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REPORT ON THE MARINE ZOOLOGY OF
OKHAMANDAL IN: KATTIAWAR
Marine ZooLoGcy oF OKHAMANDAL. [Frontisprece.
HIS HIGHNESS SAYAJI RAO IIL, GAIKWAR, G.C.S.L.,
SENA KHAS KHEL SAMSHER BAHADUR,
MAHARAJA OF BARODA.
REPORT
TO THE GOVERNMENT OF BARODA ON THE
MARINE ZOOLOGY OF
OKHAMANDAL IN KATTIAWAR
BY
JAMES HORNELL, F.L.S.
Bureau of Fisheries, Madras, and formerly Marine Biologist to the Government of Ceylon
WITH SUPPLEMENTARY REPORTS ON SPECIAL GROUPS BY OTHER ZOOLOGISTS
PARKL £
LONDON
WILLIAMS AND NORGATE
14, HENRIETTA STREET, COVENT GARDEN, W.
1089
be
RicHARD Cxiay AND Sons, LimirEp,
BREAD STREET HILL, E.C., AND
BUNGAY, SUFFOLK.
PREFACE
THE investigation which furnished the collections whereon are based the reports
comprised under the present cover owed its inception to the enlightened policy
pursued by His Hicuness Manarasa Sayast Rao IIL, Garxwar or Baropa, for
the educational and material development of the historic State which is so fortunate
as to be ruled by him.
Naturally the technical inquiry at Okhamandal which His Highness honoured
me by entrusting to me to carry out, had the improvement of the economic marine
resources of that district as its foremost object, and indeed its raison détre
from an administrative standpoint; yet, with a generosity towards the furtherance
of pure science too rarely found among the heads of States, His Highness most
willingly agrecd to bear the entire expense involved in the publication of any
scientific reports written by specialists upon the zoological collections made during
the inquiry. He was also pleased to express the wish that such papers should be
presented in the best possible form, and that no efforts were to be spared in their
satisfactory illustration.
Hitherto the attention of zoologists dealing with the fauna of Indian seas
has been directed in the main towards the investigation of the species inhabiting
the deeper zones; in this connection I have only to cite the classic monographs
with which the name of the Indian Marine Surveying steamer ‘“ INVESTIGATOR”
and of Magor Axcoox, F.R.S., late Superintendent of the Calcutta Museum (Natural
History), will ever be associated with all honour. Comparatively little attention
vi PREFACE
has been bestowed upon the fanna of the littoral zone and inshore shallow water,
except in the case of the Gulf of Mannar, where that of the Ceylon side has been
ably dealt with by Pror. Herpmay, F.R.S., and the workers asseciated with him,
while the zoology of the Indian side has received considerable attention from
Dr. THursTon, the versatile Superintendent of Madras Museum, from Pror. DEnpy,
F.R.S., and other well-known zoologists in England and India. It is hoped, therefore,
that the following reports, dealing as they do exclusively with the marginal waters
of a little-known region on the West Coast of India, may prove valuable as a
local monograph—the first of its kind in India—and from the standpoint of
geographical distribution.
In Part I. I have to acknowledge with grateful thanks the invaluable assistance
of Mr. THomas SouTHweE tu, A.R.C.S8., F.L.8., Proressor J. Arrour THomson, M.A.,
Mr. Grorce Crane, B.Sc. of Aberdeen, and Srr CnHaries Extot, Sheffield
University. The first-named, whom it was my good fortune to have as my
scientific assistant during the last eighteen months of my service in Ceylon, besides
contributing a report on the ANomuRA, collaborated with me in the description of
a new species of PinNoTERES and also afforded me much help in other directions.
Mr. SourHwett has now in hand a report upon the Actinozoa which I hope
to include in Part II.
The report on the Atcyonartans of Okhamandal, now furnished by Pror.
J. A. THomson and Mr. Grorce Crane, is particularly valuable on account of the
beautifully executed coloured plate which accompanies it and which renders identifi-
cation easy of the principal species of this group found in the waters of the Gulf
of Kutch. The short contribution by Dewan Banapur V. M. Samarra is of
great interest as indicating, among other things, how a wise and progressive rule,
such as that exercised by His Hicuness THE GAEKWAR, has the power of penetrating
every department of government and of endowing each with a portion of the
same spirit of enlightened progress.
The whole of the photographs reproduced, except the frontispiece, are the
work of the Vividha Kala Mandir, Baroda, whose representative accompanied me
PREFACE vii
during the greater part of the time spent in Okhamandal, and whom I am glad to
have this opportunity to thank for the great assistance he rendered, often enough
under circumstances of great personal discomfort.
As regards the groups of animals yet to be described I have received from
Pror. A. Denpy, F.R.S., our greatest authority upon the SponeEs, the promise
of a report, which is the more valnable seeing that this phylum is especially rich
in species in the collections from Okhamandal. Mr. Epwarp T. Browne, M.A.,
University College, London, has undertaken to report upon the Mepusa, while
Miss THorneLy will report upon the Hyprozoa and Ponyzoa and _ Pror.
Herpman, F.R.S. upon the Ascrprays. On my own part I hope to furnish
contributions upon certain of the remaining groups, together with a general
survey of the geographical and vertical distribution of the more noteworthy
species and groups represented in the collections.
For the benefit of those readers whose acquaintance with India is not
intimate, it may be of interest to mention that Baroda is one of the greatest of
the self-governing States of India, having an area of over 8,000 square miles and
a population at the last census (1901) verging upon 2,000,000. The present
Maharaja is essentially a man of action; he may dream dreams, but his waking
hours are devoted to strenuous effort to turn them into practical realities. To
the introduction of new industries and the improvement of indigenous ones he has
given the greatest attention; he has travelled far and wide through Europe and
America to gather ideas and information at first hand pertinent to the schemes
he is elaborating for the economic and social advancement of his State. His
Highness is specially concerned in fostering the arts of the hereditary craftsmen of
India, whose productions tend to deteriorate and decay as the cheap and shoddy
wares of Europe and the new Japan crowd them from the shelves and counters
of the bazaars.
As the basis of all reform, the Maharaja is convinced of the necessity of
placing within the reach of even the humblest of his subjects educational
opportunities well-considered for their particular requirements; at the ‘present
vili PREFACE
moment education is not only free, but is compulsory as well in Baroda. By
the enlightening and levelling influences of this system of universal education
His Highness hopes so to raise the lower castes that the fetters of caste itself
will automatically fall away, but so gradually that the evils of a sudden
social revolution shall be avoided. The Maharaja is certainly entitled to be
considered the most important personal factor in social reform in India;
indeed none but a powerful and orthodox Hindu ruler such as he is dare to
approach with any chance of success the domestic problems which fetter
Indian society. Among other measures of reform, he has done much for the
cause of female education, not only within the bounds of his own State but
throughout all Hindu India; he is a staunch advocate of a relaxation of the
rigorous enforcement of the purdah system, and by his enactments he has so
raised the minimum marriage age, that the evils of child marriage have been
put an end to in Baroda.
Those interested in the social and economic regeneration of India should
study well and in detail the history of Baroda during the present reign, for
therein they will find the record of much attempted and much accomplished
in spite of many failures. The present volume is the story of the work done
in one of these pioneering attempts.
In conclusion, I desire to thank once more all the Baroda officials who gave
their ungrudging help. to me in the present investigation; I wish them long life
and every possible success in their careers, and especially do [ wish all honour and
happiness to Dewan Banapur V. M. Samarru, who, I understand, is about to
retire from the service of his State at an early date.
My hearty thanks are also due to Mayor A. K. Conpon, the Assistant British
Resident at Dwarka during my visit, for his great hospitality and unvarying
kindness and courtesy. I shall ever retain a vivid recollection of the warmth
of the welcome which he was so good as to extend to me. To observe the
wonderfully good relations subsisting between him and the officers and men of
the Okha battalion was not the least interesting of my experiences, and I
PREFACE : ix
trust the battalion may always have a Commander as sympathetic and careful
of their well-being as Masor Conpon was.
The prosperity of Baroda is a very sincere wish in my heart, and I trust
that His Hicuness tHe Manarasa GarKwarR may long be spared to guide its
destinies upon the path of enlightenment and social and material progress ;
may the great reforms he has at heart come early to fruition and maintain
Baroda’s well-founded claim to be the most enlightened self-governing State in
India.
JAMES HORNELL.
Mapras, April 10¢h, 1909.
CONTENTS OF PART I
Portrait or H.H. Mawarasa Sayas1 Rao, GaEKwaR or Baropa . ‘ ‘ ‘ Frontispiece
PREFACE
I.—The Marine Resources or OkuHamanpaL. By James Horne, F.L.S. (Hight Plates
and nine Text-figures)
II.—The Inpusrrian DEvELopMENT oF OkHAMANDAL. By V. M. Samarra, B.A.
III.—The Anatomy or Puacuna Pracenta. By James Horwewz, F.L.S8. (Six Plates) .
IV.—Descrierion or A New Specius or Pinnorerus. By James Horney, F.LS8., anp
Tuomas Sournwett, A.R.C.S., F.LS. (One Plate)
V.—The ANnomura or OkHAmMANDAL. By Tuomas Souruwe i, A.R.C.S., F.L.S. (One Plate).
VI.—The AtcyonariAns or OkHAMANDAL. By J. Arruur Tuomson, M.A., anp Georce Cranr,
B.Sc. (One Coloured Plate and two Text-figures)
VII.—The Nuprprancns oF OxkHAMANDAL. By Sir Cuartes Exior, with a note by
J. Horne.i on the presence of Symbiotic Alge in Mrtise Rane, with Text-figures
PAGE
Vv
35
137
*yaau9 dunk) ay} JO YU Y}NOS By} WO. VAIEMG JO MAIA
Tid A [ppomg 60
WW VjyNy vy
| 3ALV1d ‘SAIYLSNANI ANIQDVN IWONVWVHHO SO ADOIO0Z ANIYVW
REPORT
TO THE GOVERNMENT OF BARODA
ON THE PROSPECTS OF
ESTABLISHING A PEARL FISHERY
AND OTHER MARINE INDUSTRIES ON THE
COAST OF OKHAMANDAL,
BY
JAMES HORNELL, F.LS.,
Bureau of Fisheries, Madras, and formerly Marine Biologist to the
Government of Ceylon.
By arrangement with the Ceylon authorities my services were lent to the
Government of Baroda at the end of 1905 for the purpose of investigating the economic
marine resources of the coast of Okhamandal, an outlying portion of His Highness
the Gaekwar’s possessions, forming the north-west extremity of the peninsula of
Kattiawar. Pearl oysters had been noted in small numbers along the coast-line, and
my attention was to be directed specially to an examination of the possibilities of
developing a remunerative pearl fishery.
Leaving Ceylon on 30th November, 1905, I reached Dwarka, the chief port of
Okhamandal, six days later. By the courtesy of the authorities, His Highness’s steam
launch “ Pari” had been sent round to Dwarka, and was awaiting my arrival, while the
Vahivatdar, the principal revenue officer of Okhamandal, Mr. Kashinath B. Pradhan,
with the assistance of Mr. Sunderlal, the Executive Engineer, had all arrangements
perfected for the immediate commencement of the investigation. Without the
abounding energy and intimate local knowledge possessed by Mr. Pradhan, and the
professional skill of Mr. Sunderlal, the comparatively short time at my disposal
would have proved inadequate to that extensive and minute examination of the
littoral waters necessary before I could formulate conclusions sound and of real economic
value.
B
2 OKHAMANDAL MARINE ZOOLOGY REPORT
It had been a question of anxious consideration as to the time best suited to carry
on the investigation, especially as my duties in Ceylon precluded my being away save
in summer (May to September), or during December and part of January. The latter
period was, as I have said, the period eventually chosen, the principal reason being
that at this time the weather is normally sufficiently favourable to allow of investigation
being carried on both in the channels around Beyt Island, upon the reefs adjoining, and
also upon the exposed seaward or western coast of Okhamandal promontory.
Results showed that this choice was the best possible, as at any other time the
violence of the south-west monsoon renders the western coast inaceessible.
Fig, 1.—Shells of the black-lip Pearl Oyster (IZ. margaritifera) on sale in the Dwarka bazaar.
They hail most probably from the Persian Gulf.
A considerable amount of preliminary evidence had been eathered by Mr. Pradhan,
the Vahivatdar, at the instance of the Sar Subha of His Highness the Gaekwar’s State,
the cultured and progressive Dewan Bahadur V. M, Samarth, B.A., to whose energy
and enlightened foresight the inception of the preseut inquiry is largely due.
The facts pointing to the possibility of developing the resources of the seas
and shores of this portion of the Baroda dominions were principally the two
following, viz. :—
(a) The neighbouring State of Jamnagar, of which the coast-line is a continuation
HORNELL—MARINE RESOURCES 3
eastwards of the northern sea margin of Okhamandal, has for a long period carried on a
small and primitive pearl fishery in the shallows on and around the rocky reefs that
stud the southern margin of the Gulf of Kutch.
(b) Rumours of finds of pearl oysters and of pearls, by fishermen and others upon
the Okhamandal coast, had several times come to the knowledge of the authorities, who
had in consequence instituted search several times in the endeavour to ascertain the
real facts.
Difficulties in obtaining divers, reliable as well as competent, were met with, and
no conclusive evidence had been obtained when Mr. Samarth and Mr. Pradhan took
up the investigations once more.
No local divers are procurable in the Gulf of Kutch, the Jamnagar pearl fishery
and the Okhamandal chank fishery being carried on by the primitive method of wading
in the shallows, the fishermen taking advantage of the great fall of level that occurs
on the days of high spring tides. Accordingly, besides including dredges and
water-telescope in the apparatus taken, I also took with me, upon the suggestion of the
Baroda Government, three of the best of the divers who were then permanently
retained by the Ceylon Pearl Fishery Department for periodic inspection of the
pearl banks.
I should add that I was also informed that chank-fishing is an historic minor
industry on the Okha coast, and that edible oysters are also found in several bays and
creeks.
Dredging, diving, and shore collecting were carried on almost continuously from
9th December, 1905, to 13th January, 1906, during ten days whereof I had the great
‘pleasure and advantage of the advice, companionship, and hospitality of the Sar Subha,
Dewan Bahadur V. M. Samarth. I need not say that his countenance of my work
facilitated and expedited matters very greatly, and words fail me wherein to express
my appreciation of his personal kindness and his untiring zeal in ensuring that no
effort should be spared to help the investigation forward. In lonely and unfamiliar
circumstances it was indeed an unlooked-for delight, and one the more pleasant by being
unexpected, to meet one so widely read and deeply versed in the literature of both
Hast and West as Mr. Samarth. The evenings passed in discussion after the day’s
work was completed, will remain as delightful memories of Dwarka and Beyt through
the rest of my life, and make the remembrance of this investigation a joy ever to
be recalled with pleasure.
The performance of the Tamil divers, taken from Ceylon, was disappointing, and
had I not had the dredges to fall back upon the inquiry could not have been carried
through successfully. The cause of the unsatisfactory diving lay in the chilliness of
the December and January winds and the comparatively low temperature of the water.
We may console ourselves with the thought that divers of no other race available in
India would have given better results. The same trouble would have been found had
B 2
4 OKHAMANDAL MARINE ZOOLOGY REPORT
Arab divers been employed. My experience is that, if anything, Arabs are more
sensitive to cold than Tamils. In the Persian Gulf, for instance, no diving for pearl
oysters goes on during the winter months—those during which we worked at
Okhamandal—work being confined to the hot summer months of June to September ;
the two intensely hot months of July and August are considered the best and constitute
the height of their season.
In consequence, while the results obtained are sufficient to enable me to
pronounce definitely upon most matters which I set out to examine,it must be
remembered that the investigation has not been exhaustive. Five weeks’ work in
marine biology, carried out single-handed, is inadequate to do more than clear away
initial difficulties and misconceptions, and to show the most suitable lines for the more
detailed investigations of my successors. It has been good pioneering, and just
sufficiently ample to enable the economic potentialities of the locality to be assessed
for some of the most likely organisms.
The collections made of marine animals and plants are large and important for
many groups. Sponges, ccelenterates (especially hydroids and alcyonarians), crustaceans,
worms and alge are notably well represented. The plankton (minute free-swimming
life of the sea) [ could wish to comprise a larger number of samples, but the material
will be found ample, I believe, to enable an approximate census to be made both of the
relative and the absolute proportions present in the Okha waters of the chief organisms
which contribute to the dietary of the two forms of pearl oysters found in this locality.
These collections have now been sorted and have been placed in the hands
of specialists to be reported upon in detail.
It may be well to point out here that the examination and identification of the
hosts of animals and plants comprising the marine fauna and flora of the Gulf of Kutch
have much more than an academic and purely scientific interest. Within the assemblage
are comprised enemies of the pearl oysters—sponges, corals, starfishes, worms, fishes—
some that burrow into and destroy the commercial value of the shell, others that
kill oysters directly and yet others that compete for food and space and foothold
with the oyster, and which, if excessively numerous, may entail starvation on the
molluse and even elbow it out of existence locally. The comparative abundance
of seaweeds is a factor of great moment, for their spores at certain seasons constitute
a great proportion of the food of oysters, while the rankness of their growth, as
I can testify, so masks and hides the presence of oysters that pearl-fishing in
December and January is impossible in practice. It is matter for regret that I
cannot see the same localities in June or July when, I believe, this extraordinary
growth of weeds dies down annually.
Nature does not always hold an even balance ; it dips occasionally and only an
intimate acquaintance with the bionomics of the whole assemblage of the local fauna
can enable us to devise effective cultural measures and to guard those deposits of
HORNELL—MARINE RESOURCES 5
economic value from the active aggression of predatory enemies and from the passive
competition of creatures of similar habitat or dietary.
As a result of the information obtained by dredging, diving, and shore-collecting
during the five weeks of the investigation, it appears that the seaward or western
coast of Okhamandal may be eliminated from further consideration. Its aspect,
fronting the terrific onset of the south-west monsoon surf, renders it too exposed to
permit of exploitation from May to September, save for a paltry number of chanks
that may be picked up in the shallows at low tides. The turmoil of the breakers
is too great to permit of existence on the littoral and down to a depth of twelve
to fifteen fathoms save to such quickly growing animals and plants as can spring
into luxuriance in the comparatively quiet interlude afforded by the north-east monsoon
season, or to such others as have so modified their structure and habits as to be
able to withstand the battering of the surf and the wrench of a violent undertow.
Not a trace of pearl oysters, living or dead, was found; not even the smallest
fragment of a valve. From this and the physical circumstances of the locality I
am satisfied that no deposit or bed of pearl oysters has existed here since the
configuration of the adjacent coast assumed its present aspect. Even if they did
exist, it would in practice be impossible to fish them, either by means of the dredge
or by the help of naked divers, the former because of the rough nature of the
bottom—great surf-worn boulders in many places, the latter because in the season
available, winter, chill winds prevail with too low a temperature.
By means of the dredge and occasional diving descents we also went over all
the likely localities in the deeper off-shore waters, notably the great bank named
Gurrur on the Admiralty Chart. This extensive bank which lies five to six miles
west of Okha Point, measures ten miles in length by one and a quarter miles in
breadth, with depths of from six to ten fathoms over it; it slopes rapidly into deeper
water on the landward side as well as on the seaward or western aspect. Judging by
the analogy of the similarity in depth, in distance from the mainland, and in apparent
configuration with some of the large pearl banks in the Gulf of Mannar, I had some
hope of finding here likely biological conditions for pearl oysters. Such hopes were
disappointed ; the bank proved to be an irregular plateau—a flat-topped rocky reef
covered more or less thickly with rolled and water-worn fragments of shells and
small pieces of dead coral. There appeared to be an almost complete dearth of life.
The bank is barren and washed by continual currents that keep the bottom in a
constant flux and reflux. The day devoted to its examination (December 22nd) was
comparatively fine, and even then the launch drifted at quite four knots an hour,
while the divers reported such a strong bottom-current as to render it almost
impossible to keep a position on the bottom for even a few seconds. With a light
north-east wind and calm sea the water on the bank was distinctly muddy and in
contrast to the brighter water beyond its margin, so that evén without resort to
6 OKHAMANDAL MARINE ZOOLOGY REPORT
the lead we could tell the moment we arrived on this bank. As_pearl-oyster
ground the Gurrur is hopeless—a battle-field of tide and current.
On the northern aspect of Okhamandal more favourable conditions prevail, as the
shore-line and the shallows there are in a large measure protected from the violence
both of the south-west and north-east monsoons. Especially is this the case with
the great bight formed by the deep horseshoe curve of what may be termed Beyt
Harbour, using the name in a widely comprehensive manner. This bay or harbour
has as its two horns, Yamiani Point and Samiani Island on the west, and Poshetra
Point on the east, with the long, irregular mass of Beyt Island lying athwart the
entrance, and sending irregular promontories so far within the bay itself as to reduce
the latter to little more than a reef-choked, rather wide channel between the island
and the mainland. Through this passage, Beyt Harbour, a strong tide-race runs,
bearing food matter in profusion to every corner of the littoral. The rocky reefs
and islets that crowd the western and south-western sections set up an intricate
network of cross currents and eddies, ever changing with the phase of the tide, and
aiding powerfully in the distribution of the planktonic food supply. Never have I
seen a richer and more diversified fauna within such a limited area. Within
a distance of eight miles the faunal association changes completely full half a
dozen times. On the rocky littoral of Adatra, we have a profusion of massive
corals, sponges, and aleyonarians; half a mile on we reach the Zostera and Halophila
prairies of Aramra with muddy flats supporting the edible oyster in profusion.
Another two miles and the muddy rocky littoral of Kiu reveals at low tide
the strangest forest in miniature we could imagine. Over several acres of the
lowest zone of the littoral uncovered at the greater spring tides, myriads of the
short-branched parchment tubes of the polychet worm Hunice tubifea rear their
stalks above the surface to a height of eight to ten inches. Plate IIL. is a view of
a portion of this strangely covered ground, a scene unique in the whole of my
experience. Dense tufts and tassels of long-branched, elegant Bryozoa drape and
smother from view many of the tubes, the stalks and branches further clothed with
many-coloured crusting species of sponges and tunicates.
Move but a short distance seawards to the deeper water of the channel, and the
dredge brings up great scarlet and orange-coloured sea-fans (Gorgonids) and the whips
of the related Juncella, together with a variety of sea-urchins and starfishes. Still
another short move to the muddy Bay of Balapur on the cast side of Beyt Island
and we come across multitudes of mud-dwellers of forms totally distinct from those
of Aramra and Kiu, for we discovered here what appeared to be an extensive bed
of window-pane oysters (Placwna placenta) and great quantities of a fine species
of the brachiopod Lingula. On the sands at higher level on the littoral, great
numbers of a burrowing Nemertine worm were met with, speckled on the dorsum to
* See illustrations to the Report on the Aleyonaria,
MARINE ZOOLOGY OF OKHAMANDAL MARINE INDUSTRIES, PLATE II
Photo by Vividha Kala Mandir, Baroda.) [To face p. 6.
A Memory of Samiani Island.
The pames from left to right are :—
Upper Row: Dewan Bahadar VY. M. Samarth and My. Hornell.
Lower Row: Ma. K. B. Pradhan, Vahivatdar of Dwarka; My. Sunderial, Executive
Engineer, and Rao Bahadur Dr. k. V. Dhurandhar, Sanitary Commissioner
of Baroda State.
HORNELL—MARINE RESOURCES 7
match the coloration of its habitat, while at the junction of the muddy bottom
with the sand and gravel of the higher zone at the north end of the bay, a giant
anemone, Discosoma sp., was plentiful (Plate VIIL), together with a magnificent
yellow species of the alcyonarian Dendronephthya | :
a cauliflower-like creature nearly
related to the red coral of commerce, Even this does not exhaust the faunal variety
Fic. 2.—Lingula from Balapur Bay, showing the
proportionate length of the muscular “ stalk.”
of the district—the flat-topped, surf-harried reef islets have their own distinctive
animal associations—mostly free-moving creatures that know how and where to find
refuge from the force of the breakers when heavy seas pound the reefs. Of such
are crabs, crawfish and other crustaceans in fair variety and several species of octopus.
