheath, 
and united throughout their length. The shell is oval or 
oblong, and gapes at both ends. The hinge -cartilage is 
wholly internal, and is placed between a cavity in the right 
valve and a hollow in a conspicuous process of the left 
valve. The internal position of the cartilage and the 
presence of the large cartilage in the left valve make the 
shell of a Mya easily recognised. The shells are solid, 
opaque, not glossy, and with little brightness of tint. The 

FIG. 81. Mya truncata, showing siphons and foot. 

two species are Mya arenaria and Mya truncata, chiefly 
distinguished by the shape of the shells. In M. arenaria 
this is oblong, and about twice as long as broad; in 
M. truncata it is oval, and the length bears to the breadth 
about the proportion of five to four. In the latter, further, 
the posterior end of the shell is abruptly truncated ; in the 
former it is wedge-shaped. Both are used as food and bait, 
and are greatly relished by seagulls, who may be found 
feasting on them after storms. 

The other genus includes the otter-shells (Lutraria), of 
which we have one common species, L. ettiptica, which 
inhabits the same localities as the Myas, and is to be found 
with these after storms on the shore. The siphons are very 
long, and are inclosed in a common sheath, but are not 
completely united. As in Mya, the shell gapes at both 
ends, but it is much thinner, and is glossy and brightly 
coloured. The shape is elliptical and compressed, the car- 



tilage internal placed in a deep pit, the teeth consist of two 

diverging cardinals in each valve and two rudimentary 


We come next to the razor-shells, or Solens, interesting 
Bivalves which cannot be confused with 
any others, and which are very common, 
though not often seen in the living 
state. They live near low-water mark, 
where they burrow deeply in the sand, 
but may be readily dug out by an expert 
digger. We have two common species 
Solen siliqua (see Fig. 82), the common 
"razor-fish," in which the shell is almost 
straight and the ends are both abruptly 
truncated, and S. ensis, which is much 
smaller, distinctly curved, and has the 
anterior end more rounded than the 
posterior. It is unnecessary to describe 
the shell, for this must be familiar to 
everyone ; but it should be noticed that, 
like those of Mya and Lutraria, it gapes 
widely at both ends. The shape of the 
foot is interesting, and its efficiency as 
a burrowing agent should be noted on 
the shore; it will be noticed that its 
general appearance varies much, accord- 
ing as it is in action or at rest. It 
protrudes from the anterior extremity 
of the shell, and the united siphons 
from the posterior. When the animal 
is undisturbed these are protruded at 
the surface, and have the usual func- 

The two last Bivalves we shall con- 

FIG. 82. Razor -shell sider make their homes not in sand or 
(Solen siliqua). /.foot; mu( j k u t i n rocks, into which they 

at the other end the . , . ' . J 

siphons (s) are visible, burrow deeply. Ihese are Saxicava 

rugosa and the species of Pholas. The 

first is abundant everywhere, wherever suitable rocks 

occur. It is common in limestone, which is often literally 

honeycombed by its burrows. The blocks are thus ren- 


dered less resistant to wave-action, and are torn off from 
the solid mass of rock. They are then often utilised in 
rockeries, and on the East Coast it is common to find these 
built of such honeycombed stones still retaining the little 
shells. In the living condition the animal is very common 
on the shore, where its bright red siphons are to be seen 
protruding from rock surfaces. When touched they eject 
a forcible jet of water and then disappear. By breaking 
the rock, specimens can be obtained without difficulty, the 
shells though small being solid and not readily broken. 
They are oval in shape and gape at the posterior end ; the 
colour is white, and the shells generally without much 
beauty. It seems unnecessary to describe the details, as 
the bright red siphons and the habitat form very distinctive 

Even more interesting are the species of Pholas, which 
have singularly beautiful shells. One species, P. crispafa, 
is exceedingly common in the Firth of Forth, where it 
excavates the shale in all directions. Some of its charac- 
ters have already been noticed in Chapter I., so we may 
confine ourselves here to some details of the shell. As in 
all species, this gapes widely both in front and behind; there 
is no ligament nor teeth, but there is an accessory valve, or 
dorsal shield, beside the hinge; the hinge-plate is reflected 
over the beaks, and the shell is divided into nearly equal 
parts by a broad oblique furrow. Of the two regions so 
formed the anterior is furnished with about twenty rows 
of overlapping prickles, supposed to be of great importance 
in boring ; the posterior region is quite small. The whole 
shell is pure white and very brittle, so that a little care is 
necessary to obtain uninjured specimens. Another species, 
P. Candida, also occurs in shale, but may be distinguished 
by the absence of the furrow, the prickles covering the 
whole surface except a space at each end. 

We have now mentioned most of the Bivalves likely to 
be found living between tide-marks. Of the Mollusca there 
still remain the Cephalopoda, or Cuttles, specialised forms 
in which the foot has grown up round the head and become 
split into eight or ten sucker-bearing arms. Other character- 
istic structures are the funnel, through which jets of water 
can be ejected, thus producing motion, and the ink-bag, 


whose contents produce a dark cloud in the water. The 
cuttles are powerful animals and active swimmers; except 
at the breeding season they are rare between tide-marks. 
In the early months of the year a large form, Ommastrephes 
todarus, is common on the beach after storms on the East 
Coast, but this is due to the fact that at this time the 
animals come shorewards to lay their eggs. The spawn, 
both of this form and of Loligo vulgaris, is not uncommon. 
The former consists of somewhat pear-shaped masses, each 
containing many eggs embedded in jelly and fastened in 
dense clusters to weed. In the latter case the eggs are 
arranged in long tubes, which are similarly attached in 
clusters to weed. The animals are, further, at times repre- 
sented by their "pens," which are internal structures 
corresponding to the "bone" of the squid (Sepia), and 
probably to the last remnant of the shell which the early 
cuttles possessed. The pens of Loligo and Ommastrephes 
are horny structures, not unlike a quill pen, and reaching 
a length of a foot or more. 

In a living cuttle the beautiful changing tints should be 
noticed, the arms and suckers, the jets of water which are 
ejected from the funnel, and in natural conditions drive the 
animal backwards, the fins fringing the body, and the large 
eyes. A dead specimen will show the strong parrot beaks 
within the mouth, the gills within the mantle-chamber, 
and the ink-bag. The special characters of Ommastrephes 
todarus are as follows : The fins are placed at the posterior 
end of the body; the two long arms are nearly as long as 
the body ; the eight short arms have two rows of suckers ; 
the cornea, or transparent skin over the eye, has a central 
hole, so that the sea-water gains access to the anterior 
chamber of the eye. The animals reach a length of over 
a foot. Between tide-marks in the South a pretty little 
octopus, or form with eight arms, is at times to be found. 
This is Eledone cirrosus, a very charming little creature. 
On the shores of the English Channel the common octopus 
(Octopus vulgaris) is at times abundant in the vicinity of 
the shore. 




(1) Filibranchs, with filamentous or thread-like gills. 
Shell of irregular ^ 

shape, lower valve V Surface scaly, without ribs Anomia ephippium. 
with aperture . J 

'Shell wedge - shaped, % 

beaks terminal, colour I Mytilus edulis. 
blue . . . J 
Shell oblong, swollen in^ 

front, beaks anterior, \Modiola modiolus. 
colour dark purple . J 
Shell short and tumid, ^ 

CS$! <" """ 

yellow . . . J 

(2) Pseudo - lamellibranchs, gill -filaments only slightly attached 

Shell equivalve, oval 
or oblong, beaks 
incurved, hinge" 5 
without teeth 


Shell suborbicular, inequi- 
valve, marked with ribs, 
beaks with distinct ears, 
shell not gaping, brightly 



Ribs 20, surface with minute 

scales P. opercularis. 
Ribs 14 to 16, surface with 
radiating striae P. maxi- 

Ribs 40 to 60, prickly on 
upper valve only P. 
> pusio. 

Shell like the above, " 
gaping, colour white, 
valves equal 
Shell irregular, ineq ui valve, ^ 

upper valve flat and lower \ Ostrea 
concave, teeth absent . J 
(3) Eulamellibranchs, gills plate-like, the filaments firmly attached 

(a) Shell closed. 
Shell oval, with distinct 1 
epidermis and external I 
ligament, no pallial f W rina 
sinus . . . . J 

" Shell solid and opaque, 

triangular M. solida. 
Similar, but smaller, more 
convex, and with more 
prominent beaks M. 

/Shell oblique, gaping widely 
' \ at both sides L. Mans. 

{Shell round in young, and 
later becoming irregular 
0. edulis. 

f Shell obliquely triangular, 
-j swollen towards beaks 
v C. islandica. 

Shell triangularly oval, 
slightly striated, with 
deep sinus, cartilage 


Shell thin, glossy, with 
brownish rays M. stul- 



Shell wedge - shaped, 'j 
smooth glossy, with I D 
external ligament and j 
deep sinus . . . J 

Shell compressed, rounded ^ 
in front, angular and j 
slightly folded behind, V Tellina 
ligament external, pro- j 
minent . . . . J 

Shell rounded, solid, with ^ 

concentric ribs and small V Venus 
sinus . . . . J 

Shell oblong, beaks an- ^ 
terior, margin smooth, 1- Tapes 
sinus deep and rounded . ' 

Shell convex, triangular, 
with radiating ribs, 
notched margin and 
fluted interior. Beaks 
prominent, incurved 

(b) Shells gaping. 

Shell oblong, valves un- 
equal, left valve the 
smaller, with large carti- 
lage process . . . . 

* Cardium 


Shell oblong, two diverging \ T , lfrnr { n 
cardinals in each valve . / Lutrana 

Shell elongated, cylindrical, ) , 
margins parallel. .} Solen 

Shell rhomboidal, wrinkled, j Saxicava 
truncated . . .J 

Shell white, opaque, with } 
rows of prickles, acces- I 
sory valves or shields j 
present . . . .J 


Margin strongly notched, 
interior stained with 
purple D. vittatus. 

/ Shell thin, glossy, semi- 
\ transparent T. tenuis. 

f Shell triangular, inside 
J margin notched, except 
j at posterior side V. 
\ striatula. 

{Shell solid and opaque, 
marked by numerous 
fine concentric bands 
T. pullasf.ra. 

f Ribs 24 to 28, furrows nar- 
\ row C. edulc. 

Shell oblong, twice as long 

as broad M. arenaria. 
Shell oval, abruptly trun- 
cated behind M. trun- 

i Shell compressed, elliptical, 
! brightly coloured L. 
[ elliptica. 

/ Shell straight S. siliqua. 
\ Shell curved S. cnsis. 
f Shell small, about 1 inch 
\ long S. rugosa. 

{Shells divided by furrow, 
20 rows of prickles on 
an terior side P. crispata. 
Shell not divided, 25 to 30 
rows of prickles P. Can- 


The Bivalves described in this chapter are, generally speaking, those 
which may be expected to occur at all parts of our coast, so that little 
can profitably be said as regards distribution. It is obvious that such 
forms as the edible mussel and cockle cannot from their habits be 
expected to occur, in any abundance at least, except where shallow, 


estuarine waters are available. This is true to a less extent of other 
sand- or mud -inhabiting forms which are naturally rare off rocky 
coasts, and abundant on sandy beaches. But as sand and mud are 
derived from rocks, it will be found that even neighbourhoods which 
seem to be exclusively rocky exhibit somewhere stretches of sand 
haunted by the common bivalves. A good example is the long stretch 
of sand in the vicinity of Woolacombe, on the north coast of Devon, 
where are to be found quantities of shells apparently absent from the 
neighbouring rocky beaches. Similarly, the species of Pholas to be 
found vary with the composition of the rocks, for many species stick 
to one particular kind of rock. As to further detail, we may notice 
that Lima Mans can only be expected between tide-marks in the 
extreme South, and does not occur on the East Coast. On the other 
hand, the brown Cyprina islandica is a Northern form, diminishing 
in abundance as one passes southward. As regards the relative 
abundance of the others, it should be noticed that in the vicinity of 
fishing- villages the abundance of the shells of a particular species on 
the beach depends largely on the fact that the species is used as bait. 
The habits of the fishermen in regard to the bait used differ much at 
different parts of the coast, so that a great accumulation of shells of 
Cardium, Afactra, Mya, Cyprina, or Lutraria. at different parts is 
not in itself a proof of the predominating abundance of the particular 


Vertebrates and Invertebrates Structure of a sea-squirt Some com- 
mon forms Characters of fish The saithe, or coal -fish Sea- 
scorpions, or bull-heads Fishing- frog The lump-sucker and its 
eggs Shanny, butter-fish, and blenny, their habits and structure 
The sticklebacks Sand-launces Flounders, plaice, and other 

ALL the animals we have hitherto studied have been 
J\. without a backbone, or equivalent supporting-rod down 
the back, have had a ventral instead of a dorsal nervous 
system, and therefore, because of these and some other 
reasons, all belong to the INVERTEBRATES. The VERTEBRATES, 
or backboned animals, are most obviously represented on 
the shore rocks by the fishes, of which not a few species 
occur in the deeper pools. But there is in addition a group 
of animals which, despite appearances, have some claim to 
kinship with the great Vertebrate stock. These are the 
sea-squirts, or Tunicates, which in larval life have a more 
than superficial resemblance to tiny tadpoles. In adult life, 
on the other hand, they diverge very widely indeed from 
the Vertebrate ideal, being little more than sacs of jelly 
with a tough, transparent coat. 

Tunicates are common everywhere between tide-marks, 
but the majority are small, so that we may have to hunt for 
some time before finding a specimen of suitable size for a 
first essay in dissection. In some shady nook, or under an 
overhanging rock, you may find a flat, shapeless mass, 
attached by one of the flat sides, and of a general greenish 
tint. Peel it cautiously from the stone, disregarding the 
sudden jet of water by which it shows resentment of the 



process, and place in a pool or dish. In a minute or two 
the shapeless creature recovers sufficiently to stretch itself 
out in the water, and show at one end two elongated tubes, 
placed close together, of which the one shows eight, and the 
other six, red pigment spots close to the fringed openings, 
which are of yellowish colour. The creature has a soft, 
greenish coat, sufficiently translucent to allow one to see 
through it the distinct muscle bands of the underlying 
body-wall. By means of these bands it can retract its 
tubes or siphons, and contract the whole body suddenly on 
an alarm, the test, or coat, being so soft as to offer no 
hindrance to the process. In this respect, Giona intestinalis, 
as this particular Tunicate is called, differs from most of 
its allies, which have generally such stiff coats that their 
activities are limited to that sudden ejection of water which 
gives them their common name of sea-squirts. When not 
alarmed, Giona lies passively at the bottom of the dish, and 
it can be seen that a continuous flow of water passes in by 
the one siphon and out by the other. With a little care 
the internal anatomy can be made out, the Tunicates being 
usually fascinating creatures to dissect. As an aid in the 
process, a figure is given of a Tunicate from fairly deep 
water, in which the coat and tissues are so transparent that 
the internal anatomy can be made out without dissection. 

Any Tunicate has outside the body the coat, or test (t), 
made of a substance apparently identical with plant cellu- 
lose, and varying greatly in thickness, colour, and con- 
sistency. It can be very readily peeled off to show the 
animal within. This has a thin muscular body-wall, usually 
traversed by a network of slender muscular fibres, which in 
Giona are collected in definite bands. The body has no 
definite shape ; in Giona it is elongated, varying in length 
from about two to five inches, but it is often rounded or 
quadrilateral. In Giona the two apertures already noticed 
are near together, and between them there is a little yellow 
mass with a few radiating threads. This is all that repre- 
sents the nervous system so small and undeveloped that 
one can have few scruples about hurting a sea-squirt's 
feelings ! It is hardly probable that it can ever suffer from 
" nerves." 