Anemones allied to Tealia and Sagartia are numerous but inconspicuous, while
beneath boulders a considerable diversity of molluscs, tunicates, worms, and fishes find
refuge.
8 OKHAMANDAL MARINE ZOOLOGY REPORT
It was in clefts and under boulders near low-tide level around the margins of
these reefs that we found the only pearl oysters (M. vulgaris) obtained during the
investigation.
All the above mentioned localities received sufficient attention to permit their
economic potentialities to be gauged; the faunistic results are given in detail in
the “Narrative” of the work printed on other pages—we may therefore proceed
now to a statement of the facts ascertained concerning economic questions and the
conclusions derived therefrom, and then discuss in detail those which hold out any
promise of successful development. We will treat the conclusions under the heads
of pearl oysters, window-pane oysters, edible oysters, chanks and chank-fishing,
and, lastly, sea-fishing and fish-curing.
PEARL OYSTERS.
That Pearl Oysters (Margaritifera sp.) exist on the coast of Okhamandal was
well known prior to this inquiry, and several attempts had been made previously
to ascertain if the establishment of a pearl fishery in the neighbourhood of Beyt be
practicable. As the merchants of Dwarka transact considerable business with the
ports of the Persian Gulf and the western shores of the Arabian Sea, the Okha-
mandal coast is frequented by Arab traders and by trading craft engaged in the export
from Dwarka and Beyt of salt and of earthenware utensils. Many Arab sailors engage
in pearl-fishing in the Gulf during the south-west monsoon and on several occasions
some of these men have expressed the opinion that the Okhamandal coast is fitted
for the establishment of a pearl fishery. What they meant was undoubtedly that
the physical features of the shore, the depth of the water, and the general
character of such seaweeds and animals that would come under their observation
on the littoral and in the shallows are such as they associate in their minds with
good pearling grounds in the Persian Gulf. Some Arabs are stated even to have
averred that the west coast of Okhamandal “abounds with pearl oysters, especially
to the west of the villages of Bhimrana and Mojab.”* Another reason which favoured
the presumption that a pearl fishery might be worked on this coast was the fact
that further to the eastward along the southern shore of the Gulf of Kutch and
within the limits of the State of Nawanagar or Jamnagar, pearl oysters yielding
pearls of good quality are fished in considerable numbers. This pearl fishery is
carried on under the control of the government of the Jam Sahib of Nawanagar ;
it has been known and famous for many years, and Mr. Samarth mentions that of
so much account was it in the days of the Emperor Aurangzeb, that Nawanagar
was made Khalsa Sarkar under the name of Islampur, the Jam being continued
' These facts are derived from a report by Mr, Samarth, the Sar Subha of Baroda, kindly
communicated to me.
HORNELL—MARINE RESOURCES 9
as ruler. ‘And the Jam forbore to work these fisheries for fear, lest if their
great value should be known to the Emperor, his territory might be permanently
confiscated ” !
That some of the best of the Jamnagar pearl-fishing ground is situated on
tide-washed reefs a few miles to the east of Beyt was a fact holding out distinct
promise to the Okhamandal officials ; accordingly, the services of two Arab divers were
secured for two months in the autumn of 1894 (about October), but without. any
success, the season being stated to be unfavourable.
Subsequently two Nawanagar pearl fishers who had settled in Dwarka were
induced to make a fresh attempt. ‘They did succeed in finding some pearl oysters,
and from these about seventy-nine pearls were obtained, of an aggregate value of
Rs. 58-11-0. Three other pearls were found about the same time, one of which was
valued at Rs. 30, the others at 8 annas and 6 pies respectively. They were of the
same general quality as the average of those fished in Jamnagar. ‘This particular
attempt was then abandoned, as it was considered undesirable at that stage to
spend more money on investigation, principally on account of the great difficulty
experienced in obtaining men having suitable knowledge of the work.
In view of this obstacle to local effort, I was desired by the Baroda Government to
engage in Ceylon a small staff of divers to accompany me to Dwarka and take part in
the work of inspection. I therefore took with me three of the best Tamil divers I was
acquainted with, men capable of diving and working at a depth of ten fathoms, and as
far as possible we utilised their services on every suitable occasion. Unfortunately, the
only season when the western coast of Okhamandal can be examined is during the cold
season, when the north-east monsoon is on; as a consequence the temperature of the
sea was low, and the discomfort of this to naked divers was so intensified by chilly
winds that the time devoted to diving was much curtailed on many days. A
combination of diving, dredging, and wading at low water proved sufficient to provide
the necessary data to enable us to settle the question at issue definitely and finally.
The facts ascertained regarding the different sections of the coast may be sum-
marised as follows :—
Western Coast.—No living pearl oysters were found anywhere along the western
coast of Okhamandal, neither were there found any dead shells—not even the veriest
scrap of one.
Right along this shore, from Dwarka northwards to Okha Point, unmistakable
signs were everywhere manifest of the great force and violence of wave-action
experienced during the south-west monsoon. Just north of Dwarka headland the tidal
or littoral plateau is of great width and remarkably level. Even a tyro can sec how
the plateau owes its origin to the undermining and disintegrating action of the heavy
rollers which at high tide during the monsoon break at the base of the cliffs with terrific
force. The sea is gradually eating into the land all along this coast, forming a wide
10 OKHAMANDAL MARINE ZOOLOGY REPORT
tide-washed fringing plateau wherever the sea is margined by hard strata. (Plates III.
and V.)
The dearth of life over this littoral plateau is extraordinary ; nowhere else have I
seen so bare an expanse of sea-washed rock. Scarcely a limpet is to be found, and
seaweeds are few and inconspicuous. Only here and there in a pool exceptionally
well protected do some forms of life flourish. (Plate VI.)
Beyond low-tide level, along the rocky portions of the coast, the littoral is
margined by a considerable width of sea-worn, rounded boulders, torn originally from the
coast cliffs, and rolled about on the littoral plateau till at last they have found their
way to a depth where they suffer little disturbance. Among these boulders I found
considerable wealth of life at the time of my visit (December-January), when they were
swathed in a dense growth of seaweeds of several species. I was told that towards or
at the onset of the south-west monsoon, this growth dies down. Anyway, with weed
of such density it is a practical impossibility for divers to exercise selection in what
they pick up, and to find oysters—even if they were there—is not possible. It would
be even as looking for a needle in the proverbial bundle of straw. Besides this, work
by naked divers during the winter season is not commercially practicable on account of
the coldness of air and water—the air more especially, as the men feel the chilliness of
the air most acutely during the intervals between diving. Even lusty Arabs will not
face the hardships of pearl-diving in the winter season in the Persian Gulf; so we may
at once rule out the possibility of carrying on a fishery by means of naked divers on
the west coast of Okha during the cold months of the north-east monsoon. The
violence of the sea during the rest of the year—the warm months when pearling goes
on merrily in the quieter waters of the Persian Gulf—with even greater force precludes
pearl-fishing operations on the ocean coast of Okha at that season.
With naked divers ruled out, the only alternatives, and those too, available
only during the north-east monsoon, are fishing by mechanical means (dredging), and
by divers with diving suits and pumps. Neither is feasible, the former by reason of
the unevenness of the ground, and the latter partly for the same reason, and partly
because of the smothering growth of seaweeds.
I am satisfied that if oysters did exist in quantity on this rough and uneven
bottom, very great difficulties would be experienced in fishing them. I am, however,
equally satisfied that pearl oysters do not and cannot exist in this particular locality in
any number sufficient to make them worth a search. The bottom is too rugged to suit
pearl oysters, which, except in such an unusual instance as the sheltered Jamnagar
reefs, require fairly level bottom if we hope to find them in really paying quantities,
a.é, in aggregated masses or ‘‘beds,” in contradistinction to the isolated habit
characteristic of the Kutch or Jamnagar pearl oysters. (Mote——As will be seen further
on, the Kutch pearl oyster is the same species as that of Ceylon, being the small thin-
shelled Margaritifera vulgaris, which is normally or typically gregarious.)
HORNELL—MARINE RESOURCES 11
NortTHern Coast.—As already noticed, the shore of Okhamandal washed by
the Gulf of Kutch is much more varied in physical and faunistic characters than
is the western or ocean coast. According to the different physical features of the
littoral, we may conveniently treat the various sections under heads, as follows :—
(a) Adatra coast facing Beyt Island,
(b) The steep western and southern shores of Beyt Island,
(c) The rocky islets in Beyt Harbour,
(da) Avamra and Kiu shores,
(e) Balapur and Rann Bays,
(f) Flat-surfaced reefs submerged at high tide—Chindi, Hanuman Dandi,
Mangunda, Borio, &c.
5D y ri
Sy
‘
Fic. 3.—Types of Porites coral growth, Adatra littoral.
(a) Adatra.—This locality is that part of the Okha peninsula north of Aramra
Creek. It is a low-lying tableland of gritty coral limestone. From a point opposite
the town of Beyt and thence southwards towards Aramra Creek, the eastern side
is fringed with an extensive stretch of reef-like littoral gradually sloping to extreme
low-water mark. The tide-race through the narrow channel of Beyt Harbour furnishes
ample supply of food particles, and as this end of the harbour is kept free from mud
12 OKHAMANDAL MARINE ZOOLOGY REPORT
the flat littoral of Adatra is very rich in organisms that love the rush and swirl
of tides and highly oxygenated water. Massive corals (Porites, Turbinaria, and
astreids) and great fleshy alcyonarians (Sarcophyton) flourish in great luxuriance
and, strange to say, bear occasional exposure to the air without ill consequences
at the times of great spring tides. Madrepores (branched corals) were conspicuous
by their absence. Little weed grew here except near low-tide level, and several
dead shells of fully grown pearl oysters (M. vulgaris) were found. The Vahivatdar
was also able to assure me that live oysters have been found here to his knowledge.
Certainly the place is quite suited to give them foothold, but as the reef slopes
off rapidly from low-water level into the deep, gravelly channel of the harbour,
and as the range of pearl oysters does not extend far above low tide, the reef at
best can support them only in extremely limited number.
(b) North and south of the town of Beyt and also along the south coast
of the island, the land rises abruptly from the sea into cliffs of fifty to sixty feet
in height. The sea bottom along these cliffs is very uneven and is not suitable
for the growth of oysters. In many places there is a great tangle of sea-fans
and sea-whips (Gorgonids), while the current on the bottom is usually very strong.
Every time we used the dredge we had trouble; it was continually fouling some
obstruction so that even if there are pearl oysters here (we saw not a trace
of any) they could not be fished save by pump divers, at a cost which would
be prohibitive.
(c) The rocky islets and small reefs in Beyt Harbour.—On some of these,
as for example the Dhed Mora, occasional pearl-oyster spat may settle in the zone
near low water. At the season when I was there, seaweed growth was so rank
at this and the next lower horizons that it was impossible to search effectively
for stray individuals. Had oysters been present in any fishable quantity—in any
number adequate to make fishing remunerative—the search was sufficiently effective
to have revealed some. The nature of the ground, boulders of all sizes piled up
round the bases of these rocky islets, is quite against the presence of any fair quantity
under the best conditions of spat-fall and immunity from enemies.
(d) Aramra and Kiu.—As mentioned incidentally once before, these localities
are covered in the main with a varying thickness of soft mud. Pearl oysters cannot
possibly exist there, though in the higher portions of Aramra Creek there is a
“hard” which is well suited to the cultivation of the edible oyster. Of this more
will be said on another page.
(e) Balapur and Rann Bays.—The bottom in these bays is a uniform
expanse of flat mud tenanted by beds of window-pane oysters, by Lingula, a
suberitid sponge and other lovers of the mud. These localities share the disabilities
of Aramra and Kiu.
HORNELL—MARINE RESOURCES 13
(f) The flat-surfaced reefs.—The principal of these consist of Chindi, Borio,
and Mangunda, the first due north of Beyt Island, the two latter east of Poshetra.
Hanuman Dandi may also be grouped here, albeit it differs in being still in physical
connection with Beyt Island.
The following particulars of Borio and Mangunda taken from the rough field
notes made on the spot will indicate the physical and faunistic features common
within close limits to the majority of the reefs which are dotted along the southern
shore of the Gulf of Kutch for a considerable distance eastward of Okha Point and
Beyt.
Borio reef or kharaba was found to resemble the eastern or more sheltered
portion of Chindi reef fairly closely, but animal life on Borio is much richer and
more diversified. A raised gravel bank on one edge of these reefs is a characteristic
feature and seldom or never wanting. At Chindi such a bank is found on the
south side, but on Borio and the neighbouring Mangunda it has a north-east aspect,
a difference due to the set of the tide, which runs very strong between these
reefs,
The surface of Borio is nearly dead level, and represents a plane of marine
denudation, the sea having cut its way entirely across the original islet, so that no
point remains unsubmerged at high tide.
In shallow hollows at the north-east end were many finely grown corals,
massive Porites, dome-topped astreids, a thin brittle species, and some others, a
greater diversity than anything before seen in the district.
The higher level, say six to nine inches above these pools, is gravelly, made
up largely of worn fragments of madrepore branches, with immense quantities of
Vermetus, a strange mollusc forming sinuous calcareous tubes attached to the
pebbles. A drab-yellow anemone (Tealsa sp.) lives here in profusion with a few
of another anemone, the giant Discosoma, characterised by a multitude of tiny
knobbed tentacles set like velvet pile over the widely spread disc (Plate VIII. fig. 1).
In the shallows the same anemones occur, together with a third with column well
sunk in the gravel, and not unlike a Sagartia but with short pinnate processes on the
tentacles. Several of the large wedge-shaped bivalve Pinna were .found here, and
also the complete shell of a pearl oyster of the same species as that of Ceylon
(M. vulgaris), and fragments of others. The complete shell belonged to an
individual apparently recently dead and aged about two and a half years. A
fragment of another shell was picked up close by.
Several octopus—well-known enemies of bivalves such as the pearl oyster—
were seen, and are, I fear, fairly common.
On the north-east fringe of the reef few alge were seen; on the south side they
were abundant, making the search for pearl oysters very difficult. A large number
14 OKHAMANDAL MARINE ZOOLOGY REPORT
of loose blocks of dead coral are present along the southern portion of Borio and
these give shelter to numbers of crabs, small fishes, and crusting sponges. Large
zoanthids were not uncommon associated with large fleshy aleyonarians (Sarcophyton).
The formation of Mangunda reef was found very much like that of Borio,
rich loeally in corals, anemones, octopus, and, at extreme low water, fine colonies
of a cauliflower-like pale orange Dendronephthya (D. brevirand).
On the higher level in the centre of the reef, the small coral fragments
forming the surface are infested with Vermetus tubes and with multitudes of
brood edible oysters (Ostrea) whose sharp edges make walking barefoot most
dangerous.
In the shallows towards Borio, a profusion of red alge of several species
was present.
Fic. 4.—Inner and outer view of the valves of a Pearl Oyster (Jf. vulgaris)
from the Gulf of Kutch.
It was on Manegunda that we at last found the pearl oyster alive—a single
individual at extreme low water attached to the overhanging side of a boulder.
It was about eighteen months old, very fat and in an excellent condition of health.
Besides this not less than ten dead shells were found of an age, when living,
of from one and a half to five years. All were of the Ceylon species, and as the
other live and dead oysters found at Pagar Kada and Adatra were similar, it would
seem that the Kutch pearl oysters all belong to M. vulgaris.
On another day a visit was paid to Pagar Kada, a reef of much greater size
than either Borio or Mangunda. In many respects it is a reef of special interest
for the reason that on account of its large area some parts of the central region
have peculiar physical characteristics. These, however, need not be particularised
here, as our examination of this reef confirmed the conclusion come to from a
study of Borio and Mangunda, that the habitat of pearl oysters in these waters
HORNELL—MARINE RESOURCES 15
is limited to the peripheral region—to that zone which is uncovered, and then
only partially, at the times of exceptionally great spring tides—tides which occur
but seldom in the course of each year. This zone forming the pearl oyster habitat
is the equivalent of the European laminarian zone. On Pagar Kada we saw
evidence of the presence of pearl oysters in this zone in greater numbers than
on any other reef examined, both in regard to living individuals and dead shells.
Unfortunately, Pagar Kada, although geographically belonging to Okhamandal, is
claimed by Jamnagar on the ground of prescriptive rights (pearl fishery rights
I presume they are), and the Courts have decided in favour of this contention.
Summing up the facts ascertained regarding the conditions under which pearl
oysters live in this district, we find that they occur solely in that zone which
marks the low-tide seaward fringe of the shore reefs of Adatra, Poshetra, Hanuman
Dandi, of the isolated reefs of Chindi, Borio and Mangunda, all submerged at
high tide, and of the rocky islets in Beyt Harbour.
The most valuable of these (if we can use such an expression when the oysters
occur so sparsely) are the reefs of Borio, Mangunda, and Adatra; Chindi and Hanuman
Dandi appear less favourable as the habitat of pearl oysters.
Now comes the consideration as to whether anything can be done to establish a
remunerative oyster fishery in the district. We see that pearl oysters do live there
naturally, and that they thrive and even produce pearls—one of the three found by us
contained a fair-sized pearl. We know, too, that a small pearl fishery has existed on the
co-terminous coast of Jamnagar, where similar natural conditions prevail ; therefore
it will be useful at this point to see how this fishery is being carried on at the present
day, and to see if it has further light to throw on our own problem.
The rules laid down for the conduct of the Jamnagar fishery show the industry to
be one of great antiquity, and one regulated by rules as quaint as they are unique.
The essential points are as follows :—
(a) The fishery is carried on under Government control and supervision as a
monopoly of the State.
(b) The pearl fishers are not paid in wages for their labour, receiving instead a
specified proportion of the value of the pearls they may find, partly in cash, partly
in kind.
(c) All pearl fishers are licensed by families, and no one may obtain these licences
except fishermen of specified villages. (Note.—This gives the shore-dwelling villagers
a direct and hereditary interest in the fishery, and is a regulation so excellent that
it might with advantage be adopted in modified form elsewhere.)
(d) The pearl fishery season is limited to the hot weather season, beginning in
June. It is not carried on daily, but only on the dates of the greater spring tides,
when the lowest levels of the littoral may be expected to be uncovered at low tide.
16 OKHAMANDAL MARINE ZOOLOGY REPORT
(ec) Before that date a day for the issue of licences is appointed, those men who
are registered as pearl fishers in ten shore villages being alone notified.
(f) The licensees then form themselves into fishing groups or parties, and are
allotted one or more supervising officers of the State, according to the number forming
the party. A Wagher patel has also to accompany each party.
(g) Pearl fisher parties may fish anywhere they choose, but the members of each
party must keep together that supervision may be efficient.
(h) On the days selected for pearl-fishing the fishers assemble at the house of
their supervising officer, who then accompanies them. They pursue the fishing by
wading. When necessary to use boats to reach the fishing grounds these are provided
free by the chief customs officer.
(:) At the end of each day’s work all oysters collected have to be opened in the
presence of an official, who notes the number of pearls obtained by each fisherman,
and provides him with a numbered cloth in which to wrap them. These little bags
are then dropped into a sealed box, where they accumulate till the end of the fishery.
(j) With the close of the season all boxes are conveyed to the Jamnagar Treasury
where they are opened and the bags belonging to each fisher sorted out from the
others and their contents valued by experts.
(k) Finally each man receives } the value of his catch in cash, #5 in cloth,
and 5 (already received) in food, while two prizes are given to the two villages pro-
ducing the most valuable collections of pearls.
From the foregoing and from the knowledge acquired during the examination
of the Beyt and Poshetra reefs, we see that at its best, along the lengthy sea frontage
of Jamnagar, off which lie numbers of productive reefs of much greater circuit than
any within the limits of Okhamandal, the pearl fishery of the Gulf of Kutch is what
may be termed a village industry. No beds of oysters occur anywhere within
the district. The oysters occur sparsely, scattered singly along a narrow fringe
bordering the reefs and accessible only on the dates of great spring tides during the
warm period from June to September—a very limited fishing season.
In view of these difficult conditions, I do not think the method of actual fishing
pursued can be improved greatly, as several practical obstacles preclude the employ-
ment of naked divers—chiefly the difficulty and excessive labour that are involved
in making a search under water for oysters so sparsely scattered as they are here;
the great force of the currents along the margins of the reefs also stands in the way
of successful diving (my divers complained greatly of this and often said they
could not keep their feet on the bottom). The employment of pump divers is even
less feasible ; the cost would be quite disproportionate to the returns, more especially
as the mother-of-pearl of the shells is of very low value.
HORNELL—MARINE RESOURCES 17
But while a village industry in pearl-fishing is moderately successful in Jamnagar,
there is no possibility of introducing similar methods in Okhamandal, because the
suitable shore-line there is far too restricted to furnish more than a few dozen oysters
even if large numbers of men be employed on all available days. It is not as though
the whole shore-line is of oyster-bearing value; much more than half is unsuitable.
Nature unaided fails us in this matter; it may be then asked whether science
cannot help—whether some form of culture might not be successfully introduced.
Reluctantly I must answer in the negative so far as present methods go. In the
case of M. vulgaris, the small pearl oyster living there, the shell is of such little
value, so thin and convex, that it is fished for the pearls that may be contained and
not for its shell. But pearl-bearers form always so very small a proportion of the
catch that if we were to cultivate them in cases or otherwise we should find so many
unproductive of pearls that the expenses of spat-collection, supervision, and upkeep
would entail certain failure under such conditions as we have around Beyt. Were
there beds of natural spat available for transplantation in the neighbourhood, the
attempt indeed might be made, not otherwise.
Were we able, however, to control and induce the production of fine quality
pearls in any given oysters—I do not refer to the imperfect or attached pearls
produced in Japanese oysters on the lines of the ancient Chinese plan—then it
might be practicable to carry on such special culture at several localities in
Beyt Harbour, seeing that the strong tides experienced there are favourable to
the rapid growth and maturing of the oysters laid down there. But such a proposition
is one requiring a combination of skill and organisation not at present available
and would be a commercial enterprise unsuitable for a Government to undertake.
The most that I can suggest is that for the present the collection of pearl
oysters be leased out, if possible in conjunction with that of chanks—that is, that
one lease should cover both products, because if they were leased separately
there would probably be friction between the respective renters; the chank renter
and the pearl oyster renter would naturally fear invasion of their respective rights.
As to restrictive regulations if this proposal be acted upon, I do not consider the
enactment of a size limit is practicable or would be of any value. But the reservation
in rotation of different sections of the coast for stated periods during which all
fishing therein for pearl oysters and chanks shall be forbidden, is buth feasible
and likely to result in material benefit to both fisheries.
Under the heading of “Summary of Recommendations” I shall take up this
proposition in detail.
18 OKHAMANDAL MARINE ZOOLOGY REPORT
CHANK-FISHING.
The chank or shank (Turbinella pyrum) is a shell as characteristic historically
of Okhamandal as the pearl oyster is of Jamnagar, and although neither this nor
the sections dealing with other marine products which follow come within the
terms of reference of my investigation, | trust that the following notes of what
I learned and the impressions received will be approved and prove useful.
Fia. 5.—An adult chank from the Adatra reefs, Beyt Harbour, — X 5.
At many places along the coast from Dwarka to Beyt the chank occurs in
sufficient abundance to make chank-fishing a small local industry. Since Samvat
1918 (a.p. 1861) the monopoly of the fishery has vested in the Baroda Government.
Till s.p. 1893 the authorities combined two systems of administration, renting
out to the highest bidder the chank fishery in the Island of Beyt, while the chank
beds of the mainland (Avamra and Meeta Bundar) were worked by individually
licensed fishermen, who paid Rs. 3 each for the privilege. Since the date
HORNELL—MARINE RESOURCES 19
named the lease of the whole fishery, mainland as well as insular, has been put
up to tender, and is now fished by men either employed directly by the renter
or under sub-licence from him. The renter is the only person in the district entitled
to vend chanks, and the places where sale may take place are limited to three—
Beyt, Aramra and Gopi.
The annual revenue to Government for the eight years following their assumption
of fishery control was respectively as follows, viz. :—
Samvat 1918 and 1919 ... .. Rs. 191 10 8
Ss 1920 vais ae aie 55 0 0
a 1921 ee a Sy 20 0 0
ra 1922 ae ats ey 5 0 0
3 1923 ee ey a8 65 0 0
3 1924 sis a sae 90 0 0
3 1925 ae wuss — 110 0 0
Total for 8 years ... .. Rs. 586,,10 ,, 8
an average of say Rs. 67 per annum.
Comparing this with recent results, we find that the rentals at which the fishery
as a whole was leased out during the ten years ending 1906 were as follows :—
1896-1897 ies aid tae Ne Rs. 96 0 0
1897-1898 ian sa sais Bath 160 0 O
1898-1899 Ae on roe ie 160 0 0O
1899-1900 3 das are shes 97 0 0
1900-1901 ae sas bees eh 81 4 0
1901-1902
to five years att sue 755 0 0
1905-1906 —
A total for 10 years of ... Rs. 1349,,4,,0
which gives an average of Rs. 1834-14-10 per annum, a sum comparing very
favourably with that obtained at the beginning of Government administration.
It would be interesting and useful to learn if this rise im the value of the fishery
is due to increase in the numbers caught, or whether to a rise in price. There appear
to be no data on the subject, as the lessee, who alone could furnish them, can hardly be
expected to supply such a return. I am inclined to the opinion that the cause is more
likely to be due to increase in the selling price, seeing that the customers for this
strange article of commerce are confined to Hindu pilgrims visiting the holy places
of Beyt and Dwarka, who have largely increased of recent years since regular steam
communication was established between Dwarka and the ports of Sind, Kutch,
c 2
20 OKHAMANDAL MARINE ZOOLOGY REPORT
Kattiawar, and Bombay ; the opening of a railway to Nawanagar, only some fifty miles
distant, has also had a favourable influence in causing an increase in the pilgrim trafiic,
and this in turn has probably entailed a rise in the retail value of the chanks
purchased as charms and holy souvenirs of a memorable pilgrimage.
We come now to a consideration of whether it is necessary or desirable to take
any steps to safeguard the well-being of this industry, and whether it is possible to
do anything to render it more productive.
In the first place we have to recognise the great limitation of the area where
the fishery is carried on. The habitat of the chank is a peculiar sandy bottom
known to the Tamil chank fishers of the Gulf of Mannar as puchcha manal or
“insect-sand,” containing such an amount of mud and organic matter as forms it
a suitable home for the sea-worms whereon the chanks feed. This haunt of the
chank is found at comparatively few places on the Okhamandal coast, the principal
being the sandy shore north of Kutchegad, the sands of Soso Bhara (esteemed the
best on the west coast), the bay between Okha and Vamiani Points, the coast of
Adatra facing Beyt Island, and Hanuman Dandi at the north of Beyt Island. A
few are also taken on a part of Chindi reef and on some of the banks in Beyt
Harbour; some also at Borio and Mangunda. All told the chank grounds suffer
from the unalterable disadvantage of possessing extremely limited area. which in all
probability cannot support any large increase in the number of chanks living
thereon. As no considerable increase in the revenue can be hoped for on account
of this limiting factor, any measures to be taken must be equally limited financially.
If we turn to the great chank fishery of South India, we find that the
sole limitation imposed by the authorities on the fishermen, is that they shall
return to the sea any chank found that will pass through a gauge hole having a
diameter of two and three-eighths inches, and this is a rule which, if adopted in
the Okhamandal fishery, in my opinion would tend to benefit the industry, as it
would help to conserve the chanks till they reach maturity and have an oppor-
tunity to breed and raise up seed unto themselves. It would go far to counteract
any possible ill-effects arising from overfishing, which the payment of a high rental
and a brisk demand for the shells is bound to induce. Such latter factors are, I
fear, likely to result eventually in a more or less severe depletion of the beds. Of
course, the selling of undersized or immature chanks would also have to be made
a punishable offence. So I recommend the partial protection of chanks when next
the fishery be leased by the insertion of a condition (with proper penalties for
infraction) that no chanks be fished less than two and a quarter inches in diameter
and that gauges of this size be kept by the local officials at the fishery and sale
villages. If enacted, it must be impressed on the fishermen that these undersized
shells be returned to the sea near the chank bed as soon as possible after the close
of the day’s fishing—we cannot expect each man to carry a gauge with him, and
HORNELL—MARINE RESOURCES 21
probably it will be found convenient to defer the measuring till the men gather
together at the end of the day.
It will be noted that I suggest a smaller gauge than that in use in South India ;
it is better to err on the lenient side till further experience be obtained. The
benefit to be derived from this procedure should be clearly explained to the men in
order to gain their goodwill in carrying out the regulation.
Close Scason.-—If a size limit as above be enforced, no special close season need be
enacted, as the fact that fishing can be carried on with advantage only on the dates of
the great spring tides constitutes a natural close time sufficiently protective to require
Fics. 6 and 7.—Half-grown chanks (Zurbinella pyrum) from Adatra reefs, Beyt Harbour.
no artificial extension. It may, however, be useful to close the different sections of the
coast in rotation for limited periods.
Culture.—Any form of culture necessarily demands the attention of an ofticer
with at least an elementary training in fishery science on the culture side. Current
conditions preclude, I fear, the provision of such an officer ; but as there is a likelihood
in the near future that opportunities may be available for natives of India to receive
training at Government fishery stations on the Madras coast, I propose to suggest how,
a
co)
at small expense, were the necessary oversight provided, simple cultural methods may
be tried with a view to increase the yield of chanks and prevent any fear of a depletion
of the beds.
22 OKHAMANDAL MARINE ZOOLOGY REPORT
I would propose that advantage be taken of the fact that the female chank
deposits her ova in large capsules six to ten inches long, formed of a tough, parchment-
like substance and having the form of a twisted and corrugated ram’s horn. They are
unmistakable when once seen, and are internally divided by a series of transverse
(horizontal) walls agreeing with the number of grooves on the exterior. In the com-
partments thus formed eight to ten young chanks develop from eggs. They remain to
quite an advanced stage within the capsule, breaking out only when they approach a
length of about half an inch. The larger capsules may contain a total of 150 to 230
young of a size fit to begin a free life.
If operations be decided upon, means should be taken, by reward or otherwise, to
obtain a number of these capsules and transfer them to a small pound or enclosure near
low-water limit and on a bottom of suitable chank sand. Here they would be kept till
the young chanks escape from the capsule, when they may be allowed to wander freely
within the enclosure in search of food. Care would have to be taken that the netting
or palisading of the pound be fine enough to prevent the young chanks making their
way out. It would also be desirable to provide some shelter, in the shape of seaweeds,
within the pound that the young chanks may crawl beneath the fronds if they wish.
Later on, as experience be gained, a further step may be taken by enclosing a number
of mature chanks within the pound with a view to obtaining a regular supply of egg-
capsules. It must be understood, however, that these suggestions are tentative ; no
attempts so far have been made to subject chanks to cultural methods—probably
experience will necessitate considerable modification and elaboration of the operations
suggested. The first point to ascertain will be the spawning-time of chanks on the
Okhamandal coast ; we have no information thereon at present.
EDIBLE OYSTERS.
Two species of Ostrea, the edible oyster, occur in Okhamandal, namely—O. crista-
gall, L. and (probably) O. cucullata, Born. The former, which covers the rocks
near high-water limit at Poshetra Point in vast numbers, is unfortunately of little
economic value on account of its comparatively small size and very irregular growth ;
the second species, as seen in samples from Aramra Creek and from Poshetra Point,
grows to a good size and is of most excellent flavour.
Hitherto the demand and taste for edible oysters in India has been extremely
restricted and usually in local demand only, but may be expected to increase
rapidly when once regular supplies are available, seeing how nutritious and palatable
this mollusc is.
Oyster culture has two important initial advantages—-the ease and low expense
at which it may be carried on, and the endurance shown by oysters during transport ;
live oysters are successfully sent in large quantities from America to Europe headed
Lo
ws
HORNELL—MARINE RESOURCES
up in barrels, and a considerable proportion are laid down in English waters either
to fatten and improve in quality, or to await a better market.
When abundant they may be canned for export or their flesh dried for despatch
to China where there is a laree and steady demand for such and similar delicacies.
The industry in Okhamandal is, however, too limited by restricted area to permit
of the latter uses, which necessitate both a very extensive and very cheap supply. Lf
anything be done, it must be, as at Karachi, in the supply to inland towns of high class
live shellfish. This can be effected only when means of rapid transport be available,
which will come when a railway be built from Aramra to Nawanagar, and when a
fishery expert be available to initiate methods and demonstrate how simple is the
procedure to be followed and, it is hoped, how profitable the results obtainable.
Fig. 8.—Oyster rocks between tide-marks at Poshetra Point. The species is O. erista-yulli.
Aramra Creek is an ideal situation for oyster cultivation. The area is fairly
extensive and is favoured with exceptionally great abundance of suitable oyster food
diatoms and algal spores were profuse in the plankton taken there), suitable bottom
exposed over the whole area at certain spring tides, and lastly, complete protection
from rough seas.
In many ways Aramra Creek has a close resemblance to Brightlingsea Creek in
Essex, famous alike to oyster culturist and yachtsman. The advantages are, however,
with Aramra; the area of hard bottom composed of shingle set in a soft clay or
compact mud, is greater, and forms an admirable “laying ground” requiring little
improvement by cleaning and cultching. It is here that oysters are now found
naturally in fine condition. Others, again, are found towards the head of the
ereek attached to the roots of mangroves lining the banks. It would be a very
24 OKHAMANDAL MARINE ZOOLOGY REPORT
simple operation to plant numbers of stakes in the muddy bottom at the lower end
of the creek, or to lay out piles of suitably coated tiles at the spawning season
(yet to be ascertained) to form spat collectors ; the spat so collected, some months
later would be removed from the stakes or tiles and laid out on prepared (cleaned)
gravelly bottom and left there to mature, the bottom being carefully tended the
while to keep down seaweeds and destroy any enemies of the oyster. Variations
and improvements in details would evolve with experience.
The initial experiments to prove that spat-collection and oyster-laying may be
successfully carried on should be conducted by Government. If satisfactory results
be obtained it is to be hoped that local people would then be induced to come forward
and take up sections of the creek on lease from the Government at a purely nominal
rental till such time as the industry may be established on a remunerative and stable
basis. After that it would be for the administration to decide whether the industry
could bear the payment of actual rent or whether it be more desirable to be satisfied with
an indirect revenue return such as would accrue through the increased employment
provided and the greater prosperity induced in the district by the new industry.
IT may mention here that an extensive and profitable trade was carried on until
recently at Karachi in edible oysters obtained from the Sind coast. Some years ago it
was brought to the notice of the authorities that, owing to the improvident methods of
the oyster fishers, the oyster beds in Karachi and its vicinity were being rapidly
exhausted. To stay the progress of depletion and restore the prosperity of the beds
certain regulations were then adopted for the better control of the industry. These
protective measures appear to have proved unsuitable or insufficient, as the condition of
the beds is now (1908) in an unsatisfactory condition, the beds being practically
depleted. The rules which have thus failed in their object consisted in :—
(1) The observance of a close season from 16th April to Ist October in each year.
(2) The licensing of fishermen engaged in collecting oysters for market.
(3) Prohibition against the removal of oysters less than two inches or more than
six inches in diameter.
(4) Closure of the creeks by compartments to oyster-fishing in rotation for
periods of two years.
THE WINDOW-PANE OYSTER.
This mollusc, Placuna placenta, provides a fishing industry of local importance
in four widely separated localities in eastern seas, to wit, Sind, Ceylon, Borneo and the
Dutch Indies. Pearls of inferior quality are yielded in some quantity, while the flat,
translucent shell itself is used in China and Indo-China and the Philippines as a
substitute for glass in the glazing of windows, whence the popular name. Formerly
HORNELL—MARINE RESOURCES 25
this latter use was employed also in the Portuguese possessions along the west coast of
India, but at the present day the Indian fishery in the creeks of Sind and that near
Trincomalee in Ceylon are pursued solely for the pearls produced. The comparatively
poor quality of these is gauged by the recognised standard market value, Rs. 15 per
tola, which prevails both in Sind and Ceylon. Although the object of a recognised
pearl fishery in Sind since 1837, when beds of window-pane oysters were fished for the
first time by the Mirs of Sind, no official knowledge either of the pearl value of these
shells or indeed of their existence in the Okhamandal district seems to have existed
prior to the recent investigation. My attention was first drawn to the probability of
their presence by seeing a large shell in a natural history collection at the Public
Library in Beyt. Subsequently large numbers of well-grown living individuals were
found towards low-water level in Balapur Bay, while later, quantities of brood and
of half-grown shells were obtained by the dredge and by divers from shallow water, one
to one and a half fathoms, in Rann Bay, a wide muddy indentation in the coast-
line at the north end of the Okha Rann. Enough was seen to demonstrate the presence
of well-stocked beds both in Balapur and Rann Bays. Dissection shows that mature
individuals contain pearls in average abundance, so we are fully justified in believing
that in some years sufficiently large beds of these oysters arrive at maturity to provide a
remunerative fishery if there be present the means for carrying one on. Herein lies the
crux ; either oyster dredges specially adapted for work over soft mud must be employed,
necessitating, too, the use of a shallow draught steam-launch or, preferably, a motor-boat,
or a supply of divers accustomed to diving in shallow water must be obtained. In
some respects the latter plan has considerable advantages—there is no initial capital
expenditure, no heavy costs in upkeep during periods when the boats and gear be
not employed, whereas if some of the villagers on the coast could be induced to
practise diving they would add to their means of livelihood, be of inestimable service in
the fishing of these window-pane oysters when required, and be available for any
under-water work, such as the cleaning of ships’ bottoms and the recovery of coal lost
overboard, should Beyt ever become an important seaport, as Nature surely
intended it to be.
In such shallow water as that of Balapur and Rann Bays, diving in the warm
days from June to August should be an art easily taught to the lads of the shore
villages. If Government encouragement were to be given by the offer of a few prizes
to those who attain a certain proficiency, or by other means which the local officials
may adjudge desirable, the hardier and more enterprising lads might be induced to
give more thought to the sea as a life-calling than they do at present. Such lads, if
they can be taught diving and swimming, would eventually furnish the personnel
necessary should sea-fishing ever be developed to a considerable extent on the Okha
coast. Of this more will be said in the following section.
In neighbouring Sind, the window-pane oyster industry has had a chequered
26 OKHAMANDAL MARINE ZOOLOGY REPORT
history. Some years have been moderately profitable to the lessees, while others have
proved barren. The lean years may occur because of several factors, but it is probable
that the chief cause is to be traced to reckless and wasteful methods of fishing,
especially to the wholesale destruction of immature oysters. In Ceylon I have seen
huge piles of shells, remnants of former fisheries, of which quite a large proportion
were too young to be of any real value. To obtain, say, a few pies worth of pearls a
whole thousand of young oysters are often destroyed, which if left to maturity would
yield pearls ten- and twenty-fold or more in value. This, too, leaves out of account
the fact that such destruction, taking place before full sexual maturity is reached, must
militate most materially against the repopulation of the beds with new generations.
Should the window-pane oyster become the object of a fishery in Okhamandal, I
recommend strongly that a regulation be made and enforced strictly enjoining the
fishermen to put back upon the sea bottom, convex side downwards, all oysters less
than four inches and a half in longest diameter. Very few pearls are present in
oysters under this size, so no material loss will be caused to the fishermen or the
lessee, and a valuable step towards ensuring the continued well-being of the beds
will be effected. No necessity is likely to arise for a long time to establish a breeding
reserve, provided size limit be enforced, as every muddy bay along the coast of
the Gulf of Kutch has its beds of these oysters, capable of restocking the Okha
bays should the stock there become depleted. Until all such bays be the subject of
a similar fishery—a contingency most unlikely—the oysters therein may be looked
upon as constituting natural breeding reserves for the whole neighbourhood.
On account of the chill winds of winter, the season for fishing is indicated
as the warm period from May to September as a maximum; June, July and August
will probably be found the most suitable months for the work. The rest of the
year may be considered as a natural close season.
In Sind and in Ceylon the beds are rented out for periods of three to five
years; if it be possible the same system will probably be found the most suitable
for Okhamandal also, as departmental working is necessarily expensive in the
case of a small and intermittent industry such as this must be under the most
favourable circumstances.
Mr. Pradhan suggested the possibility of utilising the shells in button-making.
This is worthy of attention, but I fear cannot be a success unless some method
of hardening the shell be discovered—the shell is too soft and partakes too much
of the nature of slab mica in its natural condition to withstand abrasion, a
quality button material must possess to command extensive employment. Possibly
permeation by some fluid cement might effect this object. I hope to experiment
on such lines before long.
HORNELL—MARINE RESOURCES 27
SEA-FISHING AND FISH-CURING.
What I trust may prove the most valuable and far-reaching result of my
inquiry was to find that though fishes of valuable food species abound in great
numbers both on the northern and western coasts of Okhamandal no fishing
industry exists. I believe I am correct in saying that not a single fishing boat
nor one fixed engine for trapping fish exists within the territory.
On entering upon my mission the possibility of visiting a long stretch of
varied coast-line, where sea-fishing is non-existent was too improbable to enter
into my thoughts and as this question was not included as a subject of my deputation
I took neither lines nor nets with me; as a consequence [ cannot furnish any
details touching the relative abundance of the more important fishes nor can I say
much as to their species.
What I can state with certainty—facts based almost entirely on notes of the
species caught specially by the Samiani lighthouse-keeper and on a few fishes
caught or seen during the general investigation—is :—
(a) That valuable flat-fishes of the genus Synaptura are to be had in Balapur
Bay on the coast side of Beyt Island. ‘This fish is closely allied to the true sole
and is, I believe, fairly abundant.
(b) That the group of fishes generally termed ‘ Rock-fishes” from the preference
they show to rocky bottom, are very abundant in the western section of Okhamandal.
The Samiani lighthouse-keeper brought in daily a more than ample supply for
our kitchen and from this source I found the following fishes to be among the most
frequent, namely :—
Lutjanus sp., Serranus areolatus (Forsk), Serranus fasciatus (Forsk),
Diagramme sp.
Polynemus sp. and a species of Sciena would also appear to be common in this
district.
(c) Several times when off the coast in the steam-launch, shoals of silvery
fishes were frequently seen covering considerable areas with their closely-packed ranks.
Some appeared to be Clupeoids (herring family); others were undoubtedly of the
mackerel group.
A fact of significant importance is the big export fish trade which I believe exists
along the coast of Sind and the State of Kutch. Even in Ceylon a quantity of the
dried fish sold appears to come from the latter district, a certain quality being known
as Kutch fish.
Considering the variety and luxuriance of the marine fauna and flora of the seas
around Okhamandal, it would be incredible indeed if a large fish trade be not capable
of development, especially when we note that natural salt is produced very extensively
28 OKHAMANDAL MARINE ZOOLOGY REPORT
and cheaply in the district, and that the climate is exceptionally dry. Rain seldom
falls, and while this results in frequent famine and ruin to the agriculturist, the fish-
curer, who lays his prepared fish to dry in the open, has no fault to find with such arid
conditions.
Beyt Harbour is an ideal haven for the location of the headquarters of a fishing
fleet, exploiting on the one hand the long stretches of muddy and gravelly bottom of
the Gulf of Kutch, and on the other the teeming surface waters of the Arabian Sea.
Even now, without the distributing conveniences which a continuation of the railway
from Nawanagar to Aramra will supply, a great deal may be done to lay the foundations
of a most profitable industry. The arid land, pre-eminently dry climate, and super-
abundant natural supply of salt to be had for little above the cost of cartage, makes
the situation of Adatra, facing Beyt town, an ideal place for the salting and curing of
fish on a scale of great magnitude.
The collection of pearl oysters and chanks, the culture of edible oysters and of
window-pane oysters can never attain large proportions in this district under any
possible conditions, owing to the restriction imposed by the limitations of area and
coast-line, but the growth of the industries of sea-fishing and fish-curing have no such
natural restrictions. Their expansion will be concurrent with the energy and capital
of the men who engage in it, and need be limited by commercial considerations alone.
There are and will be difficulties attendant on any efforts made to start a fishing
industry ; one of these may be the fear of hurting the religious susceptibilities of those
multitudes who regard Beyt as a holy city not to be entered by low caste men, not to
be defiled by the spilling of blood or the sale of the flesh of animals. But as Adatra
on the mainland is suggested as the location for the proposed industry any difficulty of
this nature will be minimised.
Incidentally I hazard the suggestion that, if no religious or caste scruples bar the
way, the Vaghers probably would make excellent fishermen—certainly the curing of
fish ashore is well within their capacity. Seeing that they come of a race of freebooters,
men ever ready for a broil or for piracy if it offered, they should have that courage
which the calling of a fisherman demands. If they should ever take to such a life,
then the present suggestion would go far to solve what appears to be a recurrent
industrial problem in Okhamandal in regard to the finding of congenial or satisfactory
employment for this clan, whose old occupation of preying on their neighbours being
ended, seem to have difficulty in finding work that will satisfy what we must consider
to be an instinctive longing for excitement.
An industry of the potential value possessed by sea-fishing has, however, a wider
importance than the provision of a trade to a single clan; the successful carrying
on of a large and profitable trade would do much to ameliorate the periods of distress
aud famine due to continued lack of rain which afflict Okhamandal so frequently.
On the occasion of my visit no adequate rains had fallen for over two years ; no crops
HORNELL—MARINE RESOURCES 29
had been harvested during this period over the country as a whole, the peasantry and
villagers were penniless, and but for the famine relief provided by the Government of
H.H. the Gaekwar, many would have had to face death from starvation.
If a fish trade be established satisfactorily, and if religious scruples can be
overcome, many of these same people under similar conditions may earn fair wages by
participating in one way or another in a fish-curing industry, greatly to their own
benefit as well as to that of their Government.
To turn the possibilities outlined above into actuality, to create and establish
an industry characterised by comparative complexity due to the varied character of
the methods that must necessarily be employed and which require to be directed by
specialised skill and technical knowledge of a high order, is a problem calling for the
most careful thought and preparation. Discredit and failure are bound to ensue if
any attempt at rushing the project be made; the allied operations of catching,
curing and distributing must gradually evolve through the necessarily slow processes
of investigation and development. In Europe or America, where fishing and curing
have attained a state of high development and organisation and where skill and capital
are available whenever there are fair prospects of large profits to be made in the
opening up of new fishing grounds or the inception of a newly-devised industry, such
an undertaking as that now suggested above would certainly be taken in hand by
private enterprise, by some firm already in the trade having the command of the
experience, apparatus and capital needful. In India, for various causes, native enter-
prise is extremely conservative, greatly disinclined to strike out in new lines until such
have been proved by others—by Government or European enterprise—to be capable
of yielding good returns; in other words, initiative is lacking in large measure. In
the present instance the requirements of the case are such as cannot be grappled with
except by initial investigation and subsequent pioneering conducted by Government.
As a commencement, full information must be collected on the methods of fishing and
curing already employed successfully on the neighbouring coasts of Sind and Kutch ;
if possible, by one who is an expert in fishing and curing, in order that he may be
able to assess the advantages and disadvantages of the methods hitherto employed,
and to advise what modifications and innovations should be introduced. The next
step will then be to ascertain what fishes of food value are available in sueh numbers
in the sea around Okhamandal as to be worth fishing for specifically ; in other words,
a fish census will have to be taken by means of such nets, lines, and other means, as the
officer in charge of the investigation may deem most suitable. The most effective
methods of capture will next have to be ascertained by practical experiment, together
with the forms of curing suitable for the markets to be catered for. A modest and
temporary experimental station may be found desirable as the headquarters of the
expert where he may carry out his experiments. Here, too, he would be able to make
a series of demonstrations for the benefit of such of the local men of standing and
30 OKHAMANDAL MARINE ZOOLOGY REPORT
enterprise as may be persuaded to take an interest in the proceedings. The eventual
suecess of the project will in large part depend upon the degree of interest aroused
locally and of co-operation secured from the wealthy trading community, and every
effort would have to be made to enlist their active sympathy.
I suggest the vicinity of Okha Point as the most suitable site if the establishment
of an experimental fishing station be eventually resolved upon.
In conclusion, I trust the time is not distant when we may see*tured fish forming
the chief export of Okhamandal, providing cargoes for regular coasting steamers and a
fleet of buggalows trading with the great fish-consuming centres of India, Ceylon and
Africa ; I hope also to see the day when, rail connection being established between
Beyt and the main railroad system, refrigerating vans may carry the soles and pomfret
of Okhamandal to India’s inland cities.