Whatever the shape of the body in a Tunicate, tho 



greater part of it is always filled up by the large branchial 
sac (&?), which usually runs from the mouth or upper 
opening to the other extremity of the body. It is a 
beautiful structure made up of bars crossing one another 
at right angles, the rectangles so formed being filled up by 
smaller bars with slits between them. The whole sac is 
thus a sieve, but a sieve of beautiful and elaborate struc- 
ture. To the exterior this sieve opens by the mouth (w), 
and in life a continuous stream of water passes into it, then 
through the slits into the space between branchial sac and 
body-wall, and out by the lower (atrial, at) opening which 

communicates with this space. 
As the current passes through 
the slits of the branchial sac 
it washes the blood contained 
in the bars, which are really 
blood-vessels. The current is 
thus primarily respiratory, but 
it brings with it also the 
minute particles on which the 
sea-squirt feeds. These par- 
ticles would be swept out 

FIG. 83. Corella parallelogramma, a with the Water of respiration 
simple sea-squirt, so transparent * fU PT , p W{ , Q ^.-.f cnTno cr >nm'nl 
that the internal organs can be tnere Was not SOine Special 

made out without dissection. For mechanism to retain them. 

The mechanism is of somewhat 

complex nature, and consists of two parts. To understand 
their position we must first determine the orientation of the 
body. We have noticed already the little nerve mass lying 
between the apertures; now development shows that this 
lies on the dorsal surface, and therefore that the short 
region between the apertures corresponds to the back of a 
fish, while the opposite edge is the equivalent of the ventral 
or under surface of the fish. Along the ventral surface of 
the branchial sac, then, lies a groove, the endostyle ; while 
dorsally there is in Ciona a series of processes called 
languets. The grooved endostyle secretes sticky mucus, 
in which the food particles are entangled, and they are 
then swept backwards apparently by the aid of the languets 
into a slit-like opening at the posterior end of the branchial 
sac. This opens into the stomach (st\ the stomach into a 


coiled intestine (in), this into a rectum (r), which runs 
forward to end within the lip of the atrial opening. 

This description may sound a little complicated, but with 
the help of the diagram there should he no difficulty in 
following it. Let us summarise the salient points. A sea- 
squirt may be compared to what chemists call a two-necked 
flask, or, as the more familiar object, to a narrow-mouthed 
coffee-pot. Within the mouth of the coffee-pot let us 
suspend a muslin bag, which may represent the branchial 
sac. At the bottom of the muslin bag let us make a slit, 
and fasten to the outer side of the slit a U-shaped tube, 
so that one of the arms of the U reaches up to the spout, 
and its base to the bottom of the jug. "We have then a 
pretty close model of* a sea-squirt, but to complete the 
resemblance we must suppose that the muslin is covered 
with fine hairs, which continually bale the water through 
its holes. Now pour in water containing coffee-grounds, 
and we find that owing to the hairs (cilia) on the walls of 
the bag, a current is created which drives the water through 
the bag, and ultimately out by the spout. But owing to the 
arrangement of groove and processes already mentioned the 
coffee-grounds are, on the other hand, swept into the slit 
and so into the U tube. 

The muslin bag is the branchial sac, the mouth of the 
coffee-pot corresponds to the mouth of the sea-squirt, the 
U tube to the alimentary canal, the spout to the atrial 
opening. The water, which is swept through the muslin 
bag to ultimately gush out at the spout, is the water which 
is used in respiration, for as it passes through the slits it 
washes the blood contained on their walls, and so purifies 
the blood. The coffee-grounds correspond to the food par- 
ticles which are sifted out from the water, and pass from 
branchial sac to stomach. Here they are digested, while 
the indigestible residue passes into the rectum, and so to 
the lip of the atrial opening. The matter is of course not 
quite so simple as this analogy would suggest, especially in 
that in most Tunicates the branchial sac is so large that it 
has, as it were, squeezed the alimentary canal to one side, 
and the relation of the parts becomes in consequence some- 
what complicated. But the coffee-pot model indicates the 
gist of the matter. 


One interesting point is that, as the description shows, 
the branchial sac has a double function, being both respira- 
tory and nutritive, and that through it there constantly 
flows a food- and oxygen-bearing current. This fact is 
known and appreciated by a little water-flea, or Copepod 
(Notodelphys ascidicola), which takes up its abode within 
the branchial sac of various sea-squirts. It is hardly a 
parasite, for it does not seem to injure the sea-squirt, but 
seeks and obtains shelter, as well as abundant oxygen and 
food from the incoming current. The habit might be de- 
scribed as a first essay towards the adoption of the parasitic 
mode of life, for it is probable enough that many parasites 
began by merely seeking shelter. Such a method of life is 
not peculiar to Copepods, for there are also fish which 
similarly seek shelter within the cavities of sea-anemones 
and sea-cucumbers, and the interesting case of the crab 
and the mussel has been already noticed (p. 202). In all 
such cases the cavity used for shelter must be one in which 
there is an abundant supply of sea-water periodically re- 
newed, by means of which the messmate can both breathe 
and feed. 

A considerable number of simple sea-squirts as opposed 
to those forms which produce colonies are to be found on 
the shore rocks, so that we can pick out one or two only. 
Perhaps the commonest in most places is the " gooseberry " 
sea-squirt (Styelopsis grossularia), to be found on rock 
surfaces as a little bright red body, often so covered with 
mud that nothing but the two bright red orifices is to be 
seen. When touched these disappear in the surrounding 
mud after squirting out a sudden jet of water. With a 
little care it is possible to remove a few specimens without 
injury, and make out something of the internal anatomy. 
It will be found that the body is nearly spherical, and the 
two apertures are placed close together, and are both four- 
lobed. If with a pair of scissors you clip the animal in 
two, you will see that the branchial sac has one deep fold 
in it, as well as some other indistinct ones, and that the 
inner surface of the body-wall has, on its surface, little 
scattered masses ("polycarps"), which are the reproductive 
organs, and are confined to the right side of the body-wall. 
These points are worthy of notice, because they serve as 



FIG. 84. Polycarpa rustica, a common 

distinctions from Polycarpa rustica, another common red 
Ascidian, which has four folds in the branchial sac at each 
side, and has reproductive 
organs on both sides of 
the body-wall. 

The " gooseberry " is 
very common, and from 
its tough, leathery coat it 
is easy to cut into sec- 
tions, which show the 
anatomy clearly. By 
taking a pair of scissors, 
and clipping a few speci- 
mens up at different angles 
and in various planes, the 
structure can be more 
readily understood than 
by even a very careful dissection of a soft form like dona. 
As to the humanitarian aspect of the matter, it is difficult 
to think that one can have more scruples than about slicing 
a cabbage, but a tender conscience may be appeased by 
immersing the specimens for a short time in methylated 
spirit, and this will also assist the subsequent examination 
by hardening the tissues. 

Besides dona intestinalis, which we have already described, 
several species of the genus Ascidiella are common on the 
rocks. It is hardly possible to describe the specific characters 
without going into details which are a little beyond our 
reach, but we may note that a form called A. virginea is 
very abundant in the Firth of Forth, where it grows 
socially in dense masses attached to seaweed, or Polyzoa, 
and is cast on the beach after every storm. It has a 
delicate, transparent test, and the body-wall is often 
beautifully necked with scarlet. If specimens are collected 
immediately after a storm, they will be found to be still 
alive, and the smallest of the bunch will show the beating 
of the heart and the movements of the currents in a very 
interesting way. Sea-squirts from deep water often have 
very delicate tests, so that the internal structure shines 
through clearly, but those found on the shore have usually 
tough, resistant coats, which conceal the underlying organs. 


In addition to the simple sea-squirts there are a great 
number of colonial forms, in which the small individuals 
are embedded in a common test, a number being usually 
grouped round a common atrial opening. Very abundant 
are the species of Botryllus, in which the colony spreads as 
a great sheet of jelly over stones, the surface being studded 
by little stars with a central hole. Each star is a cluster of 
individuals grouped about the common atrial opening, while 
the test of the simple Ascidian is represented by the sheet 
of jelly in which the individuals are placed, and which 
connects the clusters together. The colonies, for the most 
part, avoid the light, and are to be found beneath stones, 
and under overhanging rocks, but they are usually bright in 
colour purple, greenish, yellow, and red tints being common. 

Along with Botryllus the species of Botrylloides also 
occur, in which, instead of being in stars, the individuals 
are arranged in long, double rows, which branch and 
anastomose in a complicated fashion. The colonies form 
their incrustations on the rocks just as Botryllus does, 
and occur in similar localities. Where representatives of 
these two genera occur freely, there will probably also be 
representatives of other genera of compound Tunicates, 
which in some cases, instead of being flat, form little 
stalked masses of jelly. They can always be recognised as 
Tunicates by the occurrence of the individuals, or zooids, 
embedded in a common jelly, and in many cases it is easy 
to pick out a zooid on a needle, and with a lens demonstrate 
the existence of all the parts which we discovered in the 
simple sea-squirt. But though the Tunicates compound or 
simple are an interesting group, we must not linger over 
them, for, generally speaking, they are too difficult as 
regards their minute structure for most amateurs, and the 
distinctions between even the genera rest, in most cases, on 
minute points. 

Finally, we come to the Fishes, of which we can name 
only a few of those which haunt the rocks at low water. 
Everyone who has watched fish in their natural surroundings 
must have been struck with their singular beauty and grace; 
cold, slimy, and shapeless as they seem when dead, in life 
they are full of energy and vitality, as beautifully adapted 


to their surroundings as bird in air or mammal on land. 
Into the details of structure we cannot go, but almost any 
shore fish will serve to give you a general idea of the general 
characters of a fish. 

In the first place, with the exception of skate or dog-fish, 
occasionally thrown up after storms, all our common fish 
belong to the bony fish, or Teleosteans, which are geologically 
recent animals, and display the fish-like characters in their 
highest degree of development. But as the fish in its 
highest development is, above all things, an animal adapted 
for life in mid-ocean, for swift movement, we must expect 
the forms available on the rocks to display the piscine 
characters in a less typical form than their brethren of the 
open sea. The fish which are always to be found in the 
rock pools are those which are specially adapted for that 
life, and which would be as helpless in the open sea as the 
strong swimmers of that open sea would be if confined in 
such pools by any untoward circumstance. Such shore fish, 
therefore, display various peculiarities of form which 
distinguish them from the more typical fish of the open sea, 
but these peculiarities are usually of the kind known as 
adaptive that is to say, they occur in different fish not as 
the result of inheritance from a common ancestor, but as an 
adaptation to a common environment. Thus shore fishes 
are often without scales, they often have an eel-like body 
adapted for creeping through rock crevices, they may be 
flattened to enable them to pass their lives on the bottom, 
and so on. 

Before proceeding to describe the peculiarities in detail, 
let us look at a typical fish, choosing a member of the great 
cod family, which includes many important food fishes. If 
you idly row about in a boat in the summer time not far 
from shore, or watch the streams of sea-water which ebb 
and flow through the deep channels of the rocks, or gaze 
down into the water from a pier or landing-stage, you are 
certain at some time to see shoals of fish of a beautiful 
greenish tint, which dart and wheel and turn in the water 
like swallows in the air, showing gleams of glistening silver 
at every movement. So abundant and so fearless are they 
that even the simple artifice of a bent pin and a piece of 
mussel will often produce several specimens, when employed 


off the edge of the rocks with an incoming tide. The 
humanitarian may protest against this, and exclaim that the 
naturalist cannot admire without seeking to destroy, but the 
fact remains that while you call these fish merely " fish " in 
the indefinite sense, you will observe but little of their 
habits; while if you possess yourself of a few specimens, 
learn their name, and something of their characters, the 
next time you see those shoals you will not only observe 
much more than you did the first time, but your interest 
will be greatly intensified, and your chances of seeing much 

There need be no difficulty as to name, for these pretty 
fish are saithe, or coal-fish (see Fig. 85), in the adult stage 

Fio. 85. Saithe, or coal-fish (Gadus wrens), to show typical fish-like shape, 
di, d 2 , d'J, the three dorsal fins ; v, the ventral fin of right side ; p, the right 
pectoral ; a 1 , a 2 , the two anal fins ; t, the equally lobed tail fin ; b, the rudi- 
mentary barbule. Note also the lateral line, and the operculum (o) covering the 
gills. After Day. 

often sold to innocent housewives as cod, and in the young 
stage known to all boys as poddlers, or by a dozen other 
names beside. The adults grow to a length of two or three 
feet or more, but the shoals found off the rocks in summer 
time are usually the young, and are not more than a few 
inches in length. 

As in most fish, the body is spindle-shaped, tapering 
behind so as to offer the least resistance to the water. It 
ends in a tail fin which is equally lobed, so that every stroke 
drives the animal straight through the water. This is a 
point of some interest, for it is only modern fish which 
possess tails of this kind. In the fish found as fossils in 
the older rocks, as well as in the living dog-fish and skate, 


the tail fin is unequally lobed, the upper lobe being larger 
than the lower. The result of this arrangement is that at 
each stroke the body is inclined downwards, for the larger 
lobe naturally gives greater impetus than the smaller. The 
reason for this is that those fish which have unequally lobed 
tails have their mouths on the under surface, and are usually 
ground feeders, so that each stroke drives them nearer their 
food, which they reach from above. Fishes with equally 
lobed tails, on the other hand, have terminal mouths, are 
swifter and more highly specialised. It should also be 
noted that in fish the tail is the main organ of propulsion, a 
fact which has resulted in various modifications of the body. 
One of the most interesting of these is that the internal 
organs have been shifted forwards, so as to leave the tail a 
mere mass of solid muscle. It is a familiar fact that the 
posterior opening of the food canal in a fish is far forward, and 
that the body organs, heart, alimentary organs, reproductive 
organs, etc., are, roughly speaking, crowded into the small 
space in front of this opening. On the other hand, in most 
vertebrates, such as frog, bird, mammal, the viscera extend 
to the posterior end of the body, and the limbs are the great 
means of propulsion. The student will find it of much 
interest to compare the conditions in prawn or lobster with 
those obtaining in a typical fish. In both cases the tail is 
used as an organ of propulsion, and in both cases is in conse- 
quence converted into an almost solid mass of muscle, which 
renders both sought after by man as food. There are, how- 
ever, many interesting differences in detail in the mechanism 
in the two cases, and some even more interesting resem- 
blances. Thus, in both cases the kidneys are shifted far 
forward into the head region. It must not, of course, be 
supposed that there is any relation between lobster and fish, 
even if the former is legally a " fish," but the two have both 
solved a mechanical problem after a similar fashion. 

While swimming is effected in a fish by means of the 
tail, the necessary steering is accomplished by means of 
the fins. Of these there are two kinds the paired fins 
corresponding to the limbs of other vertebrates; and the 
unpaired fins, which are to be found in the middle axis of 
the body, and vary much in different fish. It is especially 
interesting to note the position of the paired fins. As they 


correspond to the fore and hind limbs of a terrestrial ver- 
tebrate, one would naturally expect that the pectoral pair, 
which are equivalent to the fore limbs, should lie in front 
of the pelvic pair. This is the case in many fish, but in 
the cod family they have been shunted forward till they 
actually lie in front of the pectorals (see Fig. 85). This 
shifting seems to be associated with the general moving 
forwards of the organs of which we have already spoken. 
As regards the unpaired fins we have in the saithe three 
dorsals on the back, and two anals on the ventral surface 
behind the anus, in addition to the tail fin of which we 
have already spoken. 

In regard to the other characters, the gills are of special 
importance. In a living fish there will be noticed a flat 
plate, or operculum, behind the mouth on either side, which 
is constantly opening and shutting. It is easy to observe 
that water is constantly entering by the open mouth, and 
leaving by the opening at the side of the throat which is 
disclosed when the operculum is raised. A more careful 
examination will show that internally the sides of the 
mouth are perforated (usually) by five clefts, bounded by 
bony arches bearing red gill-filaments. Externally these 
openings are not obvious, as they are covered by the 
operculum, beneath whose posterior margin the water taken 
in by the mouth escapes. As the water passes out it purifies 
the blood contained in the gills, so that the mouth-cavity, 
or pharynx, of the fish, like the pharynx of a Tunicate, has 
a respiratory function, as well as its nutritive one. Other 
important peculiarities are the teeth, not confined to the 
margin of the jaws, but also found on the walls of the 
mouth-cavity, and the "lateral line" a series of superficial 
sense-organs which run down the sides of the body, forming 
a conspicuous black line in the haddock, a pale one in the 
saithe. The scales should of course also be noticed, and 
the flat, lidless eyes, so arranged as not to interfere with the 
general curve of the body, and so offer no resistance to the 
passage through the water. Into the anatomical details of 
structure we cannot go, but the external form and the move- 
ments are worth careful study, and your appreciation of the 
graceful movements will probably increase as you learn more 
of the mechanical adaptations which render them possible. 


Before leaving the saithe, we may note that the most 
inexperienced housewife can distinguish it at a glance from 
the cod, by the fact that while the latter has a long process, 
or barbule, beneath the chin, the saithe has the merest trace 
of one (see Fig. 85, b). There are other striking differences, 
but this is the most readily observed, and is worth note, 
because if cod is not a particularly attractive article of diet, 
a full-grown saithe is very much less so. 

Having gathered some general idea of the characters of 
fishes from an examination of the saithe or one of its 
relatives, such as the cod, haddock, or whiting, we may 
glance at the characters of some of the common rock- 
haunting forms. 

Wherever the pools contain weed and stones one may be 
sure of finding at least one species of Coitus, little fish 

FIG. 86.- Sea-scorpion, or bullhead (Coitus scorpius). After Day. 

belonging to the same family as the gurnet, and much feared 
by children on account of their spines and a tradition that 
they are capable of stinging. Two species are common, the 
sea-scorpion (see Fig. 86) and the father-lasher, or lucky 
proach, the former being usually from about six inches to a 
foot in length, and the latter usually only a few inches, 
though it has been found to attain a length of a foot or 
more. In both cases the head is broad and large, curiously 
disproportionate to the narrow, tapering body, and bears a 
very wide mouth, always eager for food. The head is 
flattened above, so that the eyes are in its upper surface 
instead of the sides, as in the saithe, and the margin of this 
flat head is furnished with spines borne on a plate called the 
preoperculum. In addition to these, other spines ornament 
other parts of the body, especially the head, but the skin is 
otherwise soft and scaleless. The gill-cover seems at first 


sight to be very different from that of the saithe, and is apt 
to be a little puzzling. If the saithe be carefully examined, 
it will be seen that the operculum consists of a flat hard 
plate, fringed at the edge with a soft membrane supported 
by some inconspicuous rays of cartilage, the whole lying 
close to the lateral body-wall. In Coitus, on the other hand, 
the soft membrane is greatly expanded, and is supported by 
a number of long distinct rays, curved so as to leave a con- 
siderable space between them and the underlying gills. If 
you seize a living Coitus, you will find that it is capable of 
greatly increasing this space by raising these rays and their 
membrane (the branchiostegal or gill-cover membrane), so as 
to greatly increase the width of the head. As the head 
swells the spines are erected, so as to make the Coitus an 
ugly mouthful. There can be no doubt that this must 
protect the fish against attack, for there are not a few stories 
of birds found choked by getting the distended head with 
its sharp spines fixed in the throat. If you compare the 
ugly "bullhead" with the saithe, you will notice at once 
how much the misshapen head takes off from the graceful 
fish shape, as it must also diminish the swiftness of motion, 
but great swiftness is probably not necessary to a rock- 
haunting form, and the shape fits it for a life among rocks 
and weed. 

As to the other characters, we may notice that the 
pectoral fins are large and fan-like, accentuating the size of 
the anterior region of the body, while the ventrals are small 
and inconspicuous. There are two dorsals and one anal fin, 
and the tail fin is simply rounded and not cleft. There is 
no marked distinction in colour between the two forms, the 
general tint in both cases being brown or greyish green, 
prettily marked and banded with dark brown or black. In 
the sea-scorpion the under surface is pale, or sometimes 
yellow, with strong dark markings. There is no great diffi- 
culty in distinguishing the two species. In Coitus scorpius, 
the larger, the preoperculum bears two spines, the upper 
and longer of which is less than the diameter of the eyes; 
the first dorsal fin has nine to ten rays, the second thirteen 
to fourteen, and the anal nine to thirteen. In Coitus bulalis 
the preoperculum bears four spines, of which the uppermost 
and longest is longer than the diameter of the eyes, and the 


fin rays number as follows: first dorsal, eight; second dorsal, 
eleven to twelve; anal, nine. Both species often occur in 
the same locality, are easily caught, and, in the case of small 
specimens at least, live well in confinement. Very small 
father-lashers can easily be kept alive in a shallow pie-dish, 
provided they are regularly fed, for they are exceedingly 
voracious. Almost any small marine animal is acceptable, 
especially the young of other fishes, which are eagerly 
snapped up. In consequence of their voracity, and the 
ungraceful shape, the bullheads have come in for not a 
little abuse at the hands of even naturalists, who should be 
unprejudiced persons ; but, nevertheless, in life in their 
natural environment, they certainly do not lack that adapta- 
tion to their surroundings which is the first canon of 
beauty, while their vivacity and activity make them most 
interesting pets. 

The next fish we shall consider haunts in life sandy 
places, but is often cast up on the shore, and has such a 
mass of fact and fancy interwoven with it that we cannot 
pass it by. This is the fishing-frog, or "angler" (Lopliius 
piscatorius), sometimes called the sea-devil. It grows to 
a huge size (six to seven feet), and is then certainly ugly 
enough, but very small specimens are fascinating little 
creatures. The head is exceedingly broad and flattened, 
the mouth being enormously wide and capacious. The 
name is derived from the fact that the first dorsal fin is 
represented by a series of spines, of which the first three 
are detached and form the " fishing-lines." The first bears 
a little glistening flap of skin which acts as a lure in the 
following way. The angler partially buries itself in the 
sand ; the filament, which lies close above the mouth, pro- 
trudes from the sand, and its terminal plate, which can be 
moved by an elaborate series of muscles, quivers in the 
water. The result is that little fishes swim up, from curi- 
osity or hope of food ; then the great jaws open and the 
little fishes are seen no more. The stratagem is evidently 
successful, for the anglers obtain an enormous number of 
fishes, so many that in some places the fishermen open 
them for the sake of the contained prey. The anglers 
swim but slowly, so that they could not hope to overtake 
their prey by chasing them. When found thrown up on 


the beach the colours are striking enough, being dark above 
and white below; but it is said that in aquaria the fish 
show remarkable resemblance to the surroundings, and even 
when not buried are very inconspicuous. In the anterior 
regions especially, the sides of the body are furnished with 
fringed filaments, which resemble fragments of weed, and 
must assist the process of concealment. 

Apart from the lure the angler has many striking peculiar- 
ities of form, most of which are obviously adaptations to 
the peculiar habit. Thus, while the pelvic fins are small 
and short, the pectoral are strong and remarkably modified, 
so that the fish can use them to progress over the bottom, 
or to excavate cavities in which the body may be concealed. 
The reason why the arm-like fins are used in creeping along 
the bottom, instead of the same result being produced by 
strokes of the tail as in most fish, is supposed to be that 
the former produces a silent, or rather waveless mode of 
progression, which is more in harmony with the habit of 
stalking the prey than rapid motion accompanied by dis- 
turbance of the water would be. The motion is greatly 
assisted by the somewhat elaborate articulation of the fins, 
which makes great freedom of movement possible. Again, 
the great mouth is furnished with numerous incurved teeth, 
which permit of very free entrance, but no exit. This is 
not always an unalloyed advantage to the angler, however, 
for it has been known to swallow such things as stone 
sinkers, cork buoys, hooked fish, and even the ends of boat- 
hooks or mops, and being unable to readily reject them 
again has been ignominiously captured. But to the tales of 
the power and feats of the angler there are verily no end, 
for its habits have always aroused intense interest from the 
time of Aristotle to the present day. 

It is perhaps hardly necessary to describe in detail the 
other peculiarities of structure, for the huge head, with its 
dangling filaments, makes the animal easy to recognise. Its 
interest is that it illustrates, to an even more striking 
degree than the species of Coitus, how the typical fish-shape 
may be lost as an adaptation to a special mode of life. 

Another interesting fish, sometimes thrown up in hundreds 
on the beach in spring, is Cyclopterus lumpus, the lump- 
sucker, a curious unwieldy animal, interesting on account 


of its habits. The young may be found in abundance in 
the rock pools in summer and autumn, but to get the adults 
one must search in the early spring months. Then, in pools 
through which a stream flows, you may often find a large 
mass of bright pink eggs, adhering to stones or weeds. 
Close beside it, often half uncovered at low tide, is the male 
parent, who with great devotion watches the eggs until they 
hatch. He is said to carry away the young with him after 
hatching has taken place ; but I do not know how to re- 
concile this statement with the fact that the young are 
abundant in the rock pools. Of the devotion of the males, 
however, there can be no doubt, for they may be watched 
every spring, and by marking a specimen it is easy to show 
that the watching lasts for at least several weeks. Un- 
fortunately, as March and April, the months in which the 
eggs are laid, are apt to be stormy months, the weeks of 
watching are not infrequently prematurely cut short by the 
death of the male. In both sexes there is a curious suctorial 
disc on the under side, by means of which the animals can 
attach themselves to any firm surface, but as they are feeble 
swimmers they are unable to resist the action of the waves 
when once torn from their attachment, and the males 
especially, from their prolonged and dangerous proximity to 
the shore, are peculiarly liable to destruction in high winds. 
In regard to the special characters (see Fig. 7) the body 
is short, thickened, and elevated, and marked by strong 
lines of tubercles. Of these there is a prominent row along 
the middle of the back, which, being elevated on a crest, 
gives rise to the Scotch name of paddle-cock or cock-paidle 
(the male), and three pairs of lateral rows, in addition to 
numerous scattered processes. These tubercles, together with 
the ventral sucker (formed of the ventral fins), make it im- 
possible to confuse the fish with any other. The colours, 
especially on the under surface, differ in the two sexes, for 
this is orange-red in the breeding male and bluish black in 
the female. Though its appearance is not appetising, readers 
of The Antiquary will remember that in Jonathan Oldbuck's 
time at least the " cock-paidle " was prized as food. It does 
not appear to be now commonly used in this way, but those 
cast on shore after the storms of spring are said to be some- 
times carted away to be used as manure or for feeding pigs. 


If the adults can hardly be described as graceful, the 
young, on the other hand, are charming little creatures, 
which are readily captured, live well in captivity, and make 
delightful pets. They differ markedly from the adults in 
appearance, being without tubercles, and exhibiting a singu- 
larly close resemblance to tadpoles. This is especially the 
case with specimens taken from dark-coloured pools, for 
these have the dark tint of frog tadpoles. Specimens taken 
from pools containing much bright weed, on the other hand, 
are often a fine green or olive-green tint, with conspicuous 
light streaks behind the eyes. They are active little crea- 
tures, darting about the water much more rapidly than the 
adults, but nevertheless they frequently attach themselves 
by the sucker, and then have a curious habit of tucking the 
tail round the large head. The result, when combined with 

FIG. 87. Common shanny (Blennius pholis). After Day. 

the colour resemblance to the surroundings, is to render 
them very inconspicuous, and it is interesting to watch a 
pool with several of the little creatures darting about, and 
notice how they disappear suddenly from view, to be found 
again after careful search as apparently shapeless masses on 
the weed. Another interesting peculiarity is the fact that 
the tail fin is quite colourless, and therefore practically 
invisible. In consequence the dark - coloured specimens 
particularly seem to be sharply truncated in the posterior 
region, which enhances the peculiarity of the appearance. 

The next fish we shall consider is the shanny (Blennius 
pholis, see Fig. 87), which may be described as a typical shore 
fish, for it lives in shallow pools, lurking under stones and 
weed, and is quite able to withstand the temporary disappear- 
ance of the water. Indeed, in confinement it seems to greatly 
prefer a situation where it can periodically leave the water 
for a time. The colours are not very definite, the body 


being generally greenish, marked and blotched with black, 
but the tints are so arranged as to correspond generally to 
the lights and shadows of a rock pool, and show a very 
considerable range of variation in harmony with changes in 
the surroundings. Specimens may be found of six or more 
inches in length, but a common size is three or four inches. 
Scales are absent as in most shore fishes, and the mouth is 
furnished with strong sharp teeth, quite capable of giving an 
incautious finger a sharp pinch ; their function is to nip off 
the shell-fish, acorn-shells, and so forth on which the 
shanny feeds. In the related wolf-fish (AnarrMchas lupus), 
which is an inhabitant of deeper water, but is often cast 
ashore during storms, the teeth are exceedingly strong, and 
can inflict an ugly wound, but the little blenny can cause no 
apprehension in the case of a discreet person. 

There is little difficulty in recognising so common a fish 
as the shanny, but the following points may be noticed. 
The body is compressed and somewhat elongated, and slimy 
to the touch ; the cleft of the mouth is narrow and strongly 
toothed, and the anterior of the two nasal pits at each side 
is furnished with four or five small filaments. The fins are 
especially characteristic, for instead of two dorsals there is 
one long fin with a very distinct notch near its middle. 
The pectorals are large and expanded, while the ventrals 
are represented by two rays only; there is a long anal 
which, like the dorsal, does not meet the caudal. Nearly 
all these points are shown in the figure. A cunning and 
comical little fish, the shanny is well worth careful study. 
It has a habit of poking its head out of the water or the 
crevice in which it is lying, and as the lips are thick and 
well marked, it has then a ludicrous resemblance to a 
sulky, pouting schoolboy. The pectoral fins are extensively 
used in clambering about the rocks, the small ventrals also 
assisting in this process. It lives well in confinement if 
kept in shallow water and allowed an opportunity of 
leaving the water at times, and is a very favourable subject 
for the demonstration of colour change, as the tints vary 
with those of the surroundings. 

Another very common fish belonging to the same family as 
the shanny is the gunnel, or butter-fish (Gentronotus gunnellus), 
which is, however, in regard to habits at least, a less interesting 


creature. It has a peculiarly elongated and compressed form, 
is exceedingly slimy to the touch, so that though it is not 
particularly difficult to catch it is very difficult to retain when 
caught, slipping through the fingers like the proverbial eel. 
It is most commonly found under stones or weed, often 
quite out of the water, and when uncovered regains the 
water by very vigorous contractions of the body. Apart 
from the eel-like shape, it is readily recognised by a row of 
dark spots, usually about twelve in number, which run 
down the back on or close to the long uniform dorsal fin. 
Otherwise the colouring is not striking. The pectoral fins 
are not large and the ventrals very small, so that there is 
little to break the uniformity of the long, lank body. The 
anal fin is present along about the posterior half of the 
body. In water the gunnel swims easily and rapidly, but 
at low tide it is most frequently found under stones in the 
quiescent state. About six or seven inches is a common 

FIG. 88. Gunnel (Centronotus gunnellus). After Day. 

length, though larger specimens may be found, In early 
summer one sometimes finds the young, curious white 
creatures, with the heart clearly visible through the trans- 
parent body-wall. 