SUMMARY OF RECOMMENDATIONS.
The following synopsis of recommendations for the improvement and greater
utilisation of the marine resources of Okhamandal may be divided conveniently
into three sections, namely :—
(I) Those suggestions and operations which require no special or expert
knowledge, and which may be put in hand forthwith by the local
authorities, if approved.
(II) Those which necessitate the officer in charge of the operations having had
some moderate degree of special training such as may be procurable, I trust,
before long at the fishery experimental stations now being established by
the Madras Government.
(III) The very important recommendations relating to the establishment of sea-
fisheries and fish-curing operations which must be preceded by a special
local investigation requiring the services of a first-class expert and
organizer.
I shall accordingly take these sections separately, and recapitulate briefly the
recommendations given in detail on the preceding pages.
Section J.—REcoMMENDATIONS REQUIRING NO SPECIALLY-TRAINED SUPERVISION.
A.—The Pearl Oyster Fishery.
(a) The reservation in rotation for stated periods (say of two years) of the
different sections of the coast; during this time all fishing shall be
forbidden in the section proclaimed.
HORNELL—MARINE RESOURCES 31
(b) That the leasing of the right to collect. pearl oysters be offered periodically
im conjunction with the lease of the chank fishery ; that the lease be for a
term of either three or five years.
B.— Window-pane Oysters.
(a) Teach the lads of the coast villages both swimming and diving.
(b) Watch for the occurrence of a large bed of mature oysters, and then
endeavour to lease the fishery of the bed to a Karachi or local contractor.
(c) Stipulate in any lease made, and also by formal proclamation, that no
window-pane oysters under four inches and a half in longest diameter may
be brought ashore under penalty; that any undersized shells which may
be found in the course of fishing be put on one side and relaid on the
bottom convex side downwards, in a specially demarcated area adjacent
or convenient to the fishing ground.
(cd) When once the industry be established, it will be preferable that the lease
of the fishery be for terms of either three or five years, rather than for a
single year, as the former arrangement gives the renter a deeper interest
in the prosperity of the fishery, and also gives him a chance to recoup loss
sustained in a bad initial season.
©.—The Chank Fishery.
(a) The chank-and pearl oyster fisheries to be leased in conjunction whenever
possible, and to be for periods of either three or five years.
(b) That the fishing grounds be divided into four or five sections, as may
be convenient, and that these be closed to fishing in rotation for stated
periods. Thus, if the grounds be divided into the five sections of (1) west
coast, (2) Okha Point district, (3) Adatra shore, (4) islets and banks off
Beyt Harbour, (5) Beyt Island, including Hanuman Dandi and Chindi and
other reefs, each in turn would be forbidden to the lessee for a period of,
say, two years. At the end of this time the section would be reopened to
fishing, and the section next in rotation closed in its turn for a similar
length of time.
(c) All chanks small enough to pass through a circular aperture of two and
a quarter inches diameter, in a gauge made for the purpose, to be returned
alive, under penalty, to the sea at the end of each day’s fishing. To sell,
or offer for sale, such undersized shells to be made an offence punishable by
fine. Gauges to be kept by the local officials at the fishing and sale
villages.
32 OKHAMANDAL MARINE ZOOLOGY REPORT
Section I].—RECOMMENDATIONS REQUIRING TRAINED SUPERVISION.
A.—Chank Culture. If this be resolved upon I recommend :—
(a) That a number of chank egg capsules be obtained, say by reward offered,
and placed in a suitable pound or enclosure, where, after hatching, the
young shall be safeguarded for some weeks till, being of a size better fitted
to enable them to cope with enemies, they be distributed to the principal
chank grounds.
(b) Later on, when further experience be gained, numbers of sexually mature
adults may be impounded with a view to obtain egg capsules more readily,
and in greater numbers.
B.—Culture of Edible Oysters.
When an officer with sufficient training be available, I suggest that he should
be instructed :——
(a) To ascertain the limits of the spatting season, and to determine the factor
which supplies the stimulus necessary to induce emission of the sexual
products; whether this be increase of temperature, as in Europe, or
decreased density of the water consequent upon monsoon floods, as is the
factor in Southern India.
(b) To set spat collectors of different forms in different places in Aramra Creek
at the beginning of the spawning season, and to note the comparative
results with exactitude.
~-(c) When the young oysters thus obtained be of sufficient size, to detach them
: and “lay” them on prepared bottom on the banks of the creek.
(d) To vary the experiments as greatly as possible with a view to ascertain what
procedure gives the best results locally.
Section [I].—SEA-FISHING AND FISH-CURING.
While restrictions of area preclude any great development in the case of all the
preceding marine products, sea-fishing is wholly without such hampering bonds; on
the other hand, as no nucleus of such an industry exists on or around which to build
and develop, a great amount of preliminary investigation and effort is requisite before
practical work on a commercial scale can be attempted. The first requisite is to obtain
a well-trained and level-headed expert hawng practical knowledge of the more
important methods of fishing as practised in other countries. To him should be
entrusted the task of ascertaining :——
(a) All that is worthy of note in the collecting, curing, and distributing of fish
on the neighbouring coast of Sind.
HORNELL—MARINE RESOURCES 33
(6) What marketable fish exist in fishable quantity in the sea within fishing
range of Beyt Harbour.
(c) What will be the best methods of capturing these fish, bearing in view local
circumstances and that it is specially desired that native talent and capital
shall eventually develop the industry. He will have to experiment with
various forms of nets, lines, and, if possible, with pounds and traps—the
latter specially suitable in the shallow waters of Balapur and Rann Bays.
(d) He should also supervise experiments, employing modern methods, in the
_preservation of the fish caught, and should as far as- possible demonstrate
the processes to selected individuals, nominated by the local authorities,
who, it is to be hoped, will eventually be able to take charge of the
practical operations when the time comes for placing the matter on a
commercial basis.
(e) A small experimental station should be erected at a convenient location near
Okha Point. This, however, must necessarily await the appointment. of
the officer to be charged with the conduct of the investigations, and who
will advise what boats, nets, and other: gear will-be requisite.
JAMES HORNELL.
CotomBo, June 25th, 1908.
a
u
°
H.H. The Gaekwar’s steam-launch “ Pat.”
34 OKHAMANDAL MARINE ZOOLOGY REPORT
MARINE RESOURCES OF OKHAMANDAL.
LIST OF FULL-PAGE PLATES.
PLATE
I.—View of the great temple of Dwarka from the south.
IJ.—A memory of Samiani Island.
IIL, fig. 1.—The shore plateau north of Dwarka.
»» 3) 2—Rock-pools on the shore plateau north of Dwarka.
1V.—A colony of Palythoa tuberculosus in a Dwarka rock-pool.
V.—Erosion into knife-edged hollows of a bed of calcareous sandstone at high-tide
level, Dwarka.
VI.—A forest of the tubes of Eunice tubifex, low spring tide, Kiu, Beyt Harbour.
VII.—Sea-fans and spiny Alcyonarians (Dendronephthya) exposed at low tide, Kiu.
VIL, fig. 1.—Dziscosoma, a giant anemone, photographed in full expansion.
» 5, 2,—Hanuman Dandi reef, an example of a well-marked plane of marine
denudation.
MARINE ZOOLOGY OF OKHAMANDAL MARINE INDUSTRIES, PLATE Ill
Fig. 1.—The Shore Plateau north of Dwarka headland.
(The view is taken looking southwards.)
[Photos by Vividha Kala Mandir, Baroda.
Fig. 2.—Low-tide pools on the Shore Plateau north of Dwarka headland.
(View looking northwards.)
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ug whyydaotpuag soak % JO UMord ayed oy. YSU oy. oF opAIT v pur yr puokaq ‘yoor ve uo peyprad astods
BSE ottad oF UP HoWAK 9yZ eAoqu Surtvodde (Wyjydanoupuag) sureuodopy Auuds pur ‘(s
SUVI-BIG
‘InoqueH, yAag ‘nly 1B api, Moy Ajawauyxea uy
POT MIPUDTE DION vuplar sf iy ojo |
MARINE ZOOLOGY OF OKHAMANDAL MARINE RESOURCES, PLATE VIII
Fig. 1.—Discosoma, a giant Anemone.
Photographed in a state of full expansion in a pool on the Hanuman dandi reef.
The mouth is in the act of discharging a mass of excreta. One-sixth of actual size.
a8 te
[Photos by Vividha Kala Mandir, Baroda,
Fig. 2.—Hanuman Dandi reef exposed at low tide.
Note the well-marked plane of marine denudation and the outcrop of calcareous strata
in the foreground.
NOTE ON
THE INDUSTRIAL DEVELOPMENT
OF OKHAMANDAL,
BY
DEWAN BAHADUR V. M. SAMARTH, B.A.,
Sar Subha of Baroda State.}
1. The administration of Okhamandal Taluka is beset with many exceptional
difficulties; the district is situated far distant from the central Government
at Baroda; it is not easily accessible at certain seasons; a portion of its popu-
lation is of a turbulent character and is responsible for the introduction of dual
control in matters administrative; finally, the seasons are uncertain and the soil
is not fertile. Financially, the Taluka is a heavy drain on the general revenues of
the State.
2. But there is another and more cheerful way of looking at this distant
possession of His Highness the Maharaja Gaekwar. It is a place sacred in the
eyes of all devout Hindoos and the thousands of pilgrims who visit it from all
parts of India are able to attest the power and glory and beneficence of the Hindoo
Dharma Raj. And there is yet another way of looking at it; the very difficulties
of the administration are most certainly its opportunities. Here is afforded to the
student of Indian politics an object lesson of British and Indian officials co-operating
more closely and on more equal terms than elsewhere, in the daily duties of governing
1 This note was written by Mr. Samarth several years prior to my deputation to Okhamandal to
enquire into the marine resources of that district. It typifies that spirit of progress which pervades
the administration of Baroda under the wise and energetic rule of His Highness the present Maharaja
Gaekwar. I am specially pleased to insert it in this report as it throws an interesting light upon the
present condition and prospects of the people of a district once notorious for lawlessness and piracy,
and which has been a source of trouble alike to the Governments of India and Baroda for many
generations.—J. H.
35 E
36 OKHAMANDAL MARINE ZOOLOGY REPORT
a backward population and leading it, much against its will, upon the path of
progress in civilisation.
8. The details of the history of the Taluka during the past century are
sufficiently well-known. From piracy to settled civilised Government is a change
any community may be thankful for. One is not certain that this is the feeling
of the Waghers on whom peace has been imposed by the strong hand; but that
it ought to be and will be their sentiment, to my mind, is beyond doubt. But for
the unreliable disposition of the Waghers towards the new order of things, the
administration of the Taluka even from distant Baroda would not be difficult.
Out of a population of about 21,000 souls, about 4,000 are Waghers, a little over
1,200. of whom are adult males. This apparently insignificant proportion of the
population is at the root of most of the evil and mainly, if not solely, to keep them
in order entails an annual expenditure of over a lac of rupees necessitated by the
maintenance of a battalion of disciplined sepoys and the establishment of a British
Assistant Resident. The last Wagher outbreak took place 40 years ago. Since
then these tribesmen are gradually settling down, nolens volens, to quiet ways
and are taking to agricultural life. At the present day they have all turned
cultivators but they have not yet acquired the skill and the virtues of thrift
and industry which are so essential to make successful agriculturists. The dignity
of labour has not yet become ingrained, and other forms of manual labour than
agricultural they affect to despise. They should not be blamed; rather do they
stand in need of sympathy and pity for their present failings. Considering
their past, one ought to be satisfied with their present achievements. They are
less troublesome now than they were and will be less and less so, as the rate
of their progress in civilisation becomes accelerated. What is needed now is
to make them acquainted with skilled modes of agriculture and to teach them
some handicrafts. That is to say, they must be given opportunities to improve
their status in the world materially and mentally.
4, The other classes of the population of the Taluka are also more or less
backward in intelligence and enterprise, but the Waghers are very far behind
even them. With the Waghers I include the cognate tribes of Wadhel Rajputs.
Of the other classes, the Bhattyas are the most forward; they are good traders.
Next to them are the Memons, who as cultivators, as oil pressers, or as petty
traders, though poor, are well able to take care of themselves, except in regard
to elementary education. The Lavans too are thriving. It is the Waghers who
need direction and encouragement more than the others.
5. Okha is not totally devoid of mineral resources ; gypsum, manganese, and
building stone are all available. But in what quantities these exist and whether
it is possible to establish industries in these products having a fair probability of
SAMARTH—INDUSTRIAL DEVELOPMENT OF OKHAMANDAL 37
commercial success remain yet to be investigated. There is also salt which nature
produces in abundance and which can be had for the gathering. But political
circumstances are such that this source of wealth is allowed to go to waste. The
attitude of the British Government in this respect is not in my opinion helpful,
but this by the way. Finally there is the possibilty of developing a pearl fishery,
a question, however, which must be taken in hand by an expert.
6. Okha should be connected with the Kattiawar system of Railways, and
the port of Beyt should be improved. The advantages of so doing would be very
great. In the first place the disadvantages which exist at present owing to distance
from Amreli and Baroda would vanish. Under prevailing conditions two battalions
of sepoys have to be maintained, one at Dhari and the other at Dwarka; one of
these could be safely dispensed with and the expenditure involved in its upkeep saved.
It would be very easy to move troops to or from Dwarka and Baroda or Rajkot
were the Railway extended to Dwarka. Even if there were no other income
assured from the construction of a railway, the consideration that a saving of
expenditure on either the Okha or the Dhari Battalion would be effected, should
in itself be a strong incentive to the undertaking. But as a matter of course,
considerable revenue would accrue from pilgrim traffic which would increase immensely
and from trade which the port of Beyt would attract when connected with the
general Indian railway system. An important reason, besides the excellence of
these ports as safe anchorages, why trade would favour Beyt and Dwarka is that
being treated on a level with British Indian ports for purposes of customs tariff,
a status not granted to the neighbouring ports of Kattiawar, exports from Okha
ports would be, and actually are at the present day, exempted from customs dues
at British Indian ports; as for imports, we are free to tax them or not at our
pleasure, if they come from British Indian ports. These are important advantages
and would help a railway to earn good income should we construct it.
7. Of minor sources of wealth, Okha produces ghee, wool, sesame, and castor.
It is possible to develop tobacco cultivation and even cotton and although no
afforestation appears practicable owing to the violent winds which blow over it
saturated with saline matter destructive of vegetable growth, my idea is that the
non-arable waste land which exists in abundance may be planted with googul
which grows naturally if protected from goats, sheep, and camels and is capable
of yielding some revenue from its gum and from its wood which is used as
fuel when dried.
8. The great sources of revenue, next after the land tax (Rs. 32,850) which
is only nominal in it incidence, are the pilgrim tax (Rs. 35,900) and the customs
duties (Rs. 26,125). The total revenue of the Taluka from all sources is Rs. 109,250
and the total expenditure is Rs, 203,700, a normal deficit of Rs. 94,450 annually.
E 2
38 OKHAMANDAL MARINE ZOOLOGY REPORT
But one need not lose heart owing to such a state of things. Here is an
opportunity to strive and rise superior to difficulties.
9. I have indicated ways and means above whereby the Taluka administration
may be made self-supporting, namely :—
I. The construction of a railway and the improvement of the port of Beyt, and
II. The improvement of the status of the ryots by raising them in character,
intelligence and capacity.
Let us lay the foundation of a policy calculated to bring about these ends,
and await the result patiently; with the co-operation of the British authorities I
am certain we should succeed.
10. With regard to the education of the people my ideas formulated in the
following paragraphs have been more or less formed or confirmed by what I have
had the opportunity of recently seeing attempted in Ireland and in England. The
problem before the Irish Government in regard to certain parts of that country
is in many respects not dissimilar to the problem which confronts us in Okha. In
England the work attempted at the Red Hill Reformatory, which came particularly
under my observation, impressed me as being of the utmost practical value for us
as administrators of backward populations some of which are actually classed
as criminal.
11. Compunsory Primary Epvucarion.—Through the head to the heart;
this appears to me to be the most natural and suitable method of educating the
young. No satisfactory results can be achieved without first making the children
go through a regular course of primary education and in the present stage of
society in Okha and especially so far as the Wagher population is concerned, primary
education must be made compulsory, but its introduction must be gradual. To
commence with, it must be free, no fees being charged. At every convenient
village, there should be a well-equipped school and all children, boys and girls
of all classes, whether Wagher or non-Wagher, within a radius of three miles, should
be under compulsion to attend school regularly between the ages of seven
and twelve except at busy times of agricultural work, such times to be fixed
with due regard to local conditions and the habits of the people. No more than ten
such schools would be required hesides those already existing at Dwarka, Varwala,
and Beyt. Schools were established at Aramda, Dhinki and Dhrasanwel which
owing to scanty attendance have heen closed and, although famine has left the
Taluka, have not been re-opened. These schools should be re-opened and the
buildings enlarged so as to afford accommodation for a much greater number of
children than they were intended for; the remaining seven schools should be opened at
convenient centres, with accommodation for the number of children belonging to
the neighbouring villages. Supposing Rs. 500 (five hundred) to be the cost of
the buildings and outhouses of each school, the ten schools would cost Rs. 5,000,
SAMARTH—INDUSTRIAL DEVELOPMENT OF OKHAMANDAL 39
out of which about Rs. 200 for each of the existing two schools at Goriali and Wasai,
making a total of Rs. 400, may be deducted, leaving only Rs. 4,600 to be provided
as initial cost of buildings. About Rs. 50 worth of furniture would be required
for each school, which for ten schools would be Rs. 500 more. Rs. 5,100 would,
therefore, be about the initial outlay involved on the primary schools supposing
there be no payments required for the salaries of schoolmasters. To effect
this latter object I propose to submit proposals for the amalgamation of the
Revenue Mehtas with the educational village school staff. In this way the
village Mehtas (Talatis) in Okha may be utilised as teachers. There will be in
that case no expense except on school buildings which will also serve as
choras. J think this scheme, if properly carried out, ought to answer satisfactorily
and with one person appointed to each school, the monthly expenditure on salaries
and contingent expenses need not exceed Rs. 20 per school or Rs. 200 for ten
schools, or Rs. 2,400 per annum. Books and slates the parents of the children
may be expected to pay for in consideration of Government providing the school
buildings and the teaching staff. According to the census of 1901, taking only
Wagher children, there were :—
Age. Boys. Girls. | Total.
{
|
5-12 years 640 831 1471
12-15, 255 185 440
There would be about an equal number of children belonging to other classes in the
villages. If we omit girls for the present owing to prejudice on the part of the
parents, the number of pupils (boys only) to be taught in schools will be very
manageable.
12. Of boys between the ages of 12-15 I would take only 10 per cent., which
for all classes need not exceed 75, and for Waghers alone only 25. I would take
only the Wagher boys, leaving the other classes to voluntary effort after 12. These
25 Wagher boys should be taken to Dwarka and a boarding establishment formed
for them at State expense.’ Here they should be taught higher vernacular standards
and practical instruction afforded in agriculture, weaving, carpentry and smith’s work.
A farm of about ten bighas and a workshop should suffice for all their education.
My idea is that the annual expense under all heads on this institution should not
exceed Rs. 2,500 exclusive of the initial expense of a suitable house and furniture.
A house may be hired or built.
18. These twenty-five boys should eventually be started in their respective
trades, for which purpose a small advance in money or material may be made to them
1 We may postpone this, however, for three or four years to await the results of the village
primary schools.
40 OKHAMANDAL MARINE ZOOLOGY REPORT
not exceeding, say, Rs. 50 each. But this item may be determined when the time
arrives, judging separately the needs of each individual case.
14. The teachers for agriculture and the technical crafts need not be highly
paid. Practical men from each trade may be selected as foremen on a small salary.
This is what is done in schools in England and Ireland.
15. The boarding Institution need not be continued as a free institution beyond
a period of ten years. It is expected that at the end of that period the people will
have learnt to appreciate the value of practical education and will be willing to share
the cost of it with the State, to the extent of half at least. Similarly after ten years
the cost of village primary schools will be shared with the people, half and half, for
another period of ten years.
16. It would also be expedient to encourage higher education among the
Waghers by offering one or two scholarships of suitable value to deserving boys.
17. So far my scheme for the education of the Wagher youths would appear
to be complete. It requires to be supplemented for a few years in the case of adult
men who cannot be sent to school. Ten Waghers not older than thirty years may
be selected for a special course of training every six months during a period of
three years. In this way there will be about sixty Waghers in all during the course
of three years who will be placed under training. For the present only one branch
of industry may be taught them, say, by preference, weaving cloth from cotton or
woollen yarn. There is demand for the rough cloth called Khadi such as is used
in the country, also for sail cloth; the making of Dhurries may also be taught.
Six months should be quite enough in which to teach the men these varieties of
weaving. After they have become proficient at their trade they may be dismissed and
then to enable them to start in business, implements of weaving may be advanced
to them as Tagavi, the value of which may be recouped to Government by small
instalments to commence from the beginning .of the second year. Should they find
difficulty in obtaining a ready market for their productions among local traders, for
two years Government might give them work by advancing materials to last for a
month at a time and receiving in return the finished articles to be paid for at a
reasonable price fixed according to the state of the market at the time. Such
articles Government would then sell direct or through middlemen as may be found
the more profitable or desirable. Government must be prepared to incur if need be
a small loss on this business regarding it merely as an educational measure adopted
for the purpose of familiarising the Waghers with handicrafts and home industry.
18. For the purpose of instruction and supervision I should utilise the services
of the jailor at Dwarka. He may be granted an allowance for doing this extra
work and an advance of Rs. 1,000; but the expenditure on this experiment should
not exceed Rs. 5,000,
SAMARTH—INDUSTRIAL DEVELOPMENT OF OKHAMANDAL:- 4]
19. An agricultural expert, a practical Kheddot, may be employed upon the
agricultural scheme; his salary and travelling allowance need not exceed Rs. 25
per month and he may be allowed about Rs. 200 per annum for expenditure in
connection with the purchase of seed, manure, etc. His business would be to teach
cultivators, whether Waghers or non-Waghers, better methods of cultivation, manuring,
selection of seeds, ete. His appointment would be for five years. On the expiration
of that period the question of his retention may be reconsidered in the light of the
experience gained from the results of his work in regard to improvement in general
agricultural knowledge and skill among the people.
20. I feel certain the above measures, if adopted, will result in a great
advance in the general well-being of the people and will entitle Government to their
gratitude to a much greater degree than even the humane and generous policy followed
in regard to famine distress has already evoked. The railway will be a great
civiliser; the improvement of Beyt port will bring business, and education will fit
people to appreciate and follow a life of industry. They will become more law-
abiding than they are; much of the expenditure on the military force maintained
at present it will then be practicable to curtail. The Wagher population which is
at present forced to stay at home will be fit to emigrate as skilled wage-earners
outside the limits of Okha to Karachi or Bombay or to distant Africa in the wake
of the Bhattyas and Memons.
21. In conclusion I wish to state that I think Okha requires a highly
centralised administration. Backward people fail to understand the real significance
of a division of Administrative powers. Our chief official’s position should be one of
equal value, so to say, with that of the Assistant Resident. I have proposed in a
separate vernacular memorandum the formation of such an administration.
I have also submitted memoranda for (1) the improvement of the pilgrim tax ;
(2) of the customs tariff; (3) of the fees for quarrying stones; and (4) I am in
correspondence with the Settlement Commissioner on the subject of the existing
mismanagement of the temple of Dwarka on the satisfactory conduct of which so
much of our fame and revenue depends and which to the minds of all devout
pilgrims is a grave scandal at present.
V. M. Samarra.
Subha, Amreli Division.
[Nore.—Most of the recommendations contained in the above note after con-
sideration by the higher authorities have been adopted, with varying results, since its
submission in the official year 1902-03 a.p.—V. M. 8.]
REPORT
UPON THE
ANATOMY OF PLACUNA PLACENTA,
NOTES UPON ITS DISTRIBUTION AND
ECONOMIC USES,
BY
JAMES HORNELL, F.LS.,
Superintendent of Pearl and Chank Fisheries, Madras.
[With Five Plates and Two Text Figures.]