Allied both to the gunnel and the shanny is the vivi- 
parous blenny, a comparatively large fish it reaches a length 
of two feet common between tide-marks. It is a little 
apt to be confused with the shanny, although when the two 
are put together the differences are well marked. As its 
name indicates, the viviparous blenny (Zoarces viviparus) 
gives birth to living young, instead of laying eggs, as the vast 
majority of fishes do. The young are from one to one and a 
half inches in length at birth, and are to be found in various 
stages of growth at all seasons in the rock pools, while the 
full-grown adults only occur there at times. Perhaps the 
most obvious distinction from either the shanny or the 
gunnel lies in the fact that the viviparous blenny has no 
apparent tail fin, the dorsal and anal fins merely meeting at 


the tapering posterior end of the body. The tails of the 
three forms are indeed worth careful comparison, for in the 
shanny the tail fin is distinctly separated from the anal and 
dorsal, in the gunnel these meet it, but the tail fin persists 
unaltered ; a similar arrangement obtains in the young vivi- 
parous blenny, but as it grows older the tail fin disappears, 
leaving only the united dorsal and anal. In general shape 
the viviparous blenny may almost be said to be intermediate 
between the shanny and the gunnel, for it is less elongated 
and compressed than the latter, and more so than the former. 
The long dorsal fin, instead of having a notch as in the 
shanny, has near the tail a region containing ten spines, 
whose height is considerably less than that of the soft rays 
which support the rest of the fin. The result is to produce 
what is known as a "depressed" region in the fin, a very 
characteristic peculiarity. The anal fin is longer than in 
the gunnel, for it extends through about three-fifths of the 

After the blennies we come to that most interesting 
family, the sticklebacks, which are more or less familiar 
to most people. In rock pools the commonest form is the 
fifteen-spined stickleback (Gasterosteus spinachia), which 
reaches a length of six or seven inches. In spring and 
early summer the pools often swarm with the young, which 
are most charming little creatures, and hardy in confinement, 
while a lucky naturalist may now and again find the nests, 
with the fierce father watching over the precious contents. 
The nests are, however, most usually in spots sheltered from 
violent wave-action. 

There is no difficulty in recognising a specimen of the 
fifteen-spined stickleback, for the long snout and small 
mouth, the fifteen spines which represent the first dorsal 
fin, the row of strong plates at each side of the body, and 
the expanded fan-like anal, second dorsal and caudal fins, 
are all eminently characteristic structures. There is also 
something so peculiar about the way in which the little fish 
roots about with its long snout, and directs its tapering 
body in and out of the rock crevices, that one recognises it 
at once as different from the bullheads or blennies the 
other common rock fishes. Like the other sticklebacks, it 
is an active and pugnacious little fish, though its habits 


have received less attention than the three-spined form. It 
does not appear to extend into fresh water, and is most 
abundant in pools containing much weed and stones, but 
I have also found it in sandy places. It will be noted that 
it is the male which makes the nest, and watches over the 
eggs, just as it is the male lump-sucker which watches over 
the eggs. It is true generally of bony fishes that where 
there is any evidence of parental care, it is the male parent 
which takes on this duty. The same is true of Amphibians 
frogs, toads, newts, and their allies while among 
mammals the care of the young usually falls to the mother 

In addition to the fifteen-spined stickleblack, the three- 
spined form (Gasterosteus acideatus] does occasionally occur 
in rock pools, though typically a fresh-water form. It 
occurs not infrequently in brackish pools just at high-tide 
mark, especially those in the vicinity of fresh-water streams. 
In such pools, also, the nests may at times be found, but 
they are too well known to need further description. The 
three-spined stickleback is hardly so pretty a fish as the 
fifteen-spined form, for it has a more typical fish-like 
shape, without the long snout of the fifteen-spined form, 
and with three, or occasionally three or four, spines on the 
back instead of fifteen. Usually the fish are not more than 
two to three inches in length, but they are excessively 
pugnacious, not only fighting furiously with each other, but 
never hesitating to attack fish much larger than themselves. 
In such combats the strong spines, which they can use very 
effectively, form very powerful weapons, while the strong 
plates at the sides of the body form an efficient defence 
against the attacks of other fish. In the breeding season 
the males especially are of a brilliant orange-red beneath, 
the colours both there and in the other parts of the body 
varying in intensity according to the emotions of the fish, 
being brightest after victory, palest after defeat, or when 
the fish are under the influence of alarm. The tolerance of 
either fresh or salt water is remarkable, especially as there 
is no regular seasonal alternation between the two as in 
salmon or some other fish. The extraordinary variability 
must be associated with the power of changing the environ- 
ment ; but while certain varieties seem to be better adapted 


to life in fresh water and others to life in the sea, the 
capacity for change prevents the fixation of these varieties 
as new species. 

Of the large cod family we have already described one 
member, and cannot devote more space to it or the related 
haddock, whiting, cod, pollack, etc., most of which, as strong 
swimmers, are more or less outside our range, though many 
of them may be caught off the margin of the rocks. 
Leaving them we may pass on to the sand-launces, or sand- 
eels, which may be found in immense numbers near the 
mouths of tidal rivers, in shallow water over a sandy bottom, 
or by digging in the sand. Beautiful silvery creatures they 
are, darting like shadows through the water, or burying 
themselves with swift movements in the sand. Like the 
young saithe, which swim in similar shoals, they are eagerly 
attacked by sea-gulls, as well as by predaceous fish and 
porpoises. On the calm summer days when the water is 
so still that thistle-down, blown from the neighbouring 
dunes, floats on its surface, and so clear that the bottom 
seems within the reach of the hand, on such days one 
often sees flocks of screaming sea-gulls circling over dis- 
coloured patches in the water, and ever and again darting 
downwards to emerge with a silvery fish from the dense 
shoals in the water. In the same way the gulls collect 
about the river mouth as the tide ebbs, and seize the little 
fish as they swim in the shallows. That this fate may not 
overtake all, nature has furnished them with a protruding 
lower jaw, which forms an efficient shovel, by means of 
which the little fish may bury themselves deeply in the 
sand. In some places the sand-eels are caught in large 
numbers for bait and food by raking with hooks or rakes 
the loose sand in which they live ; sometimes they are 
merely dug for like sand-worms, but, as all boys know, they 
may also be caught in a fine shrimping-net, or even by hook 
and line. 

There are two common sand-eels, the greater (Ammodytes 
lanceolatus) and the lesser (A. tobianus, see Fig. 2), the 
latter being perhaps the commoner of the two. A little 
care is required to distinguish the two at first, but once 
the differences have been accurately noted the task becomes 
easy. As to size, the lesser sand-eel is usually only three 


to four inches in length, the greater about six to seven 
inches; but the former may reach seven inches, the latter 
twelve to thirteen or more. In both cases the colours are 
similar, being greenish above with broad lateral silvery 
bands and a pale under surface, but the silvery gleam is 
more pronounced in the smaller fish. Further, the latter 
in proportion to its length is more slender than the larger 
form, and tapers more rapidly in the anterior region. When 
once appreciated this is the point most useful in distinguish- 
ing the two, but till this can be done the distinction may be 
very readily made in the following way. Draw an imaginary 
vertical line from the anterior extremity of the dorsal fin to 
the ventral surface ; in the lesser sand-eel this line will cross 
the backwardly-directed pectoral fin, which is elongated and 
pointed; in the greater sand-eel the line passes behind the 
pectoral fin, which is short and rounded. In both species 
note that there is only one dorsal and one anal fin, that 
ventrals are absent, the scales minute, and the whole form 
such as to render the action of burrowing rapid and easy. 
The active agent in the process, as already noted, is the pro- 
truding lower jaw, which is proportionately somewhat longer 
in the greater than in the lesser sand-eel. 

This short list includes most of the fish common in the 
rock pools on the North-east Coast, but to the list may be 
added the flounder, as an example of the exceedingly inter- 
esting family of flat-fish, which includes in the turbot, brill, 
plaice, sole, and others, some of our most esteemed food- 
fishes. Young flounders are usually common in the rock 
pools, and their many peculiarities of structure render them 
worthy of careful study. As is obvious from their shape 
they are ground forms, adapted for life on the bottom. In 
this respect they resemble the skate and the fishing-frog, but 
differ from both in the way in which the adaptation is 
produced. In fishing-frog and skate the surface upon which 
the animals rest is the under surface a condition which 
one would regard as the natural one; but in the flat-fish it is 
one of the sides. In other words, the fish are laterally 
compressed squeezed, as it were, until the upper and lower 
surfaces have become sharp edges. Note the results of this. 
The pectoral fins in an ordinary fish lie at the sides of the 
body, therefore in the flounder we find one on the upper 


coloured surface and one on the lower white surface; the 
pelvic fins in an ordinary fish lie on the ventral (under) 
surface of the body, therefore in the flounder we find them 
both close together on that sharp edge which structurally, 
though not actually, is the under surface of the fish. So 
far all is relatively simple, but one naturally asks, What of 
the eyes'? It is obvious that if they were to occupy the 
normal position we should get one on the upper pigmented 
surface, and one on the lower colourless surface, where, 
owing to the ground habitat, it would be useless. In point 
of fact, both eyes occur on the surface which is normally 
uppermost, but this is accomplished by one of the most 
remarkable phenomena in the development of fishes, the 
gradual migration of the originally lower eye to the pig- 
mented surface. The migration occurs during the early life 
of the flounder, when the bones of the head are soft, and 
results in an extraordinary distortion of the skull. Skulls 
of some of the flat-fish may often be found on the shore, 
and should be studied with special reference to the position 
of the orbits. Similarly, while the young flounder has 
pigment on both surfaces, later the under surface (left side) 
becomes colourless, and the pigment is concentrated on the 
upper surface (right side). 

In some ways one of the most interesting points about 
the flat-fish is the approach they make to a new type of 
symmetry. It is obvious that fish, like so many animals, 
are bilaterally symmetrical that is, the two sides are similar 
to each other mirror images of one another. But in flat- 
fish this similarity is no longer obvious, and the animals 
tend to take on a type of symmetry in which the ventral 
and dorsal surfaces resemble one another. Thus while in 
most fish the ventral fin differs in appearance from the 
dorsal, in the flat-fish it tends to be closely similar. Space 
does not, however, permit of a detailed account of the 
peculiarities of the flat-fish, or a discussion of the many 
interesting points connected with them, and the disputes 
to which they have given rise. 

Small flounders are common in sandy pools, especially 
about the mouths of rivers. They may be distinguished 
from young plaice by the fact that the scales are rudimentary, 
and that there is a row of tubercles at the bases of the 


dorsal and ventral fins. The colour of the upper surface is 
remarkably like that of the sand and mud in which the fish 
live, whereas in the plaice it is blotched with orange spots 
on a brown ground; but the most obvious distinction 
between the young lies in the fact that the plaice has 
well-developed scales and the flounder only rudimentary 
ones. As is well known, the flounder usually lies buried 
in the sand, with only the mouth and protruding eyes 
exposed. It is very voracious and will eat almost any kind 
of animal food. Under the name of "flatties" flounders 
are often captured by boys, either by spearing or by the 
more primitive method of covering them with the bare feet 
as they lie in the shallow sandy water. 

There are a considerable number of flounder-like forms, 
all members of the genus Pleuronectes, which are apt to be 
confused in common parlance; the name "dab" in itself and 
its compounds being loosely applied to several species. It 
is well, therefore, to expend a few pence in obtaining good- 
sized specimens of the flounder (P. flesus), the plaice 
(P. platessa), and the true dab (P. limanda\ so as to learn 
once for all the notable distinctions between them. After- 
wards the recognition of the young will be found easy 




Teleosteans (bony fish, with terminal mouths and equally lobcd or 
rounded tails). 

(1) Some of the fins are at least partially supported by spines. 

.Head spines two, 
shorterthan breadth 
of eye (7. scorpius. 
Head spines four, one 
longer than breadth 
of eye C. bubalis. 

Lophius piscatorius, fish- 

fTwo to four dorsal 
spines G. aculea- 
j tus. 

~ 1 Fifteen dorsal spines 
\ G. spinachia. 

:No tentacle above 
the eye B. pho- 

fNine to thirteen 
JJ black spots on 
|j back (7. gunnel- 

l lus. 

t f Dorsal fin, with de- 
S \ pressed area near 
| ~\ end Z. vivi- 
5 \ parus. 

Body with rows \Cyclopterus lumpus, the 
of tubercles . j lump-sucker. 

(a) Two dorsal fins, 

Head broad and 

the first with 
weak spines. 

. 8 

6 T2 

03 '- 1 

depressed, six 
rays in gill- 

Head armed 

^ r o 

cover mem- 

with spines 


, brane . 

(6) First dorsal" 
represented by 
isolated tenta- 
cles, or spines. 
Pectoral fins 
jointed . .^ 


Head very large, \ 
first tentacle 
with silvery 
lure, two > 
others pre- \ 
sent, mouth J 
very wide .' 

- /^Ventral fins, if 

(c) First dorsal 1 
represented by 
spines, body 
compressed . j 




present, con- 
sist of one 
spine and one 
ray, placed far 
back (abdo- 

& \ minal) . 

f Single dorsal,^ 

divided into 

anterior spin- 

ous and pos- V 

terior soft 

(d) Dorsals occu-^ 
pying nearly the 
whole length of 
the back, body 
elongated and 
cylindrical . J 


region ; tail \ 
fin present .' 
Single dorsal, 1 
s p i n o u s ! 
throughout; j 
tail fin present] 

Single dorsal,"! 

no tail fin, \ 

anal and dor- j 

I sal meeting . J 

(e) First dorsal ^j .A ^ 
represented by I Q ^ 
crest, ventral j S 'o 
sucker . . J ^ 



(2) Fins all with soft rays. 
A. Head symmetrical. 

(a) One 'to three 
dorsal fins, ven- 
tral fins beneath 
throat, body 
elongated . 

(b) Single dorsal 
occupying most 
of back,ventrals 
rudimentary or 
absent, single 

Three dorsal- 
fins, two anal s, 
ventrals with 
six rays 

No ventral fins," 
lower jaw 
long, anus far 

B. Head unsymmetrical. 

Flat-fish with both"! 
eyes on one sur- 
face, one long | 
dorsal fin and i 
a similar long 
anal . .J 


Eyes on right^ J 
side, dorsal fin 1 ]| 
begins above j- - 
its eyes, two | 
pectoral fins . J ^ 

Barbule rudimentary, 
lower jaw longer 
than upper, teeth 

. uniform G. virens. 

-Pectoral fin long and 

pointed A. tobi- 

Pectoral fin short and 

rounded A. lanceo- 


Teeth lanceolate and 
compressed, lateral 
line nearly straight, 
scales present P. 

Teeth conical, lateral 
line curved, plates 
at base of fin -rays, 

' no scales P. flcsus. 


The fishes and sea-squirts described in this chapter are for the most 
part those which are widely distributed round British coasts, though 
in regard to fishes especially other species will be found to be common 
in pools on the Western coast. The curious lump-sucker is commoner 
on Scotch than on English coasts. 



What does ''littoral" mean? Characters of the littoral fauna The 
two other marine faunas Subdivisions of the littoral zone Dis- 
tribution of British forms The geographical regions Origin of 
littoral animals Evidence for and against a pelagic origin 
Difficulties of a final decision Relations of littoral to terrestrial 
and fresh-water forms Conclusion. 