THE anatomy of the window-pane oyster (Placuna placenta, L.) has never been
worked out, and references to it in the literature of the Lamellibranchs are scarce. The
literature of the genus Anomuia, to which Placuna is most nearly related, is likewise
scanty. The principal is by F. J. H. Lacaze Duthiers, who published in 1854 a
“Mémoire sur l’organisation de l’Anomie.” }
A short critique of this by Pelseneer appeared in 1891,? in which he amplified and
corrected certain points, while Sassi? has contributed an important paper dealing
principally with the renal system. Von Ihering* and Morse® have also treated of
Anomaa, and occasional references to this genus are to be found scattered through works
dealing with the morphology of molluscs, but Placuna, though well known by reason
of the minor economic uses which it subserves, has hitherto failed to attract that
attention from the morphological standpoint which it undoubtedly deserves; the
peculiar asymmetry exhibited by many of its organs possesses extreme interest when
considered in conjunction with habits and habitat, while the strange mingling of primi-
tive or archaic characters with others of extreme modification and specialisation has
much that will repay careful study.
1 Ann. des sci. nat., Zoologie, ser. 4, tome ii. 1854.
2 “Contribution 4 l’étude des Lamellibranches” (Archiv. de Biologie, tome xi. 1891).
3 “Zur Anatomie von Anomia ephippium” (Arb. Zool. Inst. Wien, xv. Heft 1, 1903).
4 “Ueber Anomia,” ete. (Zeitch. fiir Wiss. Zool., tome xxx., vol. supplem., 1878).
5 “On the Relations of Anomia” (Proc. Boston Soc. Nat. Hist., vol. xiv. 1871).
43
44 OKHAMANDAL MARINE ZOOLOGY REPORT
The general characters of the family Anomiide, which comprises Anomia and
Placuna as its two distinctive genera, may be summarised as follows :—
The organs exhibit a very high degree of asymmetry and the shell is distinctly
inequivalve. The valves show a pronounced tendency to assume an orbicular outline,
and are very much flattened or compressed laterally : the right valve is almost flat, the
left weakly convex.
In young specimens the shell is thin and more or less translucent ; the periostracum
is very delicate, and disappears soon after formation. Pigmentation of the adult shell
is rare, though it is common among young forms to show a beautiful satiny pink or
yellowish lustre.
The mantle edges are free and siphons are absent. A single adductor muscle (the
posterior) is present, large, and situated sub-centrally. The foot is fairly well developed,
either tongue-shaped or cylindrical. In Anomia the byssus is modified into a Jarge and
important calcified organ serving for fixation; in Placuna a byssus is absent, even in
the very young. -
The visceral mass is asymmetric, the right aspect of most of the organs being
developed at the expense of the left. The crystalline style is lodged almost entirely in
the right mantle, and practically the whole of the reproductive glands are likewise in
intimate association therewith.
The intestine is short, and lies posterior to the stomach. The crystalline style is
of enormous relative length. Special sense organs, other than tactile, are little
specialised. The heart lies dorsal to the rectum and projects freely into the pallial
cavity : no pericardium is present, and the coelomic cavity is reduced to insignificant
or vestigial dimensions. There is a single aorta—the anterior.
The genital glands open into the kidneys. The sexes are separate as in the true
pearl oysters (Margaritifera spp.).
The two ctenidia are smooth, with simple reflected tubular filaments, and are
organically fused together along the median line; each has a supplementary (or fifth)
external lamella which is free and unattached to the mantle. The filaments are parallel
and practically free, there being neither interlamellar nor interfilamentary organic
unions; cohesion is effected by means of interlocking cilia situated on the opposing
lateral faces of successive filaments: in Placuna certain of these ciliated areas are
developed into true ‘ciliated discs” ; in Anomia the opposing cilia interlock, but are
not specialised into “‘ discs.”
The genera of the family Anomiide, as already pointed out by Pelseneer, by the
ensemble of their organisation, are among the most archaic of existing Lamellibranchs
—notably in the simple structure of the branchiz, in the position of the heart dorsal
to the rectum, in the muscular structure of the auricles and in the absence of a
posterior aorta.
With these persistent archaic characters are associated several curious and highly-
HORNELL—ANATOMY UF PLACUNA 45
developed specialisations, the chief being,-in Anomia, the calcified byssus, and in
Placuna the single genital aperture, and the development of the foot into a very long
and trumpet-shaped organ.
In both genera the unequal development of the two nephridia and the obliteration
of the pericardium are most noteworthy ; in Anomia Pelseneer held (loc. cit.) that the
pericardial coelomic cavity is reduced to an insignificant connecting channel between
the kidneys, but Sassi contends (loc. cit.) that the coelomic cavity is represented by
certain groups of saccate glands opening into each nephridium; in Placuna, as I
believe and suggest, it is to be correlated with a glandular body on each side, which
opens into the anterior horn of the kidney of its side—a view which strengthens
Sassi’s contention regarding the organs he describes in Anomia.
Before entering upon a detailed description of the organisation of Placuna
placenta, it may be useful to give here a brief résumé of the distribution of the species
treated of, with notes upon the economic uses to which it is put.
DISTRIBUTION AND HABITAT.
Placuna placenta, Linn, has a range extending from the Arabian Sea on the
west through the Indian Ocean and Malayan Seas to the coast of China on the east.
The special habitat favoured by this mollusc is the muddy bottom of coastal bays ;
in many cases these bays are more or less completely landlocked, with a characteristic
association of mangrove swamps along the shores; frequently the water of such bays
is slightly brackish by reason of the rivers and streams that debouch thereinto.
Placuna placenta appears, indeed, to be able to withstand a considerable admixture of
fresh water, as we find it in such muddy estuaries as Karachi Harbour and other bays
and creeks on the outer edge of the delta of the Indus; even in tidal rivers and
backwaters cut off from the sea by surf-beat sandbars Placuna thrives, as, for example,
in the Sambore River and the adjacent backwaters near Trincomalee in Ceylon. In
Tampalakam Bay, also in Ceylon, I have found the specific gravity of the water over
the Placuna beds to range during the dry season as low as 1:019 to 1°015 at
temperatures 87° to 90° F., the open sea being 1°023; in the rainy season it must be
notably lower.
On the other hand, the past fishery experiences of the Tampalakam beds have
shown that an unusually large influx of fresh water during an exceptionally wet season
entails the destruction of the oysters. The same adverse influence of an excessive
admixture of fresh water has been noted at the window-pane oyster fishery near
Tetabuan, on the east coast of British North Borneo, where the flow of the adjacent
rivers in flood not infrequently causes widespread mortality.
With all this adaptation to life in distinctly brackish shallow water areas, I have
found that Placuna placenta is capable of attaining large individual size, and of living
46 OKHAMANDAL MARINE ZOOLOGY REPORT
in robust health in the open sea and at a depth of several fathoms. Thus, I have seen
quantities thrown up on the open beach at Nilaveli, some seven miles north of
Trincomalee, and, again, during a cruise of the steam trawler Violet, during the past
summer (1907) along the Coromandel coast, numerous specimens were trawled in the
open sea from a muddy bottom in seven-fathoms, at a distance from seven to nine
miles eastward of Negapatam; I have also several dead valves trawled from the
Periya Par, one of the Mannar pearl-oyster banks, situated twelve miles off the west
coast of Ceylon. More recently I have found living individuals cast up during stormy
weather along the coast adjacent to Madras.
The shells of those individuals that live in shallow bays and creeks are perfectly
transparent for the greater part of the first year of life; the general anatomy of the
animal can be seen, even to the beating of the heart. At this stage the valves are
clear as the finest mica flakes, which they resemble closely, even to the readiness with
which they may be split into further lamine. As they become older the valves
assume a more massive appearance, and generally turn white and translucent in place
of being clear and transparent.
The very young, up to the time they reach a diameter of two inches, not
infrequently exhibit ray bands of pale transparent pink diverging from the hinge,
and broadening as they approach the free edge of the shell. A few are almost entirely
suffused with this pale pink tinge, but the great majority exhibit no colour even in the
youngest stages, and all shallow-water shells become colourless and sub-translucent after
one year and a half.
A marked distinction between the shallow-water (brackish water) forms and those
I have seen from the open sea is that in the latter a well-marked reddish-brown radial
banding of the shell appears to be normal. It was characteristic of the great majority
of the trawled individuals, and was persistent in the largest specimens examined (twelve
centimetres diameter), whereas, as already stated, red colouring is transient, and
comparatively uncommon in those found in muddy bays. The tinge among the latter
is also much fainter, lacking the intensity and depth that is a noteworthy characteristic
of those from several fathoms in the open sea.
The bottom favoured hy Placuna placenta is a fairly stiff or pasty greyish-black
mud. On this the shells generally lie prone upon their convex left valves, the hinge
region sometimes slightly sunk in the mud, which may lightly cover the dorsal
third of the shell. Native divers also aver that occasionally they are sunk more deeply,
and that they may even be found, though this is rare, planted vertically after the
manner of Pinna ; if so, this is an abnormal position, and one which, I believe, must
quickly entail death.
Few conspicuous animals are associated with Placuna placenta. Both flora and
fauna are scarce ; few organisms have adapted themselves to life in such environment.
In Tampalakam Bay the only other animal of importance and abundance is the peculiar
HORNELL—ANATOMY OF PLACUNA 47
suberitid sponge known as Kadalpalam (sea-fruit) to the Tamil divers. In the Gulf
of Kutch a similar or closely related suberitid is associated with Placuna, and in the
same locality we also find Lingulw and a large yellow Dendronephthya living on the
same ground. Algz are scarce, and those seen are all green and mostly fleshy
genera such as Codiwm. The valves of Placuna seldom bear any crusting or parasitic
growths such as are so familiar on the shells of the true pearl oyster (Margaritifera
vulgaris). When such are present they consist chiefly of sheets of encrusting Bryozoa.
I have never seen the valves attacked by the burrowing sponge Clione, but the
tubular burrows of the polychet Polydora are sometimes not uncommon. The sandy
tubes of another polychet, Hunice indica, are also at times fairly abundant attached to
the valves.
Placuna does not appear to have many enemies; fishes are the principal, and
their damage is largely confined to biting pieces out of the margin. Shells so
mutilated are not infrequent; photographs of two shells so damaged are shown in
Plate I, fig. 2. Larval parasitic worms, both cestodes and trematodes (figs. 20 and 21),
are frequently seen encysted on the mantle edge, and as fragments of this are ingested
every time a fish bites a piece out of the margin of a Placuna shell, it is clear how the
parasitic infection is passed on to a fish host in which the parasites will become sexually
mature.
A remarkable feature in this connection is the early age at which the infection of
Placuna may take place. I have sections through individuals of which the shell and
the visceral mass are but 1°5 cm. and 4 mm. in diameter respectively, showing well
developed larval cestodes (? Tetrarhynchus) encysted in the liver.
DETAILS OF DISTRIBUTION.
The following list comprises all the localities of which I have knowledge. It will
be seen that it gives a chain of habitat practically unbroken from the mouths of the
Indus to the south coast of China :—
India.—Karachi Harbour and numerous inlets and creeks along the Sind coast ;
Gulf of Kutch (Balapur Harbour in Beyt Island! and Rann Bay !); Bombay
Harbour and vicinity ; Malabar Coast; muddy creeks south of Tuticorin! Buckingham
Canal and Pulicat Lake (Madras Presidency)! open sea off Negapatam in seven
fathoms! thrown up on sea beach, Ennore, near Madras! Mergui Archipelago.
Ceylon.—Tampalakam Lake! Sambore River and adjacent backwaters (Willey) ;
open sea off Nilaveli! (these three localities near Trincomalee) ; off Delft Island, Palk
Bay, six to seven fathoms! dead valves in nine fathoms, Periya Par, Mannar Pearl
Banks !
48 OKHAMANDAL MARINE ZOOLOGY REPORT
Malay Archipelago.—Vavious places in the Dutch Indies ; North Borneo, notably
at Labuk Bay ; the Philippines; also in Cochin China and Southern China.
Diving for Window-pane Oysters in Rann Bay, Okhamandal.
ECONOMIC USES.
The name window-pane oyster, which travellers in Southern China have given to
Placuna placenta, indicates the use to which this shell has been, and is even yet, put
in some Eastern countries.
During the days of Portuguese rule in India, when window-glass was a searce and
costly commodity, these shells were extensively used in the Portuguese settlements as a
substitute. Fryer recorded this in 1675 ; the custom lingers in Goa to this day. Max
Weber, writing in 1906, states that this window-glazing is still to be seen at Menado
in the Dutch Indies and also in the Philippines. In Canton and other districts of
Southern China, its use for the same purpose also continues ; lastly, quite recently
(1907) I saw a verandah at the Chinese Club at Cholon (Cochin China) roofed with these
shells, while in the adjacent stream which intersects this town Annamite women were
busy soaking and cleaning such large quantities of the valves as indicated considerable
demand.
The shells chosen for the purpose of glazing are half-erown individuals: I should
judge them to be eighteen months old. After soaking some time to effect the decay of
the Hesh, the shells are cleaned by being tossed and shaken together in baskets till all
dirt and roughness are removed and a translucent mica-lke appearance 18 obtained.
HORNELL—ANATOMY OF PLACUNA 49
The former fishery near Bombay was to furnish shells for the purpose of
window-glazing ; so also is the collection that goes on in the Dutch Indies, Borneo,
and the Philippines.
It would be interesting to discover the origin of this utilisation of Placuna shells ;
it is scarcely likely to have originated independently at such widely-separated localities
as China and Western India. I am inclined to credit its origin to the Chinese, and its
dissemination to the Portuguese, who in the height of their power linked up East and
West as Britain does to-day. At their great trading centre of Macao, close to Canton,
they would early become familiar with the Chinese use of Placuna shells, and their
officials would thence carry this knowledge to the scores of stations dotted along the
coast-line of the Indies.
Tn certain localities Placuna placenta produces quantities of minute pearls, but
as these suffer from the four vital defects of small size, poor lustre, irregular shape and
lack of the great hardness characteristic of gem pearls, their value is low, and the
uses to which they are put are such as will lose importance when fanciful medical
nostrums and old superstitions give way before the advance of iconoclastic Western
ideas.
.To meet this curious demand there are at least four localities where beds of
Placuna placenta are fished more or less intermittently and irregularly for the sake of
these seed pearls. ‘hey are those of Sind (Western India), Tampalakam Bay in
Ceylon, Labuk Bay in North Borneo, and the Dutch Indies.
The fishery in Sind is of comparatively recent origin. It was discovered by the
Mirs about 1836. Since the British Government took possession of Sind, the fishing of
the banks has been leased by Government periodically for very variable amounts,
ranging from the comparatively high figure of Rs. 6,205 in 1849 to as low as
Rs. 617 per annum for a period of three years in 1904, a gradual diminution of
revenue due without doubt to over-fishing and the financial impossibility of maintaining
a supervising establishment adequate to enforce a proper regard for cultural safeguards.
‘The industry in Ceylon has run a parallel course ; it has a similar tale of gradually
diminishing prosperity, due to over-fishing and poaching. As on the Sind coast, the
Ceylon Placuna fishery is the property of Government, and the leasing-out system is
also the one adopted. Under the circumstances which prevail at Tampalakam, and the
comparative pettiness of the industry, this would seem to be the only practical method.
What is wanted is efficient supervision, but here, as in Sind, it is difficult to reconcile
theoretical requirements with financial soundness.
A detailed account of the Ceylon industry, and of the physical and biological
conditions of the Placuna placenta beds, will be found in Part II, pp. 41 to 54, of the
Ceylon Marine Biological Reports (1905).’
Since then an ordinance has been enacted formally vesting the monopoly of the
1 Also as Ceylon Government Sessional Paper, No. xlvi., 1905.
50 OKHAMANDAL MARINE ZOOLOGY REPORT
fishery for window-pane oysters in the Ceylon Government, and giving powers to the
authorities to make regulations for a close season, a minimum size limit, and other
protective and cultural measures which may be considered desirable from time to time.
The lease of the beds at Tampalakam was next advertised, and was taken up in
December, 1906, by a native syndicate at an agegregete rental of Rs. 17,700 for a term
of five years from January, 1907. Among the stipulations were (a) a minimum size of
five and a half inches in shortest: diameter of the shells, and (b) a close season
extending from May 15th to the end of December in each year. The results of the
first year’s fishery proved a dismal failure, largely owing to previous extensive poaching.
The total of oysters fished is stated by the lessees at 627,672, the number being known
with exactitude, as a payment of 25 cents (=fourpence) per thousand is made for
opening them. From this quantity the lessees declare they obtained but forty-six
rupees weight (say 46 tolas) of pearls, worth about Rs. 690, or one rupee ten cents (say
one shilling and sixpence) per 1,000 oysters !
The seed-pearl fishery in North Bornean waters is less well-known than either of
the preceding. It also is owned by the Government, but in spite of being situated in
a wild region, where civilisation has but recently appeared in the persons of a handful
of European officials, it appears to be under more efficient regulation, and to promise
a more continued prosperity than in the case of Ceylon and Sind.
The principal banks of window-pane oysters occur there in Labuk Bay, and are
largely fished from Tetabuan, a village inhabited by Bajaus, a Malay tribe that: till
recent years lived largely on the spoils of piracy eked out with desultory fishing.
To-day the Pax Britannica compels a steadier life, and accordingly the Bajau has
turned fisherman in earnest. He is skilful at his calling, and being a fairly good diver
as well, he is able to take toll from the beds of Placuna placenta that exist literally at
his door—his dwelling is on piles on the margin of mangrove swamps.
The Tetabuan fishery is carefully regulated with the co-operation of the village
chief. No shell is allowed to be fished under four inches in diameter, and no one is
allowed to search for shells without a licence.
From time to time, as the oysters mature, certain of the banks are opened to
fishing. At such times the boundaries of the bed are marked out by flags, and the
village chief superintends operations, seeing that neither immature oysters be fished,
nor unlicensed divers be present. As in Ceylon, the water over the Tetabuan beds is
quite shallow—eight to nine feet. Diving requires no apparatus save a rattan basket
wherein to place the shells.
On return from the banks the women and children take charge of the oysters.
First of all the shells are opened and the contents thrown into a large iron pan of
water. When filled the pan is put on the fire and slowly heated, but not to boiling
' Dr. A, Willey, “Report on the Window-pane Oysters (Placuna placenta) in the backwaters of
the Eastern Province,” Spolia Zeylanica, vol. v., pt. xviii, Colombo, 1907.
HORNELL—ANATOMY OF PLACUNA 51
point. The contents are then placed in a tub and allowed to remain for three days
till thoroughly putrified.
When thus prepared the rotten mass is taken up, a small quantity at a time, and
rubbed well between the palms of the hands, and allowed to drop into a dish of clean
water, where the small pearls fall to the bottom. From time to time the dirty water
is decanted an1 replaced by clean. So the process proceeds till all the flesh has been
treated, when, after final rinsing, the seed pearls, called selisip by the Bajaus, are
strained off, cleaned and dried, and made ready for the market.
They are sold by weight; the prices paid generally give the Bajau divers a fair
return for their labour.
The Borneo seed pearls are bought up by Chinese dealers and exported to China,
where the bulk is used in the preparation of various quaint medicines. The Chinese
specially esteem pearl medicaments in diseases of the eye, and I have been told by a
Chinese doctor that ground-up pearls are considered a specific for syphilis.
Some of the produce of the Ceylon Placuna fishery also finds its way to China,
but the bulk from Ceylon and Sind is consumed in India, either as a component in
native medicines, or calcined to form a luxurious form of chunam to smear on betel
leaf used in chewing, or as a cosmetic by native ladies. The value of the Sind
produce is given as Rs. 15 per tola, the same rate as that current in Ceylon, where
one rupee’s weight (equivalent to one tola) of these pearls passes current at a similar
price. Any exceptionally fine and large pearls are, however, taken out from the bulk
and sold separately.
Before entering upon the detailed description of the anatomy and histology of
this mollusc, it affords me great pleasure to acknowledge my indebtedness to two
helpers, Mr. T. Southwell, A.R.C.S., and Mr. George Henry, whose skilled assistance
was always most willingly given. Mr. Southwell was kind enough to prepare and cut a
large series of serial sections of young individuals, and to help very considerably in
working up this material, while the extent of Mr. Henry’s help may be gauged by
reference to the very beautiful drawings which add so much to the value of this paper.
To Mr. Edwin Wilson, Cambridge, I also tender my sincere thanks for the great
care and skill he has bestowed in reproducing the drawings upon stone; the result is
everything I desired.
THE SHELL.
The shell of Placuna placenta in the fully-grown condition is free, greatly com-
pressed, and distinctly, though slightly, equivalve. ‘The outline is sub-orbicular,
the longitudinal axis (length) to the vertical axis (height) being an average of
1554mm. to 1424. mm. fora number of the oldest generation of these shells collected
in Lake Tampalakam in 1905. Strangely enough, 155 mm. by 142 mm. were the
precise measurements of the largest living specimen I have collected in the. Gulf of
F
52 OKHAMANDAL MARINE ZOOLOGY REPORT
Kutch. Series of younger generations give almost practically the same ratio—in one
case 114,8, mm. to 102 mm., and in another 1254 mm. to 115mm. We may, therefore,
take the ratio of length to lateral height or depth as 11 to 10, both for adults and
immature individuals.
This slight inferiority in the height is due to peripheral growth being largely
arrested along the central portion of the dorsal line, where a linear hinge forms the
junction between the two valves. In consequence, adult shells show a straight edge
along the most dorsal region, measuring approximately one-fifth to one-fourth of the
extreme length of the valves. This particular feature, however, may exhibit consider-
able variation; the hinge region in some shells may even assume an obtuse-angled
outline.
The right valve is almost flat, the left slightly, but appreciably, convex externally.
In many adult individuals the mid-posterior region of both valves shows a single wide
shallow lateral depression or contortion, extending some distance inwards from
the margin, and with its convex aspect to the left side of the shell. There is
occasionally a similar but much less distinct bending in the mid-anterior region
of the shell, vis-a-vis to the posterior one. ‘These two lateral contortions exhibit a
considerable degree of variation both in the extent or area in which they involve the
valves and in their relative proportions. Thus specimens are seen where the anterior
folding is larger than the posterior, and in others one or other may be practically
non-existent.
Such contortion as is indicated here is developed to a maximum in Placuna sella,
a large and massive species of distinct saddle shape, separated from Placuna placenta
principally for this reason. In this connection it is interesting to see occasionally
among old individuals of the latter species, instances where contortion is sufficiently
well marked to exhibit suggestive approximation to weakly-contorted specimens of
Placuna sella.
I have said above that the outline of the shell is sub-orbicular. So it is typically,
but rather because of the inevitable damage to delicate shell growth that takes place
from time to time as the shell increases in age, and which tends to remove more or
less completely any thin outgrowths that depart from the circular outline.
In very young individuals of 2 ems. and thereabouts in diameter, the sub-orbicular
form without any marginal outgrowths is normal, and such show the straight dorsal
hinge line clearly, and a slight unbonar beak. In slightly older specimens, where
the shell has attained a diameter of about 5 cms., it is found that the portions of the
dorsal margin of the shell at each end of the hinge line begin to grow more rapidly
than the rest of the margin, and thus form one or several rounded ear or wing-like
lobes at either end of the hinge (Plate I[., fig. 1). With the growth of the shell these
ears may become very prominent, and attain a length of from one to two centimetres
(Plate II., fig. 2, a.e.). Frequently in young shells two, or even three, of these “lobes”
HORNELL—ANATOMY OF PLACUNA 53
may appear at the anterior end of the dorsal margin ; at the posterior end a single and
larger lobe is usually developed. In rare and extreme cases one of these “ears” or
lobes ‘at each end of the hinge line, growing out at right angles to this line, becomes so
pronounced that they include the hinge region in a deep bay. In adult shells these
ear-like lobes usually become broken off, but remnants of them may generally be
traced.