WE have now completed our systematic survey of the 
common animals of the shore, and as we began with a 
preliminary study of the conditions of shore life, so it is 
fitting that we should, in conclusion, return to the consider- 
ation of some general points connected with the littoral 
fauna. In the first place, we have not as yet strictly defined 
the meaning of the word " shore," but have used it loosely as 
meaning the area between tide-marks. It is, however, fairly 
obvious that this area is not sharply marked off from the 
area just beyond low-tide mark. Very little experience in 
shore collecting shows that animals which in one area may 
be found freely on the shore rocks, in another region can 
only be found after storms, and thus obviously occupy 
deeper water. We have noticed this with regard to Alcy- 
onium and the beautiful plumose anemone (Actinoloba 
dianthus), but it is true also of a great number of other 
forms, and has in several cases given rise to active contro- 
versies. Some particular authority gives water of a certain 
depth for some animal, and this is quoted by others as a 
final statement, and yet it is quite possible that in other 
localities the same animal may occur in very different 



depths. Indeed, it is well known that certain Echinoderms, 
for instance, have a very wide range in depth. Generally, 
we may say that in most cases depth of water does not in 
itself determine distribution, taking depth in this case as 
including only those comparatively trifling variations which 
occur in the vicinity of the shore, and are to be measured in 
unit fathoms. It may thus be asked, Is there really such a 
thing as littoral fauna at all, or do the familiar forms of 
the coast go down into the great depths 1 Before we answer 
this question, suppose we in imagination begin a series of 
dredgings off a rich coast, beginning operations quite near 
the shore in water of eight to ten fathoms, and sailing straight 
outwards. In our first hauls it is probable that we would 
get no form which was not already more or less familiar on 
the rocks. We would miss such shallow-water animals as 
the periwinkles and the shore crab, but we should probably 
get plenty of sea-urchins and starfish, various spider-crabs, 
hermit-crabs, Galathea and swimming-crabs, sea-firs, and so 
on, all animals which we know already on the rocks, though 
the species might be different. As we progressed outwards 
not a few familiar forms would disappear, and others would 
appear, but it is nevertheless true that we might take a 
series of dredgings from the East Coast of Scotland across 
the North Sea to the coast of Denmark, without ever 
losing sight of some characteristic littoral forms, especially 
certain Echinoderms. Further, in the course of our journey 
we should nowhere find a depth exceeding fifty fathoms. 
From these observations then we should conclude that the 
littoral fauna must at least extend down to fifty fathoms, 
though, except some of the Echinoderms, there are not very 
many species which can live equally well in water of a few 
fathoms depth and that of fifty or more. 

If, on the other hand, we took our series of dredgings 
on the West Coast of Scotland, we should find somewhat 
different conditions. In the first place we should get into 
deep water more quickly, and in our journey westward 
would soon cross the fifty-fathom line. If we went onwards 
we should find the percentage of familiar species and 
familiar genera decreasing as we approached the hundred- 
fathom line. After this the sea-bottom slopes somewhat 
rapidly down to the great depths, to be measured in 



thousands of fathoms, whose inhabitants are usually peculiarly 
modified for their life in the " utter dark." Generally then 
we may say that the British Isles stand on a plateau 
bounded, except at the West, by the fifty-fathom line. 
The animals which live at the sea-bottom within this area 
or up to the hundred-fathom line on the West constitute 
the littoral fauna. This 
littoral fauna is con- 
trasted with the pelagic 
fauna, which includes 
those animals adapted 
not for life on the sea- 
bottom, but for life in 
the open water, and with 
the abyssal fauna, which 
includes the animals 
adapted for life on the 
sea - bottom at great 
depths. Later, we shall 
have something to say 
as to the relations of 
these three faunas ; mean- 
time we may note that 
the littoral zoophytes 
bud off pelagic medu- 
soids, and that most of 
the littoral animals 
(Echinoderms, Crus- 
tacea, Mollusca, etc.) have 
pelagic larvae. Further, 
the fact that the starfish FIG. 
Henricia sanguinolenta, 
common between tide- 
marks, is to be found also at a depth of over 1,000 fathoms, 
shows that the littoral and abyssal faunas are not sharply 
marked off from one another. 

We have thus defined the littoral fauna as including, 
roughly speaking, all the animals which are adapted for 
life on the sea-bottom in water of under 100 fathoms in 
depth. In many parts of our area, however, as a bathy- 
inetrical map will at once show, the greatest available depth 

. "Herring-bone coralline," or Halecium 
halecinum. After Hincks. A common littoral 


within a reasonable distance from the shore is very much 
less than 100 fathoms, and usually not more than thirty to 
fifty fathoms, so that in most places we may say that our 
littoral fauna includes the animals found on the bottom 
in all depths from 0-30 fathoms. Even this is a con- 
siderable range of depth, and it is natural to ask whether 
it is not possible to divide the littoral area into zones ac- 
cording to the depth. Such attempts have frequently 
been made, but we have already emphasised the fact that 
depth is only one of the factors determining distribution, 
and perhaps not the most important factor. Other factors 
are wave-action, temperature, food, the salinity and clear- 
ness of the water, the nature of the bottom, and so on. 
We shall therefore consider certain areas of the littoral 
region as determined by the nature of the bottom rather 
than by depth alone. Thus the bottom may be rocky, a 
condition often well exemplified between tide-marks, where 
the ebb and flow of the tide and the action of the at- 
mosphere split and fissure the rock surfaces, hollowing 
them out in a way which renders them eminently suitable 
as haunts for many animals. The rock surfaces are over- 
grown with luxuriant weeds, green, brown, and red. 
Near low-tide mark one sees the great blades of oar-weed 
(Laminaria) marking the shoreward limit of the Lamin- 
arian zone, which extends downward to a depth of fifteen 
fathoms. On rocky coasts one finds that the dominant 
forms from high-tide mark to the margin of the Lamin- 
arian zone are limpets, periwinkles, tops, dog-whelks, the 
shore crab, many Amphipods and other small Crustacea, the 
hardy smooth anemones, acorn-shells, the common starfish, 
and other hardy forms. In the Laminarian zone itself an 
enormous number of interesting and beautiful creatures 
occur sea-urchins, starfish, brittle-stars, many anemones, 
the delicately tinted sea-slugs, spider-crabs, the edible crab, 
prawns and Mysids, Galathea and porcelain -crabs, many 
Annelids, and so on. Again, if the bottom be of sand or 
mud, instead of rocks, the great oar-weeds are replaced by 
sea-meadows of Zostera, among whose grassy blades the 
sea-hare, the cuttles, and many other interesting Molluscs 
lurk. By digging in the sand or mud one gets all those 
interesting creatures we have already mentioned burrow- 


ing anemones, such as Peacliia ; burrowing Annelids, such^ 
as Arenicola, Nerine, Glycera ; burrowing Echinoderms, 
such as heart-urchins and Synapta ; burrowing Molluscs, 
such as Solen, Mya, Lutraria, and so on. About the fifteen- 
fathom line one comes to beds of clams, among which many 
kinds of animals are to be found. Beyond this depth the 
large seaweeds rapidly disappear, and the sea-bottom usually 
consists of shell-gravel, sand, or mud, each region having 
its peculiar fauna. 

If, as we have supposed throughout this book, your 
observations are limited to those animals which can be 
obtained without a dredge, the regions which concern you 
are the rocks between high- and low- tide marks, the Lami- 
narian zone, whose margin is accessible at low spring tides, 
and the sand or mud flats to be found especially near the 
mouths of rivers. We have named above the commonest 
inhabitants of these regions, but if we study this fauna in 
detail in various parts of the coast we shall find enormous 
variation. On parts of the East Coast the spider-crab 
Hyas araneus is extraordinarily common, on the West 
it is comparatively rare. In the pools on the Devonshire 
coast a pretty little prawn, Hippolyte cranchii, is very 
abundant, but it does not occur on the East. Throughout 
our study of the common animals we have constantly 
encountered similar facts, and frequently emphasised the 
differences between the fauna of the North and East and 
that of the South and West. Those who have interested 
themselves in the distribution of British plants know that 
somewhat similar conditions prevail with regard to them, 
many species being found on the West which are absent 
from the East. In both cases this may be in part ascribed 
to the difference of climate, the Gulf Stream making this 
much milder on the West Coast. In both cases, however, 
the differences cannot be wholly ascribed to differences of 
temperature. It is not very easy to divide the British area 
into geographical regions according to the distribution of 
the marine animals, but the following divisions at least 
serve to illustrate the problems involved. The German 
naturalist Michaelsen divides the European seas into three 
provinces: (1) the Arctic, including the seas north of a 
line drawn from the north corner of Iceland to the Lofoten 


Islands on the coast of Norway ; (2) the Boreal, including 
the seas bounded on the north by the line just given, and 
on the south by a line drawn above the South Coast of 
England ; (3) the Lusitanian, including the English Channel, 
the Bay of Biscay, the coasts of Spain, and the Mediter- 
ranean. Thus, except the South Coast, the whole British 
area is within the Boreal region; but a map of the ocean 
currents will show that certain of these sweep our western 
shores, and crossing by the Shetland Isles sweep north- 
wards along the coasts of Scandinavia. There is thus a 
constant tendency for the Lusitanian types to travel up 
along the West Coast, and such types may occur in the 
far North in the Shetland Islands, and again on the coast 
of Norway, while totally failing to establish themselves 
on the East Coast. Again, as there is no sharp line of 
demarcation between Arctic and Boreal regions, the Arctic 
forms tend to spread southwards, and usually find it easier to 
gain a foothold in the colder Eastern waters than in those 
of the Western coast. Thus, except in the extreme South, 
our marine fauna is generally of the Boreal type, but on 
the West there is a strong admixture of Lusitanian types, 
and on the East, especially the North-east, a strong admix- 
ture of Arctic types. Especially curious are the conditions 
in the Shetland Islands, where Arctic and Lusitanian forms 

Further, as our whole area is small and the con- 
ditions fairly uniform, a dominant and successful species, 
whatever its original home, is likely to occur in varying 
numbers in all parts of our area. Thus the Norway lobster 
(Neplirops norvegicus), a typical Northern form, which is 
sufficiently abundant in the Firth of Forth to be the object 
of an important fishery, does also occur, though not in such 
abundance, off the South and West Coasts. The common 
hermit-crab of the Boreal region is Pagurus bernhardus, and 
of the Lusitanian P. prideauxii ; but on the West Coast the 
two occur together in almost equal abundance. Similarly 
the Stenorliynchus of the Lusitanian region is S. longirostris, 
of the Boreal S. phalangium ; but in the Firth of Clyde the 
two occur in almost equal numbers. Perhaps the prettiest 
example of this overlapping process, however, is the dis- 
tribution of the common starfishes. The common starfish, 


Asterias rulens, is the Boreal form, and is replaced in the 
Lusitanian region by the spiny A. glacialis. The latter 
species is totally absent on the East Coast of England 
and Scotland, where A. rubens is abundant, often extra- 
ordinarily abundant. On the West Coast of Scotland 
both species occur, but A. glacialis is not very common. 
In the South-west of England both species are abundant, 
but east of Plymouth A. glacialis disappears. In this 
case the Lusitanian form seems to find it difficult to 
oust the Boreal species even in the warm waters of the 
West. The two forms show no very obvious differences 
of diet. 

It is not possible to discuss in detail the distribution of 
British marine animals, but we may say generally that a 
form which occurs all round our coasts is probably a Boreal 
form; one which is found only on the South and West 
Coasts probably Lusitanian ; one confined to the North and 
North-east probably Arctic. The study of distribution is 
of great interest, and it is not necessary to travel over 
wide areas to study it, for the differences between adjacent 
areas are of as much interest as those between the ex- 
treme North and extreme South, and illustrate the same 

The more attention you devote to problems of distribu- 
tion, the more will you become impressed with the fact 
which we have constantly endeavoured to emphasise, that 
the shore is the region characterised essentially by its great 
variability. If you study one area for a succession of years 
you will notice how currents change, how deposits brought 
down by rivers vary in character and distribution. Closer 
observation is required to show that there are also gradual 
variations in the salinity of the water, its clearness, tem- 
perature, and so on, while the aid of the geologist must be 
invoked to demonstrate the fact that the land is undergoing 
slow oscillations of level, stable and changeless as it may 
seem. Now these constantly changing conditions have a 
most important effect upon the littoral animals, for they 
induce relatively rapid variation. For example, the Firth 
of Forth, from a multitude of causes, grows muddier year 
by year. We know that muddy water is fatal to many 
organisms, owing to its forming a deposit on their delicate 


breathing organs, and so asphyxiating the animals. But the 
danger is so common that many animals notably crabs 
have special means of filtering the water before it finds 
access to the gills. In crabs the filtering arrangement is 
obtained by spines and notches on carapace and claws, or 
by hairs," all structures subject to variation. In the Firth of 
Forth the increasing impurity of the water is certainly 
eliminating certain animals, as it is probably contributing 
to the increase of other mud-loving forms. In the case of 
crabs, for instance, there must be, as it were, a premium on 
the forms best adapted for filtering the water used in 
respiration, for these only can thrive and multiply. The 
result must be to produce relatively rapid variation, for the 
progeny of parents which had both an elaborate filtering 
apparatus will have a better chance of success than the 
progeny of less specialised forms, or of a mixed union. 
Similar variations of physical environment take place every- 
where on the shore area ; as the conditions change and new 
combinations occur, new places in nature are left vacant for 
progressive forms, with the result that the shore area is one 
where life is fast, and evolution rapid it is not the place 
for decadents or survivals. It is probable that this rapid 
evolution has always occurred in the littoral zone, so we 
should expect to find that the genera and species now living 
in the area are modern in type, and may reasonably be 
regarded as having arisen within the area. But where did 
their progenitors come from? Has there always been an 
abundant fauna, or can we go back to a period when the 
shore waters were comparatively empty *? What relation has 
the littoral fauna to the two other great faunas the pelagic 
and the abyssal ? 

The answers to these questions are difficult and debated, 
but it may be worth while to look for a little at the matter, 
even if we cannot hope to reach a definite conclusion. In 
the first place we may clear the way a little by excluding 
the abyssal fauna from consideration. Its members are 
strangely modified animals, which, there is reason to believe, 
have been derived at very different periods from littoral or 
pelagic forms. Apart even from the fact that these deep-sea 
animals display many peculiarities of structure, the physical 
conditions which prevail in the great depths the darkness, 


the absence of plants, and the consequent limitation of the 
food-supply, the low temperature, the high pressure, and so 
on make it very improbable that the most primitive 
animals lived there. The problem before us, therefore, is 
really, Were the primitive animals littoral or pelagic 1 The 
evidence upon which the judgment must be pronounced is 
derived first from the geological history of animals, and 
second from their life-history. 

What does geology teach us as to the origin and 
antiquity of shore animals? The earliest fauna we know 
is that of the Lower Cambrian rocks, and, especially in 
America, numerous fossils have been obtained from these 
beds. The fossils are, generally speaking, littoral in type, 
and they show that even in those far-off days the main 
classes of Invertebrates were distinctly marked off from one 
another ; Coelentera, Echinoderma, Crustacea, Mollusca, were 
represented then as now in the littoral waters, and their 
representatives showed many of the characters of the littoral 
forms of the present day. The presence of these numerous 
littoral animals in these old rocks, coupled with the paucity 
of pelagic forms, may seem to prove decisively the greater 
antiquity of the former; but the apparent strength of the 
argument is diminished by two considerations, In the 
first place, though in those old rocks there are actually 
imprints of jelly-fish, yet generally the animals which are 
abundantly represented as fossils are those only which 
were possessed of hard parts. Now, as we have already 
seen, it is characteristic of shore animals that their hard 
parts are well developed, while pelagic animals have usually 
little in the way of skeleton. The abundance of fossil 
littoral animals, even in very old rocks, may then be due 
to the fact that these are readily fossilised, rather than to 
their abundance relative to pelagic forms. Similarly, in 
the second place, those old rocks were laid down not far 
from land in relatively shallow water, so that littoral 
forms only would be likely to become entombed in sedi- 
ment, and so fossilised. In general, though geology shows 
us that littoral animals are extraordinarily old, it virtually 
tells us nothing as to their age relative to other animals. 