The anterior, ventral, and posterior margins of the valves in undamaged adults are
typically entire; such a margin is frequently seen in immature individuals, but a large
proportion of the larger shells show irregularities due in the first instance to injuries
inflicted by fishes. Plate I., fig. 2 (A and B), shows two extreme instances. In the
former (A), several injuries of old standing are recorded in the irregular or “‘ bayed”
appearance of some of the old concentric growth-lines, while the ventral edge shows a
large one of recent infliction, as indicated by the clearness of the edges of the semi-
circular gap resulting from a fish’s bite. As in the true pearl oyster (Margaritifera
vulgaris), reparation of such injuries is extremely rapid, and so long as the bite affects
no organs or tissues except the mantle edge, Placuna placenta possesses great
recuperative powers. Such injuries have economic interest, as they constitute an
effective and necessary factor in the life-cycle of the cestode and trematode parasites
whose larvee form the nuclei of many Placuna seed pearls.
The outer surface of the shell is marked by distinct concentric lines of growth,
consisting of slightly projecting imbricate lamelle, the margins of which are rendered
minutely uneven or roughly dentate by the presence of numbers of short, closely set
and very delicate processes, spatulate or finger-like in form, and rather ragged in their
irregularity and wear (Plate I., fig. 2).
These concentric rows of minute processes impart to the shell a certain roughness
to the touch ; they occlude many particles of mud, and this is apt to give the shell a
dirty brownish colouring, and the false appearance of having a rough superficial
periostracal investment.
The two valves of the shell are united dorsally by a short hinge ligament
coincident with the greater part of the straight dorsal edge. On the dorsal edge the
ligament is straight, while on the ventral two very long linear projections, and a
number of short, narrow dentate ones are seen, corresponding in position and size
with a similar number of projecting teeth arming the hinge line of the opposite right
valve (Plate IL, figs. 2 and 3). So relatively strong is the ligament that a small
portion of the dorsal margin of the right valve is usually broken off, and remains
attached to the ligament when the valves are forcibly separated.
In very young specimens the hinge ligament is dark golden brown ; with age the
colour deepens, till in the fully mature it becomes a brownish black with a bronze green
lustre.
On the right valve two very prominent cardinal teeth arise close together at the
F 2
54 OKHAMANDAL MARINE ZOOLOGY REPORT
central point in the hinge line. They are long, narrow, and greatly compressed.
laterally ; they run ventrally, diverging as they go. The posterior is considerably
the longer of the two, measuring over 2 cms. in fully-grown shells, whereas the anterior
is but 1:5 cms. long. These teeth have their free edges slightly rolled or curved
outwards upon themselves in such a way as to give the ligament a very secure grip
(Plate IT., fig. 1).
A number of minute teeth occur on each side of the cardinal projections and
parallel with them, so that those in front of the anterior cardinal tooth run anteriorly
and ‘ventrally, and those behind the posterior cardinal, towards the posterior and
ventral aspects. | Frequently one, or, less frequently, two minute teeth occur between
the cardinals.
All these small hinge teeth alternate with papilliform terminations along the
dorsal aspect of the mantle ; in young specimens, up to 2 cms. long, they are absent.
In the three spaces or pockets formed by the cardinal teeth and their ligaments,
lie three corresponding dorsal portions of the mantle.
The internal surface of the valves is smooth, with a high polish. The impression
of the single adductor muscle is situated sub-centrally, a trifle dorsal to the centre,
and is very noticeable. The minute insertion scar of the single pedal levator muscle
may usually be seen upon the left valve, a little posterior to the ventral extremity of
the anterior cardinal hinge ligament.
No well marked pallial line, such as we have in Cardiwm and Mactra, nor a
regular series of scars caused by the insertion of the pallial muscle bundles, as seen in
the true pearl oyster (Margaritifera vulgaris), can be distinguished. The only vestiges
of such are two or three narrow and elongated faint scar-impressions, a little anterior to
the antero-ventral corner of the adductor scar, and two others of smaller size at a
corresponding level behind it. In adult shells the map of the pallial muscles is
conspicuous as a fan-like radiation of shallow grooves; all the main bundles have
their corresponding impressions on the inner surface of each valve.
The shell in young and immature individuals is very thin, transparent, and usually
colourless, whence comes its popular name of window-pane oyster. When fully grown
the shell attains a thickness of about one millimetre, and losing its transparence
becomes sub-opaque, white, and somewhat friable, suggestive of dull white mica which
has lost its transparency through weathering.
The substance of the shell is composed of the same three layers as are characteristic
of most Lamellibranch shells, but here the organic basis is unusually well developed,
while the periostracum, or superficial horny layer (seen well in Unio and Arca), is
exceedingly thin and scarcely discernible even in young specimens, where it can
scarcely yet have been worn off by attrition or decomposition. In old specimens the
middle or prismatic layer becomes actually superficial, although the mud which lodges
in the roughness of the outer surface of the middle layer gives, as already mentioned,
HORNELL—ANATOMY OF PLACUNA 5d
a false appearance of a well-developed periostracum. Thorough washing, however,
reveals the mature shell to have no superficial horny layer, and to consist of twu
layers only, the outer sub-translucent and with a micaceous cleavage, the inner
transparent in younger specimens and sub-translucent with a marked pearly white
lustre in older ones.
That a delicate periostracum is actually secreted is shown distinctly in sections
through the mantle edge, where, as in Plate V., fig. 32, a delicate horny secretion
(pertost.) is seen in process of formation by cells situated at the base of the periostracal
groove exterior to the true pallial margin (mg. yp.).
GENERAL ORGANISATION.
In proceeding to a dissection of Placuna it is preferable to begin by removal of
the left valve, as the visceral mass and the majority of the organs are fused with or
sunk in the right mantle, whereas the left has retained very largely its primitive
character of a thin membranous fold serving as a loose envelope or cloak to the
remainder of the body.
When the left valve is removed, this left mantle is seen to have lined the inner
surface of the valve except at a sub-central spot where one end of the large adductor
muscle (add.) pierces the mantle to find insertion on the inner surface of the shell, and
at the few small scars made by the insertion of the pallial muscles.
The mantle edge is seen to be free at all points save dorsally along the hinge line,
where the two mantle folds meet and fuse. This dorsal union is complicated by the
intrusion of two enormous cardinal teeth (c.t.) with their ligaments, which entails this
dorsal region being split up into three portions—the central, bounded on either side by
a cardinal tooth, being conical in outline, while the two lateral are broadly spathulate,
and wider on the dorsal or free edge than at the base where they merge into the rest of
the mantle (Plate III, fig. 19).
The dorsal edge of these lateral lobes in its turn is further subdivided into minute
spathulate processes, sometimes slightly bifid at their extremities, which alternate with
the minute hinge teeth found on either side of the cardinals.
A small portion of the gonad penetrates these same lobes.
Removal of the unattached portions of the left mantle exposes the visceral mass,
foot, labial palps and gills (Plate II., fig. 4). The first three lie on the side dorsal to
the adductor, while the gills beginning a little way above the anterior aspect of this
muscle pass first forwards and downwards, and then posteriorly along its margin in such
a way as to bound it on two sides. The visceral mass occupies the space between the
hinge and the adductor muscle. Broad and tumid ventrally, it narrows somewhat
dorsally, giving off on that aspect two thin lobes to the anterior and posterior pallial
hinge flaps.
56 OKHAMANDAL MARINE ZOOLOGY REPORT
Projecting forwards from each side of the anterior aspect of the visceral mass is a
pair of lamellar palps (Pa.) as in other Lamellibranchs. In Placuna they are greatly
elongated dorso-ventrally and narrow relatively to their length. The opposing faces of
the members of each pair are deeply grooved transversely, and clothed with ciliated
epithelium. In common with the majority of organs in this species, the palps are
asymmetric, due to the mouth being placed to the right side of the median line. As a
consequence the upper and lower lips, which normally are prominent transverse folds
connecting the dorsal and ventral (outer and inner) palps of either side respectively,
are here twisted to the right, and come to assume rather a vertical than a transverse
position. The ventral margin of each inner palp bends inwards below the insertion of
the foot, and unites in the median line with its fellow from the opposite side.
The anterior tip of each ctenidium or branchia is led into and attached to the base
of the gutter formed by approximation posteriorly of the bases of the two palps of its
respective side. Beginning from this attachment each ctenidium is suspended through-
out its length from a wide mesentery, attached along its inner margin for a short
extent anteriorly to the kidney, and for the remainder and greater extent to the
mantle close to its junction with the adductor muscle in the case of the left mesentery,
and along the course of the stylar (ventral) visceral lobe in the case of the right
ctenidium.
Cutting away the gills and their suspensory membrane or mesentery close to the
adductor muscle, together with the left pair of palps, we are enabled to see clearly how
greatly interpenetrated is the substance of the right mantle by various lobes of the
visceral organs. Beside the two hinge-lobes already mentioned, the principal of these
are three in number, which may be termed respectively the posterior genital, the rectal,
and the stylar lobe (Plate IIL, fig. 13).
The first of these is an elongated, somewhat wedge-shaped tumid mass (Go.p.),
having its long axis directed obliquely posteriorly and ventrally ; a deep groove marks
it off from the posterior margin of the main visceral mass, connection being made by
a narrow bridge of tissue dorsal to the apex of the ventricle.
The rectal lobe lies ventral to the last named; it runs obliquely backwards from
the mid-ventral region of the main visceral mass at an angle of about fifty degrees from
the vertical, and terminates a little above and beyond the posterior extremity of the
gills. For part of its course it is attached ventrally to the surface of the adductor
muscle, while near its distal extremity it is approximated to the ventral end of the
posterior genital lobe, to which it is connected by a very narrow and inconspicuous
bridge of tissue. The rectum lies for most of its course within this rectal visceral lobe ;
at its posterior extremity the anus opens in the centre of a wide and shallow funnel
(An.f,, fig. 5).
The third visceral lobe is peculiarly interesting, as although it has no great bulk
its length is relatively extreme. Its position may be defined as parallel and coincident
{Photo by Viridha Kula Mandir, Baroda.
Anatomy of window-pane oyster as seen after the removal of the left valve and mantle,
showing the fine strands of the pallial muscles and the deeply pigmented ventral
pallial sinus within the right mantle, the gills, adductor muscle, foot, cardinal
hinge teeth, ete. Part of the pallial sense organ shows just under the posterior
tip of the gills. The great extent of the branchial mesentery is conspicuous,
and the outer accessory fold of the refleeted branchial lamella is discernible.
Two small pearls are seen in situ close together in the ventral region of the
mantle. x ?
[To face p. 56.
HORNELL—ANATOMY OF PLACUNA 57
with the direction and extent of the gills. It arises from the anterior ventral angle
of the visceral mass close to the lower margin of the palps, and extends thence in a
semi-circular and gradually narrowing band to a point midway between the anus and
the hinder limit of the adductor muscle. Embedded in it, and showing through it for
a considerable part of the distal portion, is the enormously long crystalline style.
The ventricle of the heart lies free within the angle made by the upper margin
of the rectal visceral lobe with the posterior edge of the visceral mass. As the
posterior genital lobe lies athwart the base of the angle so formed, an imperfect
chamber—the cardiac chamber—is formed, open, be it remembered, on the left lateral
face. No trace of pericardium is to be seen.
The foot (F.) is attached to the anterior surface of the visceral mass between the
two pairs of labial palps at about the level of the lower half of their length. The
attachment of the anterior extremities of the gills is distinctly ventral to the base of
the foot; in the pearl oyster (M. vulgaris) the apices of the gills bound the foot
laterally.
In Placuna the foot reaches a high degree of specialisation; it is extremely
mobile, and capable of great extension and equally great contraction. The form
assumed is that of a cylinder much flattened laterally. The apex is modified to form
a well-developed deep cup-shaped sucker with strongly developed muscles in the rim ;
in contraction the edges of the sucker are approximated, obliterating the cavity more or
less completely.
Within the walls of the sucker muscle fibres radiate from the centre of the pedal
axis. It would seem from this structure that the mechanism is similar to that of
a boy’s leather sucker—when the rim be everted and the surface of the cup applied
to a flattened surface, a vacuum will be created by the contraction of the radial
muscles. Were Placuna placenta to live on stony or rocky ground, this arrangement
would suggest that the animal employs this organ in locomotion to drag itself from
object to object. On the mud flats where it lives, this function cannot be employed.
From this consideration, and from observations made on the animal in an aquarium
tank, it seems to me that the principal use—if indeed it be not the sole one—the foot
here subserves is that of a cleansing organ.
In dissection the sucker cavity is usually found to be gorged with mud; where
Placuna lives the water is normally turbid with mud and flocculent vegetable debris in
suspension. The animal must have an organ to collect and clear away the foreign
matter which is continually settling and accumulating upon the surface of the mantle
and gills, and lodging in corners and cavities; an extremely extensible and flexible
cylindrical organ, bearing at its extremity a muscular sucker-cup armed with a highly
sensitive and mobile rim, is ideal for such purpose, and this appears to be the purpose to
which the foot is put by the window-pane oyster.
In a normal state of contraction, when this organ is at rest, it measures not more
58 OKHAMANDAL MARINE ZOOLOGY REPORT
than 1°75 ems. in diameter. What the maximum may be is difficult to say in respect
to fully adult animals, but 1 have note of an instance where on opening a living
specimen suddenly, and with a minimum of shock, the foot was seen to be bent
downwards, and to lie along the ventral side of the adductor muscle with the sucker
approximated to the anus. In this state of extreme extension it was somewhat reduced
in diameter; the length was slightly over six centimetres.
The substance of the foot is composed of networks of muscle fibres running in
various directions, the principal being longitudinal and radial. Others again are dis-
posed concentrically, and by these various series the foot can be deflected as required.
A weak levator muscle (fig. 4, Lev’.), difficult to discern without the aid of serial
sections, originates in the upper portion of the pedal base, and assists in retracting the
foot upwards, its insertion being in the left valve posterior to the ventral end of the
anterior cardinal tooth, while a similarly weak muscle bundle passes from the ventral
pedal base to the upper surface of the adductor, and is therefore the homologue of the
powerful retractors seen in Margaritifera. In Placuna a single bundle alone is
traceable, its insertion being in the left valve at the anterior dorsal corner of the
adductor muscle (fig. 31, Ret.), as is also the case with the two retractors present
in -Anomia.
Sections of partially extended feet show the muscular framework to be so
extensively penetrated by blood cavities as to be highly cavernous. Injection of these
spaces with blood produces extreme inflation or turgescence, which, as seen, enables the
organ to attain an elongation at least four times that of the contracted condition, and
in conjunction with the complex of muscles composing it and acting upon it, provides
for all the varied movements of which the foot is capable.
The blood supply is derived frem a stout artery given off from the anterior region
of the hepatie viscera] artery. Blood passing from the foot enters the left visceral
sinus and passes to the kidneys and thence to the gills.
The nerve supply to the foot comes from the pedal ganglion, which is situated
elose to and practically within its base on the dorsal side. A single nerve trunk is given
off which ramifies throughout the tissue of the foot in a most complete manner
Both byssus and byssal gland are absent, neither is there any trace of an otoeyst—
the latter a peculiarity shared with Solevomya and a few other Lamellibranchs.
The inner surface of the pedal sucker appears to be homologous with the locomotor
region of the foot in Margaritifera : whether the byssal gland is also represented by
the interior of the sucker cannot be decided until we obtain embrvological light upon
the subject.
HORNELL—ANATOMY OF PLACUNA 59
PALLIUM OR MANTLE.
The general disposition of the mantle has already been noted. We have seen that
its borders are without sutures between themselves save for a short distance along the
hinge line, where the two pallial lobes unite over the extreme dorsal region of the body.
The margins of the lobes are otherwise absolutely free ; they show no trace of siphons,
neither are the branchie connected laterally with the inner surface of the mantle
either by organic fusion as in Anodonta, or by ciliar suture as in Margaritifera
vulgaris.
Three regions compose each pallial lobe—a central, a distal or muscular, and a
marginal, all comparable and closely related in structure and position with the similar
regions seen in the mantle of Margaritifera.
The central pallial area extends from the mid-dorsal line to the irregular and
imperfect pallial line where are inserted the radiating pallial muscles. The junction
with the distal area is not demarcated clearly as in the case of Meleagrinide. The
greater portion of the central pallial area is adherent to the visceral mass on both sides,
and a comparatively small part is free.
In both cases the mantle is thin and transparent, except where in the right
mantle masses of reproductive tissue and portions of the alimentary canal penetrate
and ramify in its substance.
Where free from the complication of adhesion to the visceral mass, or of
penetration by glandular and other organs, the tissue consists of two parallel sheets of
epithelium connected by an excessively fine network of connective tissue.
The distal or muscular region of the mantle is transparent save where masses of
black pigment occur in the external superficial tissue. The whole of its external face is
covered with secretory epithelium similar in histological structure to that upon the
exterior of the central pallial area. Below this outer epithelium occur a few scattered
glandular cells of large size, and containing slightly refractive granules.
Strongly ciliated epithelium lines the inner surface of this pallial region and
subserves the double purpose of assisting in maintaining a steady indraft of water into
the branchial chamber and in ridding the pallial surface of sediment brought by the
incoming water current. In M. vulgaris a distinct narrow marginal ciliated “path”
exists, along which pellets of sediment are propelled to the exhalent region; here
there is no such path—the whole ciliated surface acts this part. In a newly-opened
living individual tiny pellets of mud may be seen at several points on the general inner
surface being propelled posteriorly, to be swept from the body by the current of the
excurrent stream of water from the gills.
Histologically there are present the usual characteristics of this region as seen in
other Lamellibranchs—a filling of connective tissue fibres in which radiate fan-shaped
muscle bundles, the trunks and bundles of the pallial nerve plexus and a great network
60 OKHAMANDAL MARINE ZOOLOGY REPORT
of irregular communicating blood spaces. One of these last is developed into a well
defined and most conspicuous channel, the anterior ventral pallial sinus (fig. 19,
Sn.pall.av.), which, arising close to the posterior extremity of the gills by the
confluence of several smaller sinuses, passes forwards and upwards, adjacent to and
parallel with the course of the axes of the gills, to near the base of the foot where the
sinus opens into the common branchio-cardiac trunk. This great sinus is accompanied
through the greater part of its course by a nerve trunk and by a rich black
pigmentation in the epithelial cells of the outer surface. It receives branch vessels at
intervals from the substance of the mantle and the main ones are also outlined in
pigment.
It is noteworthy that the course of this pallial sinus and its main feeders, together
with those of the principal radial bundles of pallial muscles, are clearly impressed
as well-defined shallow grooves upon the inner surface of each valve.
In the mantle fold on the right side of the body a further complexity is
introduced into this region by the necessity forced upon it to provide accommodation
for the enormously developed pyloric caecum (C.s¢.c.) and its huge crystalline style
(C.st.), which, with a narrow enveloping sheath of genital tissue, penetrates the pallial
tissue in a great semicircle parallel with and slightly dorsal to the median pallial sinus,
ending a short distance anterior and ventral to the anus. Its termination coincides
with the position of the free dorsal edge of the right branchial mesentery.
As in other Lamellibranchs, each pallial lobe terminates in a thickened muscular
rim or margin pleated longitudinally into three folds throughout the whole length
(fig. 32). The two outer folds form the true pallial margin; they project outwards in
the same plane as the shell, while the third or inmost fold, the velum or “ veil,” lies at
right angles to the other two and as an inwardly directed narrow shelf of tissue on the
inner side of the mantle. When the valves are slightly open these velar folds, with
their delicate digitate processes, extend inwards towards each other in the middle line
and thus form a highly sensitive strainer guard, ever ready to give instant warning of
contact with any would-be intruder.
Of the two folds forming the true pallial edge, the outer may be called the
secretory fold, the inner the sensory. The former lies in contact with the growing
edge of the valve kept tightly adpressed thereto by a film of cuticular membrane, the
periostracum or epicuticula (periost.). This arises from the secretion of a layer of
glandular epithelial cells lining the base of the groove separating the outer from the
inner fold of the pallial edge. Fig. 32 shows how this structureless membrane curves
outwards and is reflected over the free edge of the shell, firmly attaching the secretory
marginal fold thereto. In this animal this function—the binding or securing in place
of the secretory fold to the margin of the shell—appears to be the sole duty of the
periostracum, as it appears not to persist over the general surface of the valves in adult
individuals,
HORNELL—ANATOMY OF PLACUNA 61
The sensory fold between the velum and the secretory fold of the mantle edge is
very similar in general appearance to the velar edge, but is furnished with more
numerous simple unbranched digitate processes. These are highly contractile and
extremely sensitive.
Along the base and in the connective tissue filling of the thrice-folded pallial
margin runs a peripheral blood-vessel, the pallial artery; with it, in intimate
association, is a strong nerve trunk, giving off a multitude of fibrils to the secretory
and tactile areas. The ultimate twigs of the pallial muscles penetrate to this margin,
enabling retraction to be effected upon any irritation experienced by the sensory cells
in the vicinity. The greater the rapidity of retraction the greater the immunity from
damage by predatory fishes and other enemies. Large spaces or sinuses are very
conspicuous, penetrating the loose connective tissue which is freely developed close to
the mantle edge.
We have already noted that the continuous growth of the periostracum functions
to keep the margin of the mantle attached to the edge of the shell. The mantle is
further kept in position lining the valves by the adhesion occasioned by the formative
secretion of the cells of the external surface. Violent contraction of the pallial muscles
impairs these two mechanical adhesions by dragging the mantle edge away from the
margin of the shell, while the distension and turgescence of the mantle with blood
coincident with relaxation of the pallial muscles permits the contracted mantle to
re-spread or re-expand over its normal and full area, when a short period of quietude
re-establishes mechanical adhesion with the shell by new periostracal growth and
surface secretion.
It is important to note the importance which the right mantle lobe assumes over
the left in this mollusc, through the penetration and lodgment within it of the bulk of
the reproductive gland, the great pyloric caecum and a considerable portion of the
rectum.
PigMENTATION.—The development and distribution of pigment in the mantle is
very variable. In some cases practically the whole of the external surface is covered
with black pigment. In other instances the colouring matter is less extensively
developed; bands of pigment, however, invariably follow the course of the great
median pallial sinus and its main branches, as well as that of the more important of
the pallial muscle bundles. This black pigmentation is limited to the mantle, where
it occurs in the superficial epithelial cells. Nowhere else is there any true
pigmentation—the inner surfaces of the mantle and all the folds and processes of the
mantle edge are colourless, a condition the reverse of what is seen in the true pearl
oysters (Margaritifera spp.), where the mantle edge and the inner surface of the
mantle are often profusely pigmented and where the outer surface of the mantle lying
in contact with the nacre of the valves is invariably free from even the slightest
pigmentation. The reason is not far to seek, It has already been noted that Ceylon
62 OKHAMANDAL MARINE ZOOLOGY REPORT
pearl oysters (M. vulgaris) found living in shallows—say under one fathom in depth—
are usually much more brightly coloured with black and orange over the mantle, gills
and foot than those from depths of seven to eight fathoms. We also know the general
tendency of continued exposure to bright light to encourage the development of
pigments, usually dark in hue. Hence, as P. placenta is essentially an inhabitant of
shallow waters, where light is intense and long-continued, we can readily understand
the cause of extreme pigmentation of the mantle. As to the less obvious reason for it
being on the exterior of the mantle instead of the interior, as in M. vulgaris, this is
most probably due to the transparency of the valves. In the true pearl oysters the
valves are opaque—the sun’s actinic rays cannot penetrate their substance—hence
no protection need be given from this aspect to the delicate organs and tissues,
nerves especially, lying beneath. Protection has, however, to be given against light
entering between the open edges of the shell, hence development of pigment on the
gills and the inner surface of the mantle.
In Placuna the valves are transparent, and, as light passes through them without
difficulty, protection must be provided against light impinging directly on the mantle
from the exterior—effected, as we have seen, by a development of black pigment
either generally over the exterior of the mantle or restricted to the course of the main
trunks of the pallial nerve plexus.
THE MUSCULATURE.
Like the pearl oyster, P. placenta is monomyary, a single adductor, the posterior,
being present. The other muscles are relatively weak, and consist of :—an unpaired
weak levator of the foot, a similarly unpaired weak pedal retractor, an imperfect
orbicular pallial muscle, branchial cords, and the heart or cardiac muscle. (The last will
be treated of separately when describing the vascular system.)
The Appuctor Muscie of the shell is situated sub-centrally, stretching trans-
versely from valve to valve midway between the anterior and posterior limits of the
shell, but slightly nearer the dorsal than the ventral margin (fig. 4, Add.). It is the
only large muscular mass in the body, and is by far the most important. The outline
in section is circular, while the diameter in specimens of 14 cms. long is about 2°3 cms. ;
the length is inconsiderable in consequence of the extreme lateral compression of the
valves. It lies ventral to the visceral mass ; the surface of the dorsal half is closely
embraced by the renal organ. Along the posterior border runs the terminal section of
the rectum, while upon the antero-ventral curvature rests the parieto-splanchnic
ganglionic mass.
Even a casual observation in the living condition reveals the fact that this muscle
is not homogeneous; in preserved specimens the fact is emphasized ; two distinct
regions are visible to the naked eye—a posterior and median, and an anterior and
HORNELL—ANATOMY OF PLACUNA 63
larger surrounding the former except on the posterior aspect. The posterior section
may be said to be sunk in the anterior one (fig. 9).
The posterior component in most preserved specimens retains a darker colour than
the other and larger region ; it extends forwards from the posterior margin of the mass
for about three-fourths of the diameter of the entire adductor, and so is covered
dorsally and ventrally by arm-like prolongations of the anterior region. Little
histological difference can be noticed between the elements of the two sections except
that the fibres of the anterior appear rather finer, and are aggregated into larger and
more densely compacted bundles than is the case with those of the posterior. The
muscle bundles round the periphery are large and wedge-shaped in section; those of
the centre small and rounded. Both the component masses are freely permeated with
blood spaces more numerous, however, in the hinder section of the muscle. In
Pecten the fibres of the anterior component show an appearance of striation ; here
no indications of this could be perceived in sections—the fibres of both regions
appear quite smooth.
The blood supply is derived from the posterior limb of the aorta through one
artery entering the adductor on its upper surface and by three others entering between
the halves of the parieto-splanchnic ganglion (fig. 15). Innervation is directly from the
ganglion just named, whence two trunks arising side by side from the two halves of the
mass pass immediately into the substance of the muscle, dividing as they go into small
twigs (fig. 10, N.add. and fig. 29, Par.sp.g.).
The Levator Musc ie of the foot is weakly developed in Placuna; it consists of a
narrow band of muscle fibres inserted obliquely in the left valve immediately posterior
to the ventral extremity of the anterior hinge tooth (fig. 19, Lev’.). Thence the fibres
pass vertically downwards, spreading laterally as they approach the base of the foot,
where they blend with the intrinsic pedal muscle fibres. A similar reduction of the
pedal levators to an unpaired weak bundle inserted in the dorsal region of the left valve
is met with in Anomia.
The Pepau Rerractors are similarly reduced in Placuna to a single fairly stout
bundle, which arises from the ventral part of the muscular base of the foot and passes
downwards to the left side of the dorsal surface of the adductor, where it finds insertion
upon the left valve (fig. 31). In Placwna this muscle has little importance owing to
the absence of a byssus; large development of the pedal retractors appears to be
correlated with special development of a byssal organ. As examples we have two
powerful retractors present in Margaritifera vulgaris, where a many stranded byssus
exists, while in Anomza, where the byssus undergoes modification into a great calcified
organ, these muscles are still larger and more important, with the unique peculiarity of
being both inserted in the left valve in like position as the single one in Placuna. In
view of this special function these muscles might with greater propriety be termed
byssal, and not pedal retractors.
64 OKHAMANDAL MARINE ZOOLOGY REPORT
The intrinsic muscles of the foot form an extremely complex system, comparable
in general arrangement with the musculature of any mobile liguliform muscular organ.
Towards the base the fibres in large measure radiate outwards to form a somewhat
laterally compressed discous base. In the cylindrical trunk region of the foot the
muscle fibres run in every possible direction; many run longitudinally, some run
circularly, others radiate outwards, and the remainder interlace in apparently hopeless
confusion. Circular and radiating muscle fibres preponderate in the sucker-like free
extremity ; the rim is capable of closure as by a sphincter muscle.
Few other intrinsic muscles are to be found in Placuna ; the principal are the
small paired cylindrical muscle bundles which traverse the axes of the branchice
longitudinally in the floor of the efferent branchial vessels (fig. 24).
Slender muscle fibres also pass down the interior of the individual gill filaments,
enabling them to be retracted to some slight extent.
The OrpicuLar Patt1aL Muscie is composed of a small and variable series of
loosely compacted fan-shaped muscles radiating outwards to the mantle edge from
some four to six insertion centres of varying size and shape grouped in a roughly
semi-circular manner around the ventral half of the adductor muscle. The dispo-
sition of these centres (and of the corresponding scars which their insertion imprints
upon the inner surface of the valves) lacks alike the regularity of disposition seen in
the Meleagrinide, or the continuity characteristic of Cardiwm ; the insertion scars are
extremely faint on the valve surface in Placuna, while in a dissection the insertion
centres are difficult to trace owing to their irregularity and to the layer of repro-
ductive tissue which accompanies and masks them. One of the most frequent
dispositions is where there are two large insertion centres anterior (M.ins.a.) and
two small ones posterior (M.ins.p.) to the base of the adductor, with a long and
extremely narrow band insertion skirting and apparently fused with the ventral
edge of the adductor at its insertion in the valve. Fig. 19 graphically depicts
the relative positions and forms of these centres, as well as the course and branching
of the ill-defined fans of fibres which radiate towards the pallial margin dividing
into finer and finer branches as they go.
From the radial course pursued by these bundles, it follows that they are attached
to the shell at a very acute angle. Their whole course lies in the filling of connective
tissue forming the thick middle layer of the distal region of the mantle. Many of the
branches anastomose, and as they approach the pallial edge they divide into two sets
of fibres, one passing to the inner aspect of the margin to provide for the movements
of the velum, the other to the outer margin to serve the two folds of the true pallial
edge. Many of the principal of these radial muscles impress a record of their course
and branching in corresponding shallow but distinct groovings upon the inner surface
of the valves.
HORNELL—ANATOMY OF PLACUNA 65
THE ALIMENTARY CANAL.
The alimentary canal in Placuna consists of a slit-like asymmetric mouth,
a rather long and wide cesophagus, a capacious stomach surrounded by a well
developed digestive gland, an enormously developed pyloric caecum, a short intestine
making a single visceral loop, and a short and slightly curved rectum ending in
an anal opening in the centre of a broad and widely everted membranous collar
(fig. 14).
The mouth is a long slit-like aperture situated vertically in a deep cleft
between two delicate membranous folds—the lips or labia—to the right side of
the median plane of the body at about midway between the base of the foot and
the dorsal margin of the body. The mouth is concealed by the labia. These,
which in typical Lamellibranchs are disposed transversely to the vertical plane of
the body, here follow the asymmetery of the mouth; what is morphologically the
lower one in Placuna bounds the mouth along the left side; the upper lies to
the right of the mouth. At each angle of the mouth the labia close in and pass
into the labial palps. The labia are smooth on both surfaces; the labial palps are
smooth on the faces turned away from each other, while on those turned to one
another they are furrowed with many fine transverse ciliated furrows of ordinary
typical form such as seen in Muargaritifera. The free edges of the labial palps
face forwards (anteriorly) while the posterior margins are attached to the front
of the visceral mass. Those of each pair are also closely approximated at their
insertion into the visceral mass, forming thus a very narrow deep-walled gutter
along which food pellets are propelled by ciliary action from the anterior extremity
of the gills to the corners of the lips and thence into the mouth.
Unlike the labia which are thin and membranous, the palps are considerably
thickened with a filling of connective tissue. They are unusually long, reaching
well below the base of the foot. The ridges are of the same form as seen in
Margariifera and densely ciliated.
The mouth leads into a long and rather wide ciliated cesophagus, slightly
compressed laterally, which curves posteriorly and ventrally and opens abruptly
without change of calibre into the anterior dorsal region of the stomach.
The stomach is relatively capacious and occupies a sub-central position in
the visceral mass. In form it is irregularly ovoid and much compressed laterally ;
its long axis lies somewhat obliquely dorso-ventrally in such fashion that the
ventral part is directed slightly anteriorly, while the dorsal exhibits a corresponding
backward inclination.
Several well marked depressions occur in the walls of the stomach, so that
we may roughly divide it into four subsidiary chambers (wide fig. 29); the first
is shallow and lies dorsal and anterior; into this the cesophagus opens. The second
66 OKHAMANDAL MARINE ZOOLOGY REPORT
is dorsal and posterior, narrow and cecal in appearance and reaches a higher level
dorsally ; the third is posterior and the fourth ventral and pyloric. The two latter
chambers are very distinctly defined ; the posterior one, which may be termed the
biliary chamber, is a deep branched crypt pushing its branches deep into the
substance of the digestive gland from which it receives numerous large bile ducts.
In the floor of the pyloric chamber two openings of about equal size are discernible ;
the one leads into the intestine, the other into the pyloric cecum (C‘st.c.). From
the latter opening the conical proximal end of the crystalline style (C.st.) projects
some distance into the stomach; a bolus-like mass of partially digested material
may often be seen agglutinated upon this stylar projection.
This cameration of the stomach has the effect of considerably increasing the
surface area; in Placuna the stomach appears to be developed at the expense
of the intestine.
The whole of the stomach is lined with ciliated epithelium, exhibiting great
variability in the height of the cells. Usually these cells reach their greatest
development on and over the permanent ridges. A delicate and easily detachable
gelatinous layer—the fléche tricuspide (fig. 23, Fl.tv1.)—invests a great part of
the stomach wall ; wherever this layer is well developed, there we find the epithelium
greatly elongated. This peculiar investment is particularly thick over the central
anterior wall of the stomach, where it is intermittently adherent, dipping down
between the ridges and pads which corrugate the inner surface of the stomach.
No structure save a slight lamination can be detected; it is perfectly clear and
colourless—from its behaviour under reagents it appears closely related in composition
to the crystalline style.
The stomach is almost entirely surrounded by the digestive gland. Only over the
right aspect and at the extreme dorsal extremity does the investment fail; in these
regions, owing to the laterally compressed form of the animal, the wall of the stomach
is separated from the mantle only by thin discontinuous patches of glandular tissue.
The “liver,” or digestive gland (D.gi.), is a large, dense, acinose gland of sage-
green colour, forming the greater part of the tissues of the visceral mass and forming a
nearly complete investment to the stomach, cesophagus, and the proximal halt of the
intestine. Superficially, a considerable portion is covered in its turn by a thin sheet
of reproductive tissue.
Bile ducts emptying the secretion of the digestive gland into the stomach are
numerous (fig. 29, D.gl.d.). At least eight terminal duets can be traced; they are the
following :—
(a) The dorsal duct opening high up in the postero-dorsal chamber.
(b) The anterior duct leading from the anterior region of the liver into the
antero-dorsal chamber; and
HORNELL—ANATOMY OF PLACUNA 67
(c) A series of six which open into the well-defined, deeply indented biliary
chamber in the hinder wall of the stomach. These ducts come from the
posterior and ventral regions of the digestive gland.
The ciliated epithelium of the walls of the stomach is continued a considerable
distance along the larger bile ducts (see Plate V., fig. 28). The gland proper is
composed of dense masses of secreting alveoli, lined with large cells differing
considerably in size and shape. Details are practically identical with those of such
other Lamellibranchs as Ostrea, Margaritifera and Cardium, and therefore do not call
for further detailed notice.
The CrysraLuine Sty tz has already been noted as projecting somewhat into the
pyloric region of the stomach. Its sac, the pyloric cecum, is wholly free from any
connection or fusion with the intestine along its entire course, thereby agreeing with
those forms typified by Mytilus, Donaxz, and Anomia, as well as with such gastropods
as Pterocera, Trochus and the Fissurellide.
From their respective proximal ends the pyloric cecum and intestine immediately
diverge, the former pursuing an anterior direction, while the latter in the first part of
its course curves posteriorly.
The pyloric cacum (C.st.c.) bends to the right and penetrates the right mantle
almost immediately after leaving the stomach, and close to the anterior apices of the
gills. It then passes forwards and downwards just in front of the adductor muscle,
turns backwards at its antero-ventral curvature and then passes posteriorly parallel with
and to the dorsal side of the pigmented line of the median pallial sinus (fig. 13). The
blind termination coincides closely with the level of the normal position of the posterior
apices of the gills—indeed, the curvature of the pyloric caecum runs parallel with the
gills throughout their entire length. From its mid-length to its termination the sac
narrows very gradually. In preserved specimens, which naturally suffer from muscular
contraction, the sac assumes a wavy or slightly sinuous course; in the living state the
sac lies in a single unbroken deeply bow-shaped curve. Throughout its course the
cecum is embedded in an investing covering of reproductive tissue, of which a peculiar
spongy tissue constitutes the major portion. In section the sac is perfectly circular
throughout its length ; its lumen is entirely filled by the colourless glassy substance of
the crystalline style. In serial section of fixed material the style exhibits great
shrinkage and occupies but a small portion of the cecal cavity. No structure is
discernible save a faint concentric lamination, giving the impression that the style is
formed by the deposition of successive concentric layers of secretion.
The inner surface of the stylar sac is ciliated like all other parts of the alimentary
canal, but the cilia are quite different from the ciliation of the other regions. They
are characterised by being markedly strong and densely set; they are extremely stiff
in appearance and are all of even length (fig. 25).
G
68 OKHAMANDAL MARINE ZOOLOGY REPORT
In their enormous relative length the crystalline style and its sac attain a
development most remarkable—a development almost unique among Lamellibranchs.
Only in Anomia do we find the cecum so extremely elongated relatively to the other
sections of the alimentary canal. In Anomia we may also note that the inner
curvature of the caecum is turned away from the adductor, so that the cecal or distal
termination is near the anterior edge of the mantle, whereas in Placwna the curvature
of the caecum embraces the adductor and its distal end is situated a short distance
from the anus.
Regarding the function of the crystalline style, I am fully convinced from a study
of this organ in the present species and in the pearl oyster (M. vulgaris)’ that Barrois’
view is correct, that the style is a cuticular secretion which serves to invest diatoms,
sponge spicules and the like with a viscous coating which will secure the intestinal
walls from damage through abrasion. The extreme length of the style in Placuna
shows it to be of extreme importance in the economy of this mollusc; it is to be
correlated with the particular habitat favoured—muddy bottom and slightly brackish
water—both conditions which are well known to be most favourable to the growth and
multiplication of diatoms, many of which, like Navicula, have sharply pointed siliceous
tests that would abrade the delicate wall of the molluscan intestine unless some
viscous investing substance were provided to form them into bolus-masses and serve
as a lubricant during the passage through the gut. The stomach contents of Placuna
bear this out; there is a predominance of diatom tests over other recognisable
organisms—a much greater relative abundance than is seen in the case of the stomach
contents of the pearl oyster.
The intestine arises from the lowermost section of the stomach, close to the mouth
of the pyloric caecum and somewhat to the right side. It passes for a short distance
posteriorly and ventrally, and then, just anterior to the heart, it turns in a dorsal
direction, curves forward, and then passes downwards when near and at the level of the
biliary chamber of the stomach. This descending limb of the intestine crosses the
ascending limb on the left side, thus completing a single simple intestinal coil largely
within the substance of the liver. For some little distance, however, the wall of this
coil comes close to the surface of the visceral mass, and is obvious to the naked eye
as an elongated clear patch. The ventral curve of the intestinal coil lies close to and
just anterior to the heart.
From this spot the intestine, which may now he differentiated as the rectum,
passes in a fairly straight course downwards and backwards along the postero-dorsal
curve of the adductor, then turns more distinctly in a posterior direction, bends slightly
upwards, and opens on a flask-shaped anal papilla surrounded with a widely-everted
membranous collar, and situated immediately dorsal to the distal extremities of the
gills. On the upper or postero-dorsal aspect of the rectum is a cecal prolongation of
? “Ceylon Marine Biological Reports,” part ii, p. 78, Colombo, 1906.
HORNELL— ANATOMY OF PLACUNA 69
the renal organ readily distinguishable even to the naked eye by reason of the dark
colour of its glandular tissue.
The intestine is lined throughout its entire length with ciliated epithelium, and its
absorbing area is considerably increased by the presence of a typhlosole or longitudinal
ridge extending to the anus from about the first fifth of the intestine (fig. 26, Ty.).
Anteriorly the typhlosole when seen in section is somewhat mushroom-shaped, a
narrow neck bearing a button-shaped “head.” It is much less prominent and less
expanded than in Margaritifera vulgaris in the corresponding region. Posteriorly
it is even simpler, consisting of a simple parallel sided fold projecting into the
interior of the rectum to about its semi-diameter.
In common with Anomia and Arca, the rectum is in no way attached or connected
with the ventricle of the heart. It passes quite free on the anterior and ventral
aspects of the heart.
BRANCHIAL SYSTEM.
The branchiz are long and greatly curved, four delicately graved scimitars lying
within the protection of the free portions of the mantle (fig. 4). From between the
ventral edges of the labial palps the branchie curve first downwards and then
backwards to a point just ventral to the anal aperture, where all four close together
somewhat abruptly to a sharply attenuated conjoint free tip. In their course they
keep parallel and a little inward to the mantle edge, the inner curve half circling the
adductor muscle being suspended by two deep curtains of thin tissue, the branchial
mesenteries, which hang from the renal tubes in the first part of their course, and in
the hinder region from the mantle close to its line of junction with the anterior and
ventral edges of the adductor muscle.
The four branchize or gills are disposed in pairs on either side of the body. As
each pair constitutes a ctenidium, each branchia or gill is morphologically a hemi-
ctenidium.
The ctenidia show comparative simplicity of structure. There is the usual
longitudinal vascular base or axis along the inner margin of each ctenidium, upon
which, on the outer face, are inserted two parallel series of long and delicate tubular
outgrowths, the branchial filaments.
All the filaments being inserted at right angles to the axis on the outer face,
their initial direction is outwards and towards the nearest section of the pallial margin.
At a common distance from the vascular axis, filaments in each series change their
course—those of the outer, or external, scries are reflected or folded outwards upon
themselves in the form of a V, with closely approximated wings, while those of the
internal series are similarly V-folded, but in their case the folding is inwards
(figs. 12 and 24).
Each series of filaments constituting a branchia is now seen to be divisible into
G 2
70 OKHAMANDAL MARINE ZOOLOGY REPORT
two lamella, the proximal or direct (fig. 12, D.br..), where the course of the filaments
is directed outwards, and the distal or reflected (f.br./.), where they are folded
inwards,
The reflected lamella of the external hemi-ctenidium is rather narrower than the
direct, due to the fact that this lamella, close to its distal margin, is again folded
outwards upon itself to constitute a very small fifth lamella, a peculiarity very rare and
seen only in the closely-related genus Anomia. In depth this accessory lamella (figs. 4
and 12, Br.acc.) is equal to the difference between the depth of the direct and
reflected lamella. As in Anomia, the outer reflected lamelle are free; there is no
trace of conerescence with the mantle either by organic fusion or by ciliary junction.
Along their whole length the distal edges of the reflected lamella of the inner branchial
plates unite along the middle line in weak organic union, reinforced by a short ciliary
concrescence on the ventral side of the organic fusion (fig. 12, Ctyj.), thus combining
two distinct forms of concrescence and suggesting that the original form of union was
entirely by ciliary concrescence as seen to persist—save for the merest thread of organic
fusion—in the median branchial junction of the pearl oyster. The union along this
median branchial line is continuous, fusing the terminals of all the filaments from the
inner reflected lamella of each ctenidium into one continuous band of tissue and
serving as a median support to the inner branchie.
The general arrangement of the filaments is of the Filibranch type. Except for
the median branchial fusion, the filaments have no organic union between themselves ;
they lie perfectly free along their whole course save for a series of lateral interfila-
mental ciliated junctions just within the crest of each branchia where the direct
filament passes into the reflected. At this place each filament presents an elongated
swelling on each latera] face in such a way that the approximation of the two swollen
opposing faces of the adjoining filaments reduces the spave between them very
considerably, a space bridged over by stout interlocking cilia borne upon each lateral
swelling, thus constituting a ciliated disc (fig. 33). This development of ciliated discs
along the free edge of each branchia is noteworthy and marks an advance in
specialisation beyond what we find in Anomza, where true ciliated discs are wanting.
As a consequence the branchial framework in Placuna has greater rigidity than in
Anomia, the filaments less easily dissociated.
The vascular axis of each ctenidium, as before noted, is suspended from the mantle
by a mesentery (figs. 4, 12, Br.ms.), extending from the base of the palps to the
postero-ventral curvature of the adductor muscle.
The narrowed anterior apex of cach gill is attached between the divergent ventral
edges of the palps of its respective side. ‘The extreme apex of the gill lies in the
palpal gutter that marks the line of junction of the outer and inner palps, so that fuod
particles passed to the anterior extremity of a ctenidium are caught by the palpar cilia
and propelled upwards along this palpar gutter to the mouth.
HORNELL—ANATOMY OF PLACUNA 71
In most Lamellibranchs the anterior extremities of the two ctenidia are separated
for some distance by the base of the foot and the adductor portion of the visceral mass.
In Placuna the palps extend to such a distance ventrally that the anterior apices of
the gills are attached well below the foot and on a Jevel with the ventral edge of the
visceral mass (fig. 12). Hence the inner margins of the gills meet in the median line
immediately ventral to the palps; save for this inconsiderable divergence the two
etenidia run conjoined throughout their full length. Anteriorly the pallial mesentery
is short ; it widens quickly, and for the major portion of its course is from two to three
times the depth of the gills. In its posterior third it narrows slightly, while the
combined terminal portion of the gills is free from its attachment for a short
distance.
The axis of each ctenidium is hollowed out into a large irregularly tubular cavity,
the efferent branchial vessel (Br.eff.), which receives purified blood from the filaments
to convey to the trunk leading to the heart. In the floor of this sinus on either side
runs a short muscular cylinder or cord, continuous from the anterior to the posterior
apex of the gill) These two muscular cords function as branchial retractors, shortening
the gills upon contraction and drawing them inwards, an action in which they are
assisted by fine muscle fibres which radiate outwards within the branchial mesenteries.
Unlike the typical arrangement of parallel afferent and efferent vessels within the
branchial axis, no second or afferent vessel is to be seen in the gill axis of Placuna.
Such vessel is here represented by a well-marked longitudinal blood trunk running in
the mesentery at some considerable distance from its base or attachment (figs. 4, 12 and
22, C.br.aff). Connection between this vessel and the branchial filaments is effected
through the intermediary of a network of sinal spaces (fig. 4, Br.ms.pl.) in the tissue
of the mesentery ; the arrangement is practically identical with that present in
Anomia.
To understand the significance of this departure from the more normal arrangement
as seen in such forms as Margaritifcra and Cardium, it is necessary to recognise the
mesentery as morphologically the proximal portion of the primitive ctenidial axis, a
portion which has undergone a profound change of form; the conversion of a simple
vascular ridge along the inner side of the axis into a deep sheet of tissue has induced
a change from a system where extremely short channels connect a proximate afferent
trunk with the individual filaments, to one where a complex and extensive network
of ill-defined sinal spaces is intercalated between the filaments and a far removed
afferent trunk. It would seem that the short afferent branches of the one have in part
been modified into this peculiar sinal plexus.
The effect of this mesenteric development is to add materially to the blood-
purifying area; it has a distinct accessory branchial function, and must assure a partial
oxygenation of the blood stream prior to it passing into the gill filaments, thereby
facilitating their branchial function. The very extensive development of the
72 OKHAMANDAL MARINE ZOOLOGY REPORT
mesenteries is to be correlated with the little depth characteristic of the gill lamelle in
Placuna.
The histological structure of the filaments is essentially the same as in Anomea
and other forms where the branchie exhibit little specialisation. Each filament consists
of a single layered cylinder of cells supported on a delicate basal membrane. In section
the cylinder is seen to be somewhat club-shaped (fig. 34); the broader end morphologi-
cally is the ventral side, the narrower the dorsal. The cells of the former portion are
very large, those of the narrow end exceedingly small and unciliated.