We are thus thrown back upon the evidence derived 
from a study of the life-history of littoral forms, but only 



to find that it is so ambiguous that it is capable of inter- 
pretation in two diametrically opposite ways. It may be 
affirmed that (1) pelagic animals 
have arisen from littoral ones, 
and (2) littoral animals from 
primitive pelagic forms, and both 
positions can be supported by an 
imposing array of arguments. 
Think of the life-histories of the 
littoral animals we have studied : 
In the Coelentera we have often 
an alternation of generations, the 
life-history including a jelly-fish 
stage adapted for a pelagic habi- 
tat, and a fixed zoophyte stage 
adapted for life on the bottom. 
Among the worms there is usually 
a larval pelagic stage ; a little 
top-shaped larva called a trocho- 
sphere occurs in the life-history 
of most of the marine bristle- 
worms, and is to be found near 

the surface of the sea '. swims 
should be contrasted with Fig. 6. by means of the motile threads, 

Note short manubrium and the ! -_i,' v. V* A 

four tentacles. After Hincks. or cilia, which occur in bands 
on the surface of the body, and 

is later, by a process of metamorphosis, converted into the 
more or less sedentary adult. The Echinoderms, again, as 
we have already seen, have larvae very different in character 
from the adults, and adapted for a free swimming and not 
a sedentary existence. We have also emphasised the occur- 
rence of pelagic larvae of many strange shapes among the 
Crustacea, and a tow-netting at almost any season of the 
year will show you that the surface-water simply teems 
with these. The Mollusca also add their quota of minute 
larval forms to the fauna of the open sea. Generally we 
may say that although there are a few exceptions, yet it is 
true of littoral animals as a whole that they produce minute, 
active, pelagic larvae. 

Further, these larvae are usually simple in structure, and 
are often devoid of those peculiarities which are diagnostic 


of the class to which the adult belongs; thus the very 
young mollusc is like a young 
worm, and is without such struc- 
tures as shell, foot, mantle, etc., 
which are characteristic of the 
adults. Adult Echinoderms are 
radially symmetrical, but the 
larvse are bilaterally symmetrical ; 
we might go on to give many 
other examples, but these may 
serve to make the point clear. 
There can be no reasonable doubt 
that in some cases these simple FIG. 91. Naupiius of Peneus, a 
larva, display what has been ff^J^fyyy^ 

aptly called " ancestral remi- Crustacea, and is very common 
niscence"; that is, they display ^the^surface of the sea. After 

ancestral features, which the 

adults have lost. Thus the long tail of the megalopa stage 
of the crab shows that crabs had long-tailed ancestors ; the 
shelled larvse (veligers) of the common sea-slugs show that 
these are descended from ancestors with shells. Can we, 
then, say generally that the occurrence of pelagic larvse in the 
life-history of littoral forms shows that these all had pelagic 
ancestors 1 It would seem that such a view had much plausi- 
bility, and yet there is a good deal to be said against it. 

In the first place, when we study pelagic animals closely, 
we find that while they often appear at first sight to be 
extraordinarily simple and primitive, yet close examination 
shows that they must have had complex and specialised 
ancestors. Thus there are a great number of pelagic 
molluscs, often without shell, sometimes without foot or 
mantle, delicate and transparent in texture, simple, as one 
might say, in structure, and yet closer study shows that 
they are apparently descended from littoral forms with 
distinct shell, foot, and mantle. The same thing happens 
in other groups, and leads us to the conclusion that pelagic 
animals in general are often, apparently as an adaptation to 
their peculiar habitat, simple, delicate, and transparent 
creatures, but this simplicity is adaptive and not primitive. 

If armed with this deduction we return to the pelagic 
larvse of littoral animals, we shall find some reason to doubt 


our first hasty conclusion that these minute transparent 
creatures are really simple really represent the primitive 
pelagic ancestors. The larvae must have means of keeping 
themselves afloat, and these means are often wonderfully 
elaborate; they often have curious spines and processes, 
whose object seems to be to prevent them being engulfed by 
a narrow-mouthed foe, but which are too complicated in 
structure for us to believe that they could occur in a truly 
primitive animal. These are common in Crustacean larvse, 
and well shown in the accompanying figure. Another diffi- 
culty is that in Echinoderms, where the occurrence of simple 
pelagic larvae is so striking a characteristic, the larvse of 
the different classes differ from one another markedly. For 
example, we have seen that morphologically the brittle-stars 

and starfishes are 
nearly related, but 
nevertheless the larvae 
in the two classes 
show marked differences. This at 
once introduces a difficulty in regard 
to ancestry, if we suppose that the 
larvse represent ancestral forms. 

Pro. Oi-Zoea of a crab(TWa . . 

Note the long seems impossible to doubt that while 

the adult starfish and brittle-stars 
have been diverging, the larvse 
have also been diverging along different lines. That is, 
the common ancestors of starfish and brittle-stars must 
have had larvse quite different from the larvse either of 
existing starfish or existing brittle-stars, and if we endeavour 
to discover the characters of those original larvse by studying 
the common characters of starfish larva and brittle-star 
larva, we find that this original larva becomes pretty vague. 
Generally we may say that just as the apparent simplicity 
of pelagic animals when closely studied becomes adaptive 
rather than primitive, so the simplicity of the pelagic larvaa 
of shore animals when closely examined no longer appears 
to be due entirely to " ancestral reminiscence," but acquires 
an adaptive significance. 

This rather subtle argument would perhaps have little 
force against the theory of the pelagic origin of shore 


animals, if we could not give a reason why pelagic larvae 
showing adaptive simplicity should occur in the life-history 
of shore animals. But a twofold reason is fairly obvious, 
and has already been suggested by implication. Shore 
animals usually have armour, are often sedentary, are rarely 
strong or swift swimmers: the minute active larvae ensure 
distribution ; in their own sphere they fulfil the same 
function as the winged seeds of our great forest trees, and 
their occurrence in the life-history is justified by this fact. 
Again, Prof. W. K. Brooks (see his Foundations of Zoology 
for details) suggests that this occurrence is also justified by 
the fact that life on the whole is less precarious in the open 
sea than near the shore. We have repeatedly emphasised 
the fact that in the shore waters there are multitudes of 
sedentary animals who live upon minute creatures found in 
the water, and who are constantly creating miniature whirl- 
pools in the water as they lash it through their bodies. 
Against such maelstroms the young forms would have no 
chance, so that it is safer for them to acquire more and more 
purely pelagic characters, and get out into the open where 
there are not so many hungry mouths ever ready for food. 

We thus see that the arguments for the theory of the 
pelagic origin of littoral animals seem to be nearly balanced 
by the arguments against. Does the converse theory that 
pelagic animals originated from littoral fare any better ? The 
theory may be put in this way. Littoral animals send off 
pelagic larvse out into the open, and the specialisation of 
these larvae takes place along different lines from that of the 
adults ; the larvae acquire elaborate mechanisms to keep 
themselves afloat, forms of armour which may protect them 
without adding greatly to the body-weight, such pale and 
delicate colours as may render them inconspicuous in their 
uniform background, and so on. Is it possible that long ago 
some of these larvae forgot to grow up, if we may put the 
matter so, and gave rise to the original pelagic animals 1 Is 
the resemblance between pelagic animals and the pelagic 
larvae of littoral animals due to the fact that the latter or 
similar forms were long ago the ancestors of the first, in- 
stead of to the converse relation 1 We shall not follow the 
question in further detail perhaps to some it may seem to 
be identical with the momentous question whether the egg 



or owl came first but enough has been said to show that 
the matter is worth thinking about. In closing, it may be 
well to note that while on the one hand there are naturalists 
who believe that the primitive animals were pelagic, and 
on the other those who believe that they were littoral, there 
is also a third and perhaps increasing school who hold that 
while existing pelagic and littoral animals are interlocked 
and interrelated in a thousand different ways, we have no 
data at present from which we can discover 
anything of the characters of the primitive 
forms. Even those, however, who believe 
that the open sea was the first home of life 
do not deny that most of the existing 
pelagic animals have passed through a lit- 
toral phase, and then returned to the open 

In the above discussion we have confined 
ourselves to the evidence derived from In- 
vertebrates, but those who follow the argu- 
ment in larger works should not forget that 
there is also a pelagic fish fauna, a pelagic 
mammalian fauna (whales, dolphins, etc.), 
even a pelagic insect. The last two cases 
show that from land and air, as well as 
FIG. 93. Sea-goose- f r0 m the shore, animals may return to the 

berry, or Pleuro- ... J 

brackia, with the easy life of the open sea. 
ed? ta A peiagfcco?" &itol*l animals are not only interesting 
lenterate with no on account of the question of their rela- 
tion to pelagic forms, for we must think 
also of their relation to the fresh -water and terrestrial 
forms. Many shore animals live near the mouths of rivers 
or streams, and not a few of them learn to tolerate a con- 
siderable admixture of fresh water. By some such process 
of gradual colonisation, we can suppose many fresh-water 
forms to have originated. Periwinkles and some Crustacea 
live at or near high-tide mark, and can tolerate free exposure 
to the atmosphere ; it is reasonable to believe that in this 
way some terrestrial Molluscs and Crustacea may have arisen 
from littoral forms. The shore animals thus constitute a 
most interesting group, and have relations with most of the 
other great faunas of the globe. 


All this may, however, be objected to as somewhat 
speculative, and it may be well to emphasise the practical 
nature of this volume by briefly mentioning, in conclusion, 
some possible lines of work for the shore naturalist. One 
would naturally seek, in the first place, to acquire a general 
knowledge of the common forms, and to obtain such an 
acquaintance with species as to give one a general idea of 
the meaning of specific differences, and ensure accuracy of 
observation the last being a quality of somewhat slow 
growth. When this has been accomplished, the time for 
specialisation begins. Possible lines of work are many. 
For example, there is much to be done in regard to colour, 
even looked at in its most external aspect. The range of 
colour variation, the relation of colour to environment, and 
kindred problems, are still untouched in many groups. 
Most work in this respect has been done in Crustacea, but 
Echinoderms and sea-anemones may be mentioned as suitable 
objects for such investigations. Then the diet of many 
shore animals is still very imperfectly known, and much of 
the evidence points to the conclusion that in many cases the 
food varies with the locality. Where this occurs the relation 
of the diet to local variations in structure is obviously a 
point of much interest. Again, many shore animals are 
undoubtedly very variable, and the nature and extent of 
this variation offers an interesting subject for investigation. 
It seems probable that among the bristle-worms the range of 
variation is very extensive, and that systematic investigation 
would considerably reduce the number of so-called species. 
In regard to the habits of even the commonest forms much 
still remains to be done, and the keeping of isolated animals 
in confinement might yield valuable results in this respect. 

But this book is primarily addressed to the many, rather 
than to the few who can spend much of their time in 
scientific pursuits, so we may perhaps, in conclusion, urge 
the beginner not to allow an interest in form or in 
"problems" to obscure an interest in animals as living 
creatures. It is much to learn to appreciate the charm of 
the crowded shore area, to see the great drama of life which 
unfolds itself there, as in other regions, to the patient ob- 
server, and to realise something of the unity of nature, of 
the order which runs through the apparent chaos of life. 


Books marked thus * are those whose nomenclature has been employed in 
the text. 


(1) A Manual of British Marine Zoology for the British Isles, by 
P. H. Gosse. Two parts. London, 1855. Now out of print, but it 
may occasionally be picked up second hand. In many ways it is a 
most useful book. 

(2) The Marine Invertebrates and Fishes of St. Andrews, by W. C. 
Mclntosh. Edinburgh, 1875. Gives most useful lists, with many 
notes on habits, distribution, and so on. 

(3) The Marine Invertebrate Fauna of the Firth of Forth, by Herdman 
and Leslie. Edinburgh, 1881. A similar work, but not quite so full. 

In addition reference should be made to the works of Gosse, Lewes, 
Woods, and others, most of which are published under general titles. 
Further, the Reports of the different Biological Stations often contain 
important faunal lists, etc. , for their special localities. See especially 
the Journal of the Marine Biological Association, published at Ply- 
mouth, and the Reports of the Liverpool Marine Biology Committee. 

For details of structure reference should be made to the Outlines of 
Zoology, by J. A. Thomson (third edition, Edinburgh and London, 
1899), or to some of the books of reference named in 'it. As a book 
of more elementary character, An Introduction to the Study of Zoology, 
by B. Lindsay (London, 1899), may be mentioned. 


(1) *Bowerbank's Monograph of British Spongiadce (vols. i.-iv., 
1864-82) is the standard work, but it may be supplemented by 

(2) A Revision of Generic Nomenclature and Classification in 
BowerbanTcs British Spongiadce, by R. Hanitsch, in Transactions of 
Liverpool Biological Society, vol. viii., 1894. 


There is no English book dealing with the British representatives 
of the entire group, but certain of the sub-classes have been fully 

A. HYDKOZOA (Sea-firs, etc.). 

(1) * Hincks's British Hydroid Zoophytes. London, 1868. 

(2) Allman's Monograph of GymnoUastic Tubularian Hydroids. Ray 
Society, 1871-2. 



(3) Forbes's Monograph of the British Naked-eyed Medusce. Ray 
Society, 1848. 

(4) For modern terminology reference may be made to E. T. 
Browne's British Hydroids and Medusce in the Proceedings of the 
Zoological Society of London, 1896. 

(5) Ellis's Essay towards a Natural History of Corallines (1755) is a 
carious old book of considerable antiquarian interest. 

(6) Johnston's History of British Zoophytes (Edinburgh, 1838) is 
comprehensive as regards the ground covered, but the descriptions in 
most cases are too vague to be of much use. 


(1) * Gosse's History of the British Sea-anemones and Corals 
(London, 1860) is the standard work on the subject, but for the 
modern names of the British sea-anemones reference should be 
made to 

(2) A Revision of the British Actiniae, by Haddon and Shackelton, 
in Transactions of the Royal Society of Dublin, 1889 and 1891. 

We are unfortunate in not possessing books which deal with the 
British representatives of such forms as the allies of Dead Men's 
Fingers (Alcyonium), Lucenaria, the large jelly-fish, the Ctenophora. 
and so on. Some of these are dealt with in Johnston's British 


(1) The volume called * Worms, Rotifers, and Polyzoa, in the 
Cambridge Natural History (vol. ii., 1896), by various authors, is an 
admirable introduction to the subject, especially as regards the Marine 
Bristle-worms. It contains numerous references which will enable 
those interested to pursue the subject further. 

(2) Mclntosh's British Annelids (Ray Society, 2 vols., 1873 and 
1900) treats in detail of the British species of Nemerteans and certain 
families of Bristle-worms. 

(3) Johnston's British Mu'seum Catalogue of Non-parasitical Worms 
(London, 1865), though not very full, and vague in its descriptions, is 
helpful in some ways. 


(1) The standard work of reference is * Jeffrey Bell's Catalogue of 
British Echinoderms in the British Museum (London, 1892), but it 
will probably be found difficult to use. 

(2) Forbes's British Starfishes (London, 1841), thougnout of date, is 
well worth reading on account of the interest of the style. 


(1) * Bell's History of the British Stalk-eyed Crustacea (London, 1853) 
is the standard work on the higher forms, but it should be sup- 
plemented by 

(2) Stebbing's History of Crustacea. London, 1893. International 
Science Series. 


(3) Norman's British Mysidce, a paper in the Annals and Magazine 
of Natural History (vol. x., 1893), together with some other earlier 
papers in the same Journal, will be found helpful, but their results 
are to a large extent incorporated in Stebbing's volume. 

(4) For certain of the lower forms Bate and Westwood's History of 
the British Sessile-eyed Crustacea (2 vols., London, 1861-8) may be 

(5) White's Popular History of British Crustacea (London, 1857) is 
a useful and comprehensive little book. 


(1) * Forbes and Hanley's History of British Mollusca. 4 vols. 
London, 1853. 

(2) Jeffrey's British Conchology. 3 vols. London, 1863-9. 

(3) Alder and Hancock's Monograph of British Nudibranchiate 
Mollusca. Kay Society, 1845-55. All these works are well illustrated, 
and should be consulted, if only for the plates. There are many 
other works of greater or less extent on the British shell-fish, but 
these may serve for purposes of identification. 

(4) For modern names see Norman's Revision of British Mollusca, in 
Annals and Magazine of Natural History, vols. v. and vi. (1890). 


Although in Prof. Herdman we have an eminent British authority 
on this difficult group, his publications have mostly appeared in 
scientific journals which are not always readily accessible. Brief 
notes on the British species are included in *A Revised Classification 
of the Tunicata, etc., published in the Journal of the Linnean Society, 
vol. xxiii., 1890 ; but this paper will hardly be intelligible to those 
who have not considerable acquaintance with Tunicate anatomy. 
The same author's article on Tunicata, in the Encylopcedia Britannica, 
republished in a volume entitled Zoological Articles (London, 1890), 
affords a valuable introduction to the subject. In Forbes and Hanley's 
Mollusca brief descriptions of the external appearance of some common 
sea-squirts are given. 


(1) Day's Fishes of Great Britain and Ireland. 2 vols. London, 


(1) A paper on Tlie Fauna and Bottom- Deposits near the Thirty- 
Fathom Line, etc., by E. J. Allen, in the Journal of the Marine 
Biological Association (vol. v., 1899), gives a large amount of informa- 
tion on the distribution of British forms, with very copioiis references. 
Many of the works cited above also include distribution. 



Figures in italics refer to illustrations ; those in thick type to the 
pages where technical terms are defined. 

Abdomen of crayfish, 153 
Aberdeen, 193 
Aberystwyth, 35, 265 
Abyssal fauna, 319, 324 
Acontia, or stinging-threads, 66, 


Adaptive characters, 297 
Alnmouth, 35, 81, 265 
Alternation of generations, 17, 64 
Alveolus of Aristotle's lantern, 

Ambulacral areas of sea-urchin, 

1 37 / 38 
Lot t loo 

Ambulacral groove, 127 
Ampullae of sea-urchin, 138 
Anal fins of coal-fish, 298 
Ancestral reminiscence, 327 
Anchors of Synapta, 144 
Annuli, or rings, 61 
Antennae of lobster, 156 
Antennules of lobster, 156 
Anus, or posterior opening of the 
food canal 

of sea-urchin, 137 

of Cucumaria, 143 

of heart-urchin, 141 
Arctic region, 321 
Aristotle's lantern, 135, 136 
Auditory organs of Mysis, 212 
Autotomy, or self-mutilation, 11, 
162 ; of Galathea, 176 

Barbule of cod, 301 

of saithe, 298 
Base of sea-anemone, 65 

Basipodite, 174 

Beaks of mussel shell, 268 

Bilateral symmetry, 143 

Biramose appendages, 161 

Boreal region, 322 

Bournemouth, 35 

Branchial sac of sea-squirt, 292 

Brood pouch of Mysis flexuosa, 


Buccal cavity of Nereis, 87 
Burrowing animals, 7, 321 
Bursse of brittle- star, 130 
Byssus, 270 

of mussel, 267 

Carapace of crayfish, 155 

of crab, 10 

Cardinal teeth of Cyprina, 279 
Carpopodite, 174 
Cephalothorax, 153 
Chelipedes of crayfish, 156, 161 
Chitin of Crustacea, 150 
Cirri of Nereis pelagica, 84, 88 

of parapodia, 86, 95, 109 

of Trochus, 235 
Ccenosarc of Alcyonarians, 75 
Collar of Sabellids, 116 

of Serpula, 117 
Column of sea-anemone, 65 
Commensalism, 187 
Coxopodite, 174 

Dactylopodite, 174 
Disc of Ophiura, 130 
of sea-anemone, 65 




Dorsal fins of coal -fish, 298 
Dunbar, 35 

Egg capsules of dog-periwinkle, 

242 ; of whelk, 243 
Eggs of Cirratulus cirratus, 111 

of Dendronotus, 258 

of Eulalia viridis, 102 

of lobster, 173 

of lumpsucker, 305 

of Mysis, 210 
Elytra, or scales of Polynoe, 94-6 

of Sthenelais, 98 
Epidermis of Cyprina, 279 
Epipodia of sea-hare, 250 
Exhalent aperture of mussel, 267 
Exhalent siphon of Tapes, 268 
Eyes of scallop, 274 
Eye-spots of sea-urchin, 137 

Falmouth, 35 

Firth of Clyde, 35, 165, 276, 322 
Firth of Forth, 20, 63, 81, 111, 
165, 254, 261, 272, 275, 285, 
295, 323, 324 

Flagella of crayfish's antennae, 156 
Foot-jaws of crab, 160 

of crayfish, 156 
of lobster, 160 
Foot of limpet, 24, 226 
of Molluscs, 33 

Genital pits of Aurelia, 77 
Gills of Arenicola, 30 

of Cirratulus cirratus, 111 

of Crustacea, 152 

of Doris, 251, 252 

of edible crab, 160 

of limpet, 226 

of Nerine, 110 

of Nephthys hombcryii, 109 

of Pectinaria, 115 

of Sabellaria, 118 

of Serpula, 117 

of TereMla, 113 
Gill separator, 160 
Gizzard of crayfish, 157 
Gland-shields of Arenicola, 91 

of Terebella, 114 
Gonothecse, 50 

of Campanulai'iaflexuosa, 52 

Gonothecse of sea-firs, 50 

of Plumularia setacca, 57 
of Sertularia pumila, 55 

Head of Phyllodoce lamelligera, 

Heteronereis of Nereis pelagica, 

106 ; of Nereis virens, 107 
Hinge of Tapes, 268 
Hooks of Terebella, 113 
of Sabellids, 116 
Hydroid polypes, 44 

Ilfracombe, 35, 193 

Inhalent siphon of Tapes, 268 

Interambulacral areas of sea- 
urchin, 137, 188 

Introvert of Glyceridse, 108 
of Nephthydidae, 108 
of Nereis pelagica, 87, 104 
of Phyllodoce lamelligera, 100 

Ischiopodite, 174 

Jaws of Glycera capitata, 109 

of Nereis pelagica, 87, 104 
Joppa, 127 

Lateral line of fish, 298, 300 
Ligament of mussel, 268 

of Cyprina islandica, 279 
Littoral fauna, 319; origin of, 

325 et seq. 

Lusitanian region, 322 
Lyme Regis, 35 
Lynmouth, 170, 247 

Madreporite, 126 

of brittle-stars, 131 
of heart-urchin, 142 
of sea-urchin, 137, 138 
of Solaster papposus, 128 

Mandibles of crayfish, 156 

Mantle of limpet, 24, 226 
of bivalves, 227 

Manubrium of medusoid, 17, 40 

Masking of crabs, 14 

Maxillae of crayfish, 156 

Maxillipedes, 156 

of edible crab, 160 
of lobster, 160 

Megalopa of shore crab, 206, 327 



Meropodite, 174 

Mesenteries of sea-anemones, 66 

of Arenicola, 92 
Millport, 35, 81 
Moulting in crabs, 204 
Mouth-papillse of Ophiura, 130, 

131 ; of AmpUura, 133 
Mouth-shields of Ophiura, 130 
Mysis stage of Norway lobster, 


Nauplius of Peneus, 327 
Nematophores of Plumularidse, 57 
Nephridia, or kidney tubes, 29, 

92, 93 

Nerve-cord of Arenicola, 92 
North Berwick, 35 

Operculum of acorn-shell, 220 

of coal-fish, 298, 300 

of crabs, 194 

of sea-firs, 53 

of molluscs, 6, 244 

of Serpula, 117 
Orbits of crab, 160 
Oscula of sponges, 38 

Paignton, 35 

Pallial sinus of Tapes, 268 

Palps of Nereis pelagica, 84, 88, 

104; of Tapes pullastra, 269 
Papillae of Doto, 259 

of Eolis, 260, 261 
of Trophonia, 116 
Paragnaths of Nereis pelagica, 104 
Parapodium, 83, 84 

of Nephthys homier gii, 109 
of Nereis pelagica, S6 
Pectoral fin of coal-fish, 298, 300 
Pedicellarise of Echinoderms, 127, 

Peduncle of crayfish's antenna, 


Pelagic fauna, 2, 319, 325 et seq. 
Pelvic fins of fish, 300 
Pentamerous symmetry of sea- 
urchin, 139 
Penzance, 35, 63 
Peristomium of worms, 84 
of Nereis pelagica, 86 
of Terebella, 112 

Peri visceral fluid of sea-urchin, 

Pharynx of fish, 300 
of Nereis, 87 

Pinnse, or branches of Hydrall- 
mania falcata, 56 

of Plumularia setacea, 57 

Pinnate tentacles of Alcyonium, 

Poly carps of sea -squirt, 294 

Polymorphism, 45 

Polype, a name applied to a mem- 
ber of a Coelenterate colony, or 
to a simple Ccelenterate, e.g. a 
sea-anemone, 16, 41 

Poole, 35 

Portland, 35 

Preoperculum of Coitus, 301 

Proboscis of Arenicola, 30 
of Nemerteans, 120 
of Nereis pelagica, 87 

Propodite, 174 

Prostomium of Nereis pelagica, 84, 

Protective coloration, 14, 256 

Radial shield of Opkiothrix fra- 

gilis, 129, 130 
Radial or radiate symmetry, 29, 

126, 143 
Radula, 227 

of Chiton, 228 

of limpet, 226 
Rostrum, 154 

of Decapods, 163 

of Galathea, 178 

of Hippolyte varians, 167 

of lobster, 173 

of Nephrops, 174 

of Palcemon, 165 

St. Andrews, 35, 63, 81, 127, 193 
Scale of crayfish's antenna, 156 

of Mysis, 212 
Scales of Polynoids, 95, 96, 97, 

98, 102, 107 
Scarborough, 35 
Segmentation, 85 

of Chiton, 229 
Self-mutilation, 11, 126 
Septa of bristle- worms, 91, 92 



Siphon of whelk, 234, 844 

Siphonoglyphes, 66 

of Actinoloba dianthus, 74 

Skin-gills, 128 

Spawn of Doris, 253 

of Doto coronata. 259 

Spicules of Alcyonium, 75 

Spicules or needles of sponges, 36 

Sporosacs of sea-firs, 41> 42, 46, 
48, 49, 50, 58 

Squame of crayfish's antenna, 156 

Stinging-cells, 29 

Stolons, basal connecting pro- 
cesses of sea-firs, shown in 
Figs. IX. and XVII., 29, 51 

Stone canal of sea-urchin, 138 

Sub-chelate, 169 

Sub-equivalve, 275 

Swimmerets, 154, 156 

Swimming movements of Deca- 
pods, 253 [13 

Symbiosis or animal partnerships, 

Tail fan of crayfish, 157 

Teeth of Cyprina islandica, 279 

of Ophiura, 131 

of sea-urchin, 136 
Teignmouth, 35 
Telson, 155 

of Mysis, 212 
Tenby, 35 

Tentacle scales of Ophiura, 130 
Tentacles of Cucumaria, 143, 
144, 145 . 

Tentacles of heart-urchin, 142 
Tentaculocysts of Aurelia, 77 
Test of common sea-urchin, 135 
of Echinocardium cordatum, 
of Tunicate, 291 [140 

Thoracic membrane of Serpula, 


Tooth-papillse of brittle-stars, 131 
Torbay, 264 
Torquay, 35, 63, 193 
Tube of Pectinaria belgica, 114 
of Pomatocerostriqueter, 117 
of Serpula vermicularis,\!7 
Tube-feet of Asterias rubens, 126, 
of Cucumaria, 144 [127 
of heart-urchin, 142 
of Ophiothrixfragilis, 130 
of sea-urchin, 137 

Uropods, 157 

Velum, or veil, of medusoids, 47 
Ventral fin of coal-fish, 298 

"Water-vascular system, 126 
Weymouth, 35, 264 
Whitby, 35 
Woolacombe, 289 

Zoea, 205 

of Thiapolita, 328 
Zooid, a member of an animal 
colony, 41 



Figures in italics refer to illustrations ; those in thick type to the 
page on which the animal is described. 

Acmcea testudinalis, 23, 24, 232, 

233, 246 

A. mrginea, 232, 246 
Acorn-shells, 6, 219 
Actinia mesembryanthemum, 65, 

67, 80 
Actinoloba dianthus, 16, 73, 73, 

80, 317 

Adamsia palliata, 12, 187 
Alcyonaria, 74, 80, 81 
Alcyonium digitatum, 16, 20, 74, 

80, 317 

Ammodytes lanceolatus, 311, 316 
A. toUanus, 9, 311, 316 
Amphictenidae, 123 
Amphipoda, 14, 215, 223 
Amphiporus lactiftoreus, 120 
Amphithoe podoceroides, 217 
Amphiura elegans, 133, 148 
Anarrhichas lupus, 307 
Ancula cristata, 256, 256, 263 
Angler, 303 
Annelids, 29, 32 
Anomia ephippium, 270, 287 
Anthea cereus, 20, 65, 81 
Anthozoa, 64, 80 
Aphrodite aculcata, 96, 103 
Aphroditidae, 102, 122 
Aplysia hybrida, 250, 250, 263 
Aporrhais pes-pelecani, 240, 246 
Arenicola piscatorum, 30, 88, 92, 

115, 119, 122, 124, 321 
Arenicolidse, 122 
Aristotle's lantern, 136 
Arthropods, 30, 32 

Ascidiella mrginea, 295 
Asiphonate bivalves, 269 
Astacidae, 171, 192, 208 
Astacus flumatilis, 171 
Asterias rubens, 127, 147, 149, 


A. glacialis, 127, 147, 149, 323 
Asteroids, 126, 147 
Asterophyton, 223 
Atelecyclus heterodon, 191, 193, 


Aurelia aurita, 76, 81 
Azygobranchia, 230, 246 

Balanus balanoides, 219, 224 

Beroe, 79, 81 

Bivalves, 7, 31, 32, 227, 266 et seq. 

Blackamoor's tooth, 245 

Blennidse, 315 

Blennius pholis, 10, 306, 307, 


Blenny, 10, 308 
Bony fish, 297 
Botrylloides, 296 
Botryllus, 296 

Bottle-brush coralline, 56, 56 
Brachiopods, 268 
Brachyura, 194, 207, 208 
Bristle-worms, 83 et seq. 
Brittle-stars, 126, 129, 147 
Brown cat, 98 
Buccinum undatum, 244) 244, 


Bullhead, 301, 302, 303, 309 
Butter-fish, 307 




Calyptoblastea, 44, 49, 61, 81 
Campanularia flexuosa, 51, 52, 

61, 62 

Campanularidfe, 61 
Campanulinidee, 53, 61 
Cancer pagurus, 26, 200, 208 
Caprella linearis, 218 
C. tuberculata, 219 
Caprellicke, 223 [208 

Carcinus mcenas, 26, 153, 200, 
Cardium edule, 282, 288 
Candida, 164, 170, 172, 208 
Carpet-shell, 868, 281 
Catometopa, 202, 207, 208 
Cave-dwelling anemone, 14, 70 
Centronotus gunnellus, 308, 308, 


Cephalopoda, 228, 285 
Chsetopoda, 83, 102 
Chiton fascicularis, 229, 246 
C. marginatus, 228, 229, 246 
G. ruber, 230, 246 
Chitonidae, 231, 246 
Chlorhsemidse, 123 
Chrysaora, 77 
Ciona intestinalis, 291 
Cirratulidee, 123 [124 

Cirratulus cirratus, 111, 119, 123, 
Cirripedia, 219, 224 
Clava squamata, 45, 45, 61 
C. multicornis, 61 
Glytia johnstoni, 51, 62, 326 
Cockle, 282 

C(Blentera, 29, 32, 40, 61 
Corals, 75 

Corellaparallelogramma, 292, 292 
Coryne pusilla, 46, 61 
Corystes cassivelaunus, 189, 190, 


Corystidse, 189, 192, 193, 208 
Cottidse, 315 

Coitus scorpius, 34, 301, 301, 315 
C. bubalis, 302, 315 
Cowry, 245 
Crangon vulgaris, 168 
Creeper, 107, 119 
Crenella marmorata, 271, 273, 


Crinoids, 126 

Crumb-of-bread sponge, 28, 32, 37 
Crustacea, 30, 32, 150 et seq. 

Ctenophora, 79, 81 

Cucumaria lactea, 143, 148, 149 

C. pentactcs, 149 

C. planci, 144 
Cuttles, 31, 228, 285 
Cyanea, 77 

Cyclometopa, 199, 207, 208 
Cydopterus lumpus, 21, 304. 315 
Cyprea europcea, 245, 247 
Cyprina islandica, 279, 287, 289 

Dab, 314 

Daisy anemone, 81 
Daisy brittle- star, 132 
Dasychone bombyx, 116, 123, 124 
Dead men's fingers, 16, 74 
Decapoda, 153, 170, 207, 223 
Dendronotus arborescens, 256, 264 
Discoboli, 315 
Discomedusse, 81 
Dog-periwinkle, 241 
Donax vittatus, 280, 288 
Doris bilamellata, 252, 263 

D. johnstoni, 251, 252, 263 
D. pilosa, 254, 263 

D. repanda, 252, 263 

D. tuberculata, 251, 263 

Doto coronata, 13, 259, 259, 264 

Echinocardium cor datum, 9, 139, 


Echinoderms, 30, 32, 125 et seq. 
Echinoids, 126, 148 
Echinus esculentus, 135, 138, 138, 


E. miliaris, 135, 148, 149 
Edible crab, 26, 151, 200, 208 
Edible mussel, 71, 267, 271 
Eledone cirrosus, 286 
Entomostraca, 219, 224 
Eolis coronata, 22, 260, 264 
E. papillosa, 260, 264 

E. rufibranchialis, 261, 261, 264 
Esop prawn, 151 
Eulalia viridis, 101, 103, 119 
Eulamellibranchs, 270 
Eupagurus bernhardus, 193 
E. prideauxii, 193 

Father-lusher, or lucky proach, 



Fiddler- crab, 201 
Filibranchs, 270, 287 
Filigrana implexa, 118 
Fishing-frog, or angler, 303 
Flatfish, 312 
Flounder, 312, 314 
Flustra, 120 
Flustrella, 122 
Fusus antiquus, 244, 247 

F. islandicus, 244, 245, 247 

Gadidje, 316 

Gadus virens, 298, 299, 316 

Galathea, 22, 175, 189 

G. squamifera, 177, 177, 192 
G. strigosa, 178, 192 
Gammarus locusta, 217 
Gasteropoda, 31, 33, 227, 246, 264 
Gasterosteidae, 315 
Gasterosteus, 10 

G. aculeatus, 310, 315 

G. spinachia, 309, 315 

Glycera, 119, 122, 321 

G. capitata, 108, 109, 124 

G. gigantea, 109 

Glyceridse, 108, 119, 122 

Goby, 21 

Goniodoris nodosa, 254, 255, 263 

Gooseberry sea-squirt, 294 

Gorgon-headed starfish, 223 

Grantia ciliata, 39 

G. compressa, 28, 38 

Gunnel, 307, 308, 308 

Gyranoblastea, 44, 61, 81 

Haleciidse, 53, 62 [319 

Halecium halecinum, 53, 54, 63, 
HalicJiondria panicea, 37 [81 
Haliclystus octoradiatus, 78, 7S, 
Heart-urchin, 9, 139, 321 
Helcion pcllucidum, 23, 232, 246 
Henricia sanguinolenta, 127, 147, 

149, 319 

Hermit-crab, 12, 183, 184 
Herring-bone coralline, 53, 319 
Hippolyte cranchii, 167. 170, 321 
H. varians, 167, 170 
Holothurians, 126, 143, 148 
Homarus vulgaris, 152, 171, 173, 

Horse-mussel, 271, 273 

Hyas araneus, 14, 196, 197, 207 
H. coarctatus, 198, 207 
Hydractinia echinata, 12, 41, 61, 


Hydrallmania falcata, 56, 63 
Hydra-tuba, 76 
Hydrozoa, 43, 61, 81 

Idotea tricuspidata, 215, 216, 216, 


Inachus dorhynchus, 199, 207 
/. dorsettensis, 14 
Invertebrates, 27, 31 
Isopoda, 215 

Jelly-fish, 17, 64, 76 

Lacuna, 236 

Lafoea dumosa, 53, 63 

Lafoeidse, 53, 62 

Lamellar ia per spicua, 241, 246 

Lamellibranchs, 227, 266 et seq. 

Lamp-shells, 268 

Leaf-worms, 98, 119 

Lepas anatifera, 220 

Leptoplana tremellaris, 119 

Lima Mans, 273, 277, 287, 289 

Limpet, 6, 24, 226, 231 

Linens marinus, 120, 121, 121 

Lithodes maia, 187, 188, 193, 195 

Lithodidse, 192, 193, 208 

Littorina, 236 

L. littorea, 238, 246 

L. neritoides, 238 

L. oUusata, 238, 246 

L. patula, 238 

L. rudis, 238, 246 

Living film, 119 

Lobster, 152, 171, 192 

Lob-worm, 11, 30, 83, 92, 115 

Loligo vulgaris, 286 

Lophius piscatorius, 303, 315 

Lucenaria, 78, 78 

Lucenarise, 81 

Luidia, 134 

Lumpsucker, 21, 304 

Lutraria, 9, 321 

Lutraria elliptica, 283, 288 

Macrura, 162, 208 
Madra solida, 280, 287 



M. stultorum, 280, 280, 287 
M. subtruncata, 280, 287 
Maia squinado, 195, 207 
Malacostraca, 219, 223 
Masked crab, 189 
Medusoids, 42, 46 

of Clytia, 60 

of Obelia, 60 
Meiribranipora, 122 
Modiola (or Crenella) marmorata, 

12, 271, 273 

M. modiolus, 271, 273, 287 
Mollusca, 31, 32, 225 et seq. 
Mya, 9 

M. arenaria, 283, 288 
M. truncata, 283, 283, 288 
Mysidffi, 211, 223 
Mysis, 161 

M. flexuosa, 209, 211, 212, 223 
M. lamornce, 214, 223 
M. vulgaris, 213, 223 

of Norway lobster, 205 
Mytilus edulis, 267, 271, 272, 287 

Nassa incrassata, 242, 247 
N. reticulata, 242, 247 
Natantia, 163, 164, 170, 208 
Nauplius of Peneus, 327 
Nematoda, 82 
Nemertea, 29, 82, 120 
Nephrops norvegicus, 151, 171, 

174, 192, 322 
Nephthydidse, 108, 122 
Nephthys, 98, 119, 122 
N. hombergii, 108, 123 
Nereidse, 122 

Nereis cultrifera, 106, 119, 123 
N. dumerilii, 106, 123, 124 
N.fucata, 12, 94, 106, 123 
N. pelagica, 84, 85, 104, 119, 123, 


N. virens, 107, 119, 123 
Nerine, 119, 122, 321 
N. coniocephala, 110, 124 
N. vulgaris, 110, 124 
Noctihica, 28 
Norway lobster, 151, 171, 174, 

192, 322 

Notodelphys ascidicola, 294 
Nudibranchs, 13, 248 
Nymphon, 222, 224 

Obelia geniculata, 51, 51, 62 
Octopus vulgaris, 286 
Old maid shell, 9, 283 
Oligochsetes, 83 
Ommastrephes todarus, 286 
Opercularella lacerata, 53, 62 
Ophidiidse, 316 
Ophiocoma nigra, 149 
Ophiopholis aculeata, 132, 148 
Ophiothrix fragilis, 129, 131, 147 
Ophiura albida, 133, 148 
0. ciliaris, 133, 148 
0. lacertosa, 133 
Ophiuroids, 126, 129, 147 
Opisthobranchia, 230, 248 et seq. 
Opossum-shrimp, 205, 209 
Ostrea edulis, 278, 287 
Otter-shell, 9, 283 
Oxyrhyncha, 195, 207, 208 
Oyster, 278 

Paddle-cock, 305 
Paddle-worm, 99, 119 
Paguridre, 183, 192, 193, 208 
Pagurus bernhardus, 184, 186, 


P. prideauxii, 187, 322 
Palcemon serratus, 151, 165, 170 
P. squilla, 151, 165, 170 
Palinuridse, 174, 192, 208 
Palinurus vulgaris, 174, 178, 192 
Palolo Avorm, 105 
Paludina, 236 
Pandalus annulicornis, 151, 166, 

Patella vulgata, 23, 226, 226, 231, 


Peachia, 9, 321 
Pearly nautilus, 228 
Pecten maximus, 276, 287 
P. opercularis, 31, 274, 287 
P. pusio, 27 Q, 287 
Pectinaria, 94, 119, 123 
P. belgica, 114, 115, 124 
Pediculati, 315 
Pelican's foot, 240 
Peltogaster paguri, 185, 220 
Peneus, 164, 172, 327 
Pennatula phosphor ea, 75, 80 
Periwinkles, 236, 238 
Pholas, 8, 284, 289 



P. Candida, 285, 288 
P. crispata, 8, 285, 288 
Phoxichilidium femoratum, 222, 

Phyllodoce lamelligera, 99, 100, 

103, 119 

P. maculata, 99, 103, 119 
Phyllodocidre, 98, 122 
Physalia, 63 

Pinnotheres pisum, 202, 208 
Pisa, 198 
Plaice, 313, 314 
Pleurobrachia, 79, 81, 330 
Plcuronectes flesus, 314, 316 
P. limanda, 314 
P. platessa, 314 
Pleuronectidse, 316 
Plumose anemone, 16, 72, 73 
Plumularia setacea, 29, 57, 57, 63 
Plumularidse, 57, 62 
Polycarpa rustica, 295 
Polyccra quadrilineata, 255, 263 
Polycheeta, 30, 83, 93, 102 
Polynoe, 119 

Polynoe imbricata, 95, 103 
Polyzoa, 121 

Pomatoccros triqueter, 117, 124 
Porcelain-crab, 175, 179 
Porcellana, 175, 189 
P. longicornis, 180, 183, 192 
P. platycheles, 179, 182, 191, 192 
Porcellanidse, 192, 208 
Portuguese man-of-war, 40, 45, 59, 

63, 81 

Portumnus variegatus, 201, 208 
Portunus depurator, 202 
P. marmoreus, 202, 208 
P.puber, 201, 208 
Prawn, 151, 163 
Protozoa, 27, 32 
Pseudo-lamellibranchs, 270, 287 
Purple heart-urchin, 143 
Purple-tipped urchin, 135 
Purpura lapillus, 241, 247 
Purse-sponge, 28, 32, 38 
Pycnogonida, 221, 224 
Pycnogonum littorale, 221, 224 

Rag- worms, 109 

Razor-shell, 2, 284 

Reptantia, 163, 170, 192, 207, 208 

Ribbon-worm, 9, 32, 120 
Rissoa, 240 

Rock lobster, 174, 192 
Sabellaria alveolata, 7, 83, 118, 


Sabellidse, 116, 123 
Sabellids, 119 

Sacculina carcini, 220, 221, 224 
Saddle-oyster, 270 
Sagartia bellis, 81 
S. miniata, 81 
S. troglodytes, 70, 70, 81 
Saithe, or coal -fish, 298, 298 et seq. 
Sand-eel, or sand-launce, 9, 311 
Sand-hoppers, 215, 216, 817 
Sand-mason, 7, 111 
Sand-stars, 130, 133 
Sarsia, 17, 46, 47 
Saxicava rugosa, 8, 284, 288 
Scale-worm, 95 
Scallops, 31, 274 
Scaly squat-lobster, 177, 177 
Schizopoda, 164, 211, 223 
Scyphomedusse, 81 
Scyphozoa, 64, 80 
Sea-cucumbers, 126, 143,^, 148 
Sea-firs, 17, 43 
Sea-gooseberry, 79, 330 
Sea-hare, 250, 250 
Sea-lemons, 250 
Sea-lilies, 126 
Sea-mat, 121 
Sea-mouse, 96 
Sea-nettles, 40 
Sea-pen, 75 

Sea-scorpion, 21, 34, 801, 301 
Sea-slugs, 248 
Sea-snake, 120, 121 
Sea-spiders, 221, 224 
Sea-squirts, 290, 292, 295 
Sea-urchin, 126, 135, 138, 148 
Segmented worms, 29, 32 
Serpula vermicularis, 6, 90, 94, 

117, 117 

Serpulidse, 116, 123 
Serpulids, 119 

Sertularella polyzonias, 54, 63 
Sertu laria putnila, 55, 63 
Sertularidae. 54, 62 
Shanny, 306 
Shore crab, 26, 151, 153, 200 



Shrimp, 168 
Sickle-coralline, 56 
Siphonate bivalves, 269 
Siphonophora, 59 
Siphonostoma, 94, 116 
Siriella armata, 214, 223 
Skenea planorbis, 240 
Smooth anemone, 65 
Solaster end&ca, 129, 147 
S. papposus, 128, 128, 147 
Solen, 9, 321 
S. ensis, 284, 288 
S. siliqua, 284, 288 
Spatangus purpurcus, 143, 148 
Spider-crabs, 14, 195, 197 > 321 
Spiny spider-crab, 195 
Spiny starfish, 149 
Spionidse, 122 
Spirorbis, 6, 83, 118 
Sponges, 28, 32 
Starfish, 125-9, 147, 149, 322 
Stenorhynchus longirostris, 322 
S. phalangium, 198, 207, 322 
Sthenelais boa, 97, 97, 103, 119 
Stickleback, 10, 309 
Stone-crab, 187 
Styelopsis grossularia, 294 
Sun-star, 128, 149 
Swimming-bells, 17, 47, 326 
Swimming crabs, 201 
Syllis, 105 

Synapta, 9, 144, 148, 321 
S. inhcerens, 145 
Syncoryne eximia, 46, 61 

Talitrus saltator, 216 

Tapes pullastra, 268, 268, 281, 


T. virgineus, 282 
Tealia crassicornis, 67, 68, 68, 80 

Teleosteans, 297, 315 
Tellina tennis, 281, 288 
Terebella, 7, 83, 90, 113, 123 
T. conchilega, 111, 113, 124 
Terebellidse, 123 
Terebellids, 111, 119 
Themisto brevispinosa, 215 
Thick-horned anemone, 67, 68 
Thuiaria thuia, 56, 56, 63 . 
Tortoise-shell limpet, 23, 24, 233 
Tower-shells, 240 
Triopa claviger, 255, 263 
Trochus cinerarius, 235, 246, 247 
T. lineatus, 247 
T. umUlicatus, 247 
T. zizyphinus, 285, 246 
Trophonia plumosa, 115, 119, 124 
Tubularia indivisa, 29, 32, 48, 

49, 61 

Tunicates, 31, 290 
Turbellaria, 119 
Turritella communis, 240, 246 

Unsegmented worms, 29, 32 

Velvet-crab, 201 

Venus striatula, 281, 288 

Viviparous blenny, 308 

Water-flea, 219, 294 

Weever, 34 

Whelk, or buckie, 844, 244 

White cat, 98, 108 

Wolf-fish, 307 

Wrinkled swimming crab, 202 

Zoantharia, 80, 81 
Zoarces viviparus, 308, 315 
Zoophytes, 12, 17, 40, 41, 43 
Zygobranchia, 230, 246 


MM 01 WOH G 


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