The majority of the cells on the broader portion of each filament are ciliated ;
certain stable distinctions in the distribution and character of this ciliation divide
the ventral or exterior part of the filament into longitudinal tracts. A transverse
section of a filament shows these to consist of—(a), a wide frontal ciliated tract
comprising all cells facing directly outwards ; the cilia on these cells are particularly
short (F.c.); (b), at the antero-lateral corner on either side of the frontal tract,
a single large cell bearing many much elongated cilia (A.lc.), and containing a
specially large nucleus; (c), a narrow bare region on either side of the filament,
bounded outwardly by the ciliated “corner-cell,” and on the inner aspect by the
lateral cilia mentioned next; (d), a lateral ciliated tract (L.c.) several cells wide
bearing long cilia, and (e), a few cells between the lateral ciliated tract and the
margin of the small cells of the dorsal (internal) section of the filament. Fig. 34
makes clear this disposition of the ciliated tracts.
Beneath the epithelium of the filament a layer of connective tissue lines the
cavity ; for the most part this layer is thin, but within the narrow dorsal section
of the filament it thickens and strengthens into two stout longitudinal skeletal
bands (Sk.b.) to constitute a supporting framework against the collapse of the
filamental tube.
As in Anomaa, the cavity of the filament is divided into two somewhat unequal
channels by an extremely delicate septum (Sep.) uniting the two skeletal thickenings
towards the middle of the filament and situated rather nearer the narrower than
the broader face.
The smaller or dorsal of these small vessels serves as an afferent (A.ch.), the
larger or ventral as an efferent blood channel (#.ch.) through the filament.
At the distal end of each reflected filament these two channels communicate,
the afferent passing over into the efferent, as the dividing septum does not extend
quite to the extreme end of the filamental cavity.
BRANCHIAL CIRCULATION.—As a consequence of the simplicity of the branchial
plan, the blood circulation is for the most part of an equally primitive type.
Impure blood from the body generally, after having bathed the tubules and pouches
of the renal body, is collected into two well-defined vessels, the afferent branchial
sinuses (figs. 4 and 15, C.br.aff:), one of which lies within each mesentery, entering
HORNELL—ANATOMY OF PLACUNA 73
it close to the parieto-splanchnic ganglion. ‘The vessel first passes outwards for
about one-fourth the depth of the mesentery and then divides into a short anterior
branch proceeding towards the anterior apex of the ctenidium and a long posterior
branch which passes to the posterior extremity. Both branches keep well to the
inner side of a line that would divide the mesentery into a proximal and a
distal half.
From each of these vessels a large number of branches are given off which
divide and ramify throughout the distal section of the mesentery to form an
anastomosing network of sinal spaces (Br.ms.pl.). Along the outer margin of
this plexus and fed by it, a series of regularly disposed and slightly swollen
“capillaries” arise, which pass blood into each branchial filament. This current
of blood flows outwards within the smaller or afferent of the two parallel cavities
within the filament, returning by the larger or outer tube to empty into the wide
efferent vessel running along the ctenidial axis (figs. 4, 12, and 24, Breff.). This
vessel carries the blood forwards and upwards and is directly continuous with
a short well-marked wide vascular trunk—the common efferent or branchio-cardiac
vessel (fig. 24, Cbr.eff), running at right angles to the anterior portion of the
branchial axis and connecting the anterior extremity of the ctenidium of its
respective side with the auricle of the same side, appearing indeed as an anterior
prolongation of the latter.
Oxygenation takes place partly during the flow of the blood through the
mesenteric sinal plexus, partly during the flow through the branchial tubules.
Each ctenidium derives its nerve supply from a trunk which arises from the
parieto-splanchnic ganglionic mass, and which runs within the mesentery some
distance from and parallel with the ctenidial axis (figs. 10 and 11, N.br.).
Functions oF THE Brancut#.—Apart from the oxygenating function which
in Placuna as in Anomia is shared by the branchial mesenteries, the gills of
Placuna serve two well-marked mechanical functions, (a) the capture of food particles,
and (b) their conveyance to the mouth. The rhythmic lashing of the cilia clothing
the outer faces of the filaments causes an indraft of water into the shell which not
only serves to oxygenate the blood passing through the branchial tubules and
mesenteries but ensures a continual stream of food particles being brought in.
The close approximation of individual filaments and the fringes of cilia along their
sides then come into play to intercept and strain out these particles, which are
then caught up by certain cilia and propelled first to the crest (ventral edge)
of the branchiz and thence along this crest direct to the labial palps and
mouth.
To properly perform these varied functions the cilia of the filaments have under-
gone specialisation and peculiar localisation. We have noted in each filament four
distinct ciliated tracts marked off by the length and disposition of the cilia, (a) a broad
74 OKHAMANDAL MARINE ZOOLOGY REPORT
frontal band of short cilia, bounded by (b) a narrow band of long lashing cilia at each
corner, (c) a lateral band of equally long cilia, and (d) close to the crest of the gill a
ciliated disc on each lateral face of the filament.
The function of the last-named is to keep the filaments in position, to prevent
them fraying out and becoming displaced. The short, stiff cilia of the “discs”
interlock most securely and provide very serviceable unions between the filaments
(fig. 33). The cilia of the lateral bands are not localised to one section of the filaments
like the “discs,” but stretch from end to end of the filaments; they are very much
longer and have very much less intimate union—those from opposing faces appear to
lightly interdigitate only towards their extremities. Besides the support they provide
by this interlocking, slight and scarcely adequate though it appear, these cilia
function as the actual strainers of the food particles, and this may be considered their
particular duty.
That of the lashing cilia of the corner cells is well known—it is to create and
maintain the incurrent water-stream.
Finally, coming to the short cilia (F’c.) that clothe the whole frontal (ventral)
face of each filament, observation upon the living animal leads me to believe that the
special function here is the propulsion of food particles outwards to the branchial crest,
where, as in the pearl oyster, | have been able to recognise a ciliated pathway leading
directly to the base of the labial palps.
Thus when a diatom or an algal spore is intercepted by the sieve formed by the
interdigitation of the long cilia of the lateral bands it is thrown out upon the broad
frontal path of short cilia which pick it up and propel it swiftly to the gill crest, where
the cilia of the crest pathway catch it and propel it at right angles to its first course
onwards to the anterior apex of the gills, where it is surrendered to the care of the
palps.
THE VASCULAR SYSTEM.
The vascular system of Placuna, in common with that of more typical Lamelli-
branchs, consists of a central organ of propulsion, the heart, of arteries having a definite
lining of epithelial cells, of irregular ill-defined spaces or lacune, and of a well-
developed series of more or less well-defined and regularly disposed permanent channels
or sinuses, functioning in the main as venous trunks, but differing therefrom histo-
logically, as the walls of these sinuses are without an epithelial lining. The blood is
colourless.
It is characteristic of the Anomiide that the heart is not contained in a
pericardium, and this peculiarity is well seen in Placuna. Here the thick-walled
ventricle (V.) lies suspended freely in the mid-posterior region of the pallial cavity, just
above the posterior ventral angle of the visceral mass ; its relative position is dorsal to
HORNELL—ANATOMY OF PLACUNA 75
the rectum, and in aspect its apex is turned slightly towards the left side (V. Plate II.,
fio. 4).
lis attachment to the visceral mass is by a narrow strip of tissue extending
upwards from the closely approximated entrances of the auricles to the emergence
of the aorta (Ao.). The ventricle is, therefore, not traversed by the rectum, nor even
closely approximated thereto ; indeed no intimate relation exists between them.
In shape the ventricle is roughly of sub-globular form, with the apex pointing
posteriorly and slightly to the left Its greatest length in the largest of the preserved
adults examined was not more than five millimetres, the greatest breadth four mm. The
walls are muscular and extremely spongy, allowing thereby of great distension ; the
cavity is crossed by numerous muscular trabecula (Plate V., fig. 28).
Two tubular auricles, one from each side (Au.r. and Au.l., figs. 16 and 17), enter
the ventricle at the ventral end of its attachment to the visceral mass; the auriculo-
ventricular apertures (V.a.v.) are placed close to one another, but each is quite separate.
Each is guarded by a clearly-defined mitral valve, consisting of two semi-lunar
membranes effectually preventing reflux of blood to the auricles. A single aorta, the
anterior, is given off from the ventricle a little way dorsal to the auriculo-ventricular
apertures, its opening provided with a single flap-shaped valve of simple structure
(V.ao.).
The auricles are paired and tubular; they differ considerably in calibre—another
instance of the far-reaching asymmetry of this mollusc, the left one being nearly double
the diameter of that on the right. They approach the ventricle horizontally from the
anterior aspect, and appear as two tubular arms embracing the base of the visccral
mass. They lie on the right and left sides, just beneath the thin tissue of the mantle
and midway between the dorsal aspect of the adductor muscle and the ventral portion
of the liver. Anteriorly each is continuous with a large vessel carrying blood from the
anterior apex of the ctenidium of its own side; indeed the auricles appear as the
terminal dilated portions of these vessels, the common efferent branchial trunks
(C.br.ef:). In this lack of specialisation the form of the auricles in Placuna is
particularly noteworthy.
In common with the Pectinaceze and Ostracee, the auricles themselves independ-
ently intercommunicate by a short transverse channel (Aw.ch., fig. 16), but Placuna
is remarkable in that this connecting passage is particularly wide, and situated relatively
so far distant from the ventricular end of the auricles as to be scarcely recognisable as
an inter-auricular channel. This abnormal situation is obviously consequent upon the
peculiarly elongated form assumed by the auricles. In one abnormal adult individual
obtained from Tuticorin (8. India) only one auricle, the left, opened directly into the
ventricle (Plate IIL., fig. 18). The right was connected in no way with the ventricle ;
it was continuous posteriorly with the rectal sinus, and anteriorly with the right
efferent branchial trunk. The transverse auricular canal appeared very wide, so
76 OKHAMANDAL MARINE ZOOLOGY REPORT ~
through this all the blood brought by the right auricle passed into the left auricle, and
thence into the ventricle by this indirect route. Probably this abnormality indicates
a tendency towards the eventual suppression of the right auricle, and to a condition
wherein the ventricle will have but a single auricle (the left) opening into it. We
can now understand why Placuna has but one aorta (the anterior), whereas in
most other Lamellibranchs there are both an anterior and a posterior aortic trunk with
independent egress from the ventricle.
The single aorta (Ao., Plate IIL, fig. 15) is given off from the ventricle close to
the dorsal extremity of its attachment to the visceral mass. It divides almost
immediately into two large trunks, (a) an anterior, running dorsally close to the
posterior edge of the visceral mass, and (b) a posterior, having a course directed
anteriorly and ventrally.
The anterior aortic trunk, the aorta proper, is markedly asymmetric in its
position ; it runs superficially immediately beneath the left surface of the visceral mass
and can be readily traced, together with the initial course of its main branches, by
removal of the left mantle, when these vessels are seen mapped out clearly on the
surface. The first two main branches given off by the aorta after the emergence of the
great posterior trunk both run anteriorly and superficially within the visceral mass for
a short distance and then turn inwards to supply the stomach, digestive gland and
portions of the intestine and gonad (Art.visc. and Art.hep., fig. 15). More dorsal
still, a small artery, the posterior common pallial artery (Art.c.p.), leaves the aorta
and, first running dorsally, curves round the ventral extremity of the posterior cardinal
hinge tooth, and then, when midway towards the hinge, turns posteriorly and runs
along the margin of a thin portion of reproductive tissue to the free dorsal edges of the
mantle, where it divides into two long peripheral branches, the right posterior pallial
arteries (Art.pp. and pp.'), which run respectively along the posterior edge of each
mantle lobe.
Having given off the posterior common pallial artery, the aorta curves forwards
and a little dorsally, and after sending a small vessel to supply the posterior half of
the median dorsal hinge lobe at the level of the hinder cardinal hinge tooth and
midway between it and the corresponding extremity of the anterior cardinal tooth, the
aorta finally ends by bifurcation into a dorsally directed anterior common pallial artery
(Art.c.a.) and a ventrally running palpar artery (Art.pa.). The former, after giving
off a small artery to the anterior half of the median dorsal lobe, passes forwards to
round. the ventral extremity of the anterior cardinal tooth and then upwards and
forwards to where the mantle lobes join anteriorly. Here the common artery
bifurcates in similar manner to its fellow at the posterior end of the hinge, and so
gives rise to two branches, the anterior pallial arteries (Art.a.p. and Art.a.p.'), which
run marginally within the anterior edges of the respective pallial folds. In this way
are formed two circumferential blood-vessels, one in each mantle, which run along the
HORNELL—ANATOMY OF PLACUNA 77
two edges from a point dorsal and anterior where they receive blood from the anterior
common pallial artery, to a point posteriorly where they receive blood from the
posterior common pallial artery. In each case it follows that streams of arterial blood
must meet each other within these pallial arteries, since they are fed from each
extremity ; however, as these pallial vessels give off numerous branches to the pallial
and velar edges and are of minute calibre, and as their blood-feeders are both among the
more distal of the branches given off from the aorta, the blood-pressure at that ventral
point where the two streams meet must be so greatly reduced as to cause no opposition
of blood currents to occur.
The common palpar artery curves. forwards and somewhat ventrally towards the
dorsal aspect of the palps, where it bifurcates to furnish a branch to each palp.
It is worthy of note that a special supply of arterial blood is furnished to the
tissues in contact with the anterior and posterior thirds of the hinge line, by a
series of minute but very distinct arteries branching off successively at short
intervals from the terminal section of the anterior and the posterior common pallial
artery respectively.
As already mentioned, the posterior branch of the aorta—what may be called the
ventral artery (Ao.v.)—arises at a point very close to the ventricle. It runs in an
anterior direction for a short distance, then turns ventrally, dipping between the two
tubular auricles, to run along the anterior aspect of the adductor muscle between the
kidneys, its calibre decreasing as it goes. Opposite the anterior corner of the base of
the visceral mass it gives off a fairly stout branch (Art.add.), which enters the
substance of the adductor and splits at once into a number of dendritic twigs. From
this point, continuing its course along the surface of the muscle, there is next given off
a long branch on the right side to the sac of the crystalline style, which thence runs
back along the whole course of the sac, supplying branchlets thereto as it goes.
At the level of the great parieto-splanchnic ganglionic mass three short branches
(fig. 15, Art.add’.) are given off successively from the ventral artery, which enter the
adductor muscle and split up dendritically into numerous ramifying branches and twigs.
Other small vessels are also derived from the extremity of the ventral artery; two of
these pass posteriorly along the ventral surface of the muscle towards the rectum, and
it is from each of these that a branch is given off to the pallial sense-organ.
Venous Sinuses.—Blood distributed to different parts of the body by the arteries
passes eventually into small ill-defined lacunar spaces, and these run together
into larger spaces, the sinuses, of greater definiteness and permanence. In Placuna
placenta the course of the principal sinuses is more easily followed than in most
Lamellibranchs ; these vessels separate in the main into two series—the pallial and the
viscero-pedal. The blood collected by the former, as well as that from the rectal
sinus, passes directly to the auricles by way of the common efferent branchial
trunks, while that from all the viscero-pedal sinuses, excepting the rectal, enters the
78 OKHAMANDAL MARINE ZOOLOGY REPORT
branchial circulation and passes to the gills for purification before being returned
to the heart. .
Pallial Sinuses.—Fig. 19 on Plate III. depicts graphically the arrangement and
course of the principal pallial sinuses within the left mantle. The principal one is a
great curved vessel, the anterior ventral pallial sinus (Sn.padl.a.v.), embracing within
its concavity the adductor muscle. It runs almost midway between the adductor and
the pallial edge, but rather closer to the former. The main branches feeding it appear
all to arise on the distal side, so their function is the draining of the pallial tissues
between the main sinus and the pallial edge. The sinus itself drains into the left
common efferent branchial trunk almost at its origin—that is, close to the fleshy
accessory excretory organ—but, just before doing so, receives a very large,
well-branched sinus—the anterior dorsal pallial sinus.
A somewhat similarly disposed pair of sinuses (Sn.pall.p.v. and Sn.pall.p.d.)
drain the posterior region of the left pallial lobe, but the two members are smaller,
with fewer branches than the members of the anterior pair. They join just behind
the level of the lower margin of the heart and run forwards at this level as the
common posterior pallial sinus to empty into the left common efferent branchial trunk
at the same place as the anterior pallial sinal opening. In the right mantle the anterior
ventral pallial sinus is about as well developed as its counterpart on the left side;
the dorsal member of the pair is weakly developed, and there appear to be no
equivalents present of the posterior pallial pair. The suppression of these latter and
the degencration of the dorsal member of the anterior pair is correlated with the fact
that the upper part of the right mantle, instead of being free, as is that on the left, is
adherent to the surface of the visceral mass. As a consequence, the function of the
suppressed pallial sinus is usurped by the visceral sinuses of the right side, which, it
is noteworthy to remark, are extensively ramified and much more highly developed
than those on the left side of the visceral mass. In this connection it may be
remarked that, so far as the blood system is concerned, the left aspect is pre-eminently
the arterial, the right is distinctly the venous.
Another point of great interest connected with the pallial sinuses is the association
of black pigment with their trunks and main branches. The intensity of pigmentation
varies considerably ; sometimes the whole mantle is more or less deeply suffused
externally, the sinuses showing up as darker lines on a dusky ground, the pigment
being denser along their course; in other individuals pigment is restricted to the
trunk vessels and their branches. The significance of this will be treated of elsewhere.
Visceral Venous System.—The principal vessels of this group may be enumerated
as (a) the unpaired rectal sinus, (b) the paired main visceral sinuses, (c) the small
median sinus, and the paired renal sinuses.
The first of these, the rectal sinus (Sn.7., fig. 15), runs along that posterior
portion of the kidney which overlies the rectum, and as they are closely associated, it
HORNELL—ANATOMY OF PLACUNA 79
would appear that some elimination of waste products may here take place. This sinus
receives some portion of venous blood from adjacent portions of the right mantle. It
runs directly to the heart, uniting with the right auricle just under the right auriculo-
ventricular aperture in such manner that it appears as if it were a backward
prolongation of this auricle, just as the right common efferent branchial trunk appears
as a forward prolongation.
Within the main visceral mass the two principal sinuses consist of an asymmetric
pair, disposed vertically close behind the junction of the palps with the body. The
right (Sn.v.7.) is the larger and has many branches, which in turn frequently
sub-divide. These branches drain blood from the greater portion of the visceral mass,
including the whole of the median and right sections of the main mass; a branch from
the posterior visceral lobe also empties into the main or vertical sinal. trunk.
The left main visceral sinus (Sn.v.l.) lies parallel to the right one, and receives
branches from the anterior portion of the right side of the visceral mass and also a
strong branch from the foot.
A very little above the level of the lower margin of the palps the left visceral
sinus turns inwards and joins its fellow on the right, forming a short median sinus
(Sn.m.). This almost immediately divides into two large, well-defined trunks, the
renal sinuses, passing ventrally to the paired limbs of the kidney. Here the blood
stream bathes the renal tubules with consequent elimination of waste products. From
the ventral extremity of each limb of the kidney and close to the parieto-splanchnic
ganglion, a common afferent branchial trunk (Cbr.aff.) conveys this partially-purified
blood into the branchial mesentery of its own side. The course of this afferent vessel
curves at first outwards (anteriorly and slightly ventrally), always within the
mesentery, till it reaches rather less than half-way to the proximal margin or base of
the gills. Here it divides into a short anterior and a long posterior branch. From
both branches a multitude of fine vessels carry blood from the afferent trunk into a
most extensive and intricate vascular network (Br.ms.pl., figs. 4 and 15), occupying
the whole distal section of the mesentery and from which eventually pass the
tubules supplying the branchial filaments.
The remainder of the branchial circulation is practically the same as in Anomia
and is described in the pages treating of the structure of the branchie. It will suffice
to say here that, after oxidisation in the mesenteries and the gill filaments, the blood
from the gills is returned to the heart by two common efferent branchial vessels, each
of which, as already noted, runs directly between the anterior apex of each gill and the
auricle of the same side—appearing, indeed, as a forward prolongation of the auricle.
Course of the Circulution.— We are now in a position to outline the course of the
blood circulation through the body. In the first place, we see that the blood reaching
the ventricle through the two auricles consists in part only of fully-purified blood from
the gills and kidneys, a portion of more or less impure blood arriving in the auricles
80 OKHAMANDAL MARINE ZOOLOGY REPORT
direct from the mantle lobes! and hinder portion of the body by way of the rectal and
the anterior pallial sinuses.
From the ventricle this mixture of pure and impure blood is pumped into all
parts of the visceral mass, muscles, and mantle. Thence it passes into irregular lacunar
spaces, from which the sinuses collect it. That collected by the pallial and rectal
sinuses goes, as already described, directly back to the heart, while that gathcred into
the visceral sinal vessels is carried to the kidneys and the gills, whence, after
purification, it passes by the common efferent branchial trunks into the auricles.
Reviewing the circulatory system of Placuna as a whole, several most noticeable
features become apparent. The more striking are, (a) the primitive tubular character
of the auricles in contrast with the specialised and centralised condition seen in the
more highly-developed pearl oyster, where the ventricle and auricles form a closely
associated or single mass; (b) the marked asymmetry of the auricles and their
inter-communication by way of a particularly wide channnel relatively remote from
the ventricle; (c) the presence of a single aorta, the anterior, consequent upon the
suppression of the posterior, whereof the place is taken by a large branch given off by
the anterior aorta immediately after it leaves the ventricle; following on this
suppression of the posterior aorta, we see that both the anterior and the posterior pair
of pallial arteries arise from the dorsal branches of the anterior aorta—in the pearl
oyster the anterior and the posterior aorta supply respectively one pair of these pallial
vessels ; (d) lastly, the absence of a pericardium surrounding the heart is particularly
striking, a condition of affairs confined among Lamellibranchs solely to the Anomiidee ;
this results in the ventricle lying free and uncovered within the mantle cavity.
Comparing with Anomia, we note in that genus that there are the vestiges of a
coelomic space in certain tiny glands or funnels opening into the two kidneys, according
to Sassi. In Placuna these laterally-placed “funnels” appear to be paralleled by a
conspicuous fleshy glandular body (accessory excretory organ) on each side, opening
respectively into the right and left nephridia.
Tendency towards further modification in organisation suggested.—From the
greater development of the left auricle considered in conjunction with the exceptional
width of the inter-auricular channel, it seems to me that there exists in Placuna a
well-marked tendency towards the eventual modification of the right auricle in such
manner that, instead of carrying the blood it receives to the ventricle, it will cease at
last to be connected organically therewith and instead will pour its blood stream
wholly into the left auricle by way of the further widened inter-auricular channel.
This theoretical deduction of the probable results is depicted in fig. 18, which, however,
is not an imaginary diagram, but an outline sketch of a similar actual, though
* This blood is probably oxygenated to some extent even though it does not pass through the
gills, as the pallial membranes are so tenuous as to be capable of allowing some exchange of gases
between the water without and the blood which flows within. In this way the wide expanse of
free pallium in Placuna may be considered in the nature of an accessory branchial organ.
HORNELL—ANATOMY OF PLACUNA 81
abnormal, arrangement of vessels noted in an individual obtained in 1907 from a
muddy inlet near the town of Tuticorin in South India. Here we see the rectal sinus
opening directly into a vessel, which, without doubt, is morphologically the right
auricle, but in this case with no connection whatever with the ventricle, inter-
communicating instead by a wide channel, the inter-auricular passage, with the left
auricle, and connected anteriorly with the right common efferent branchial trunk,
wherefrom it receives blood in the usual manner of a right auricle. In this individual
the ventricle has but two openings, that from the left auricle and that from the aorta.
EXCRETORY SYSTEM.
The excretory system is considerably removed from the normal Lamellibranch
type, a result of the absence of a pericardium and of the marked asymmetry of the
animal generally. ,
It consists of two paired asymmetric nephridia, connected dorsally by an extremely
short and wide transverse channel, the inter-nephridial passage. Two distinct regions
are recognisable in each nephridium, an anterior section consisting of a laterally
flattened tubular region, with much folded walls lying anterior to the inter-nephridial
passage, and approximately of equal size in both nephridia, and of a caecal continuation
directed posteriorly, of great length in the case of the right nephridium, short, and
little more than rudimentary in that of the left (figs. 6,7, and 8).
The general form and course may be readily understood if we represent the organ
diagrammatically as an H-shaped tubular organ with the posterior part of the left leg
much shorter than its fellow on the right, thus—H. It lies curved in crescent. form
round the greater part of the adductor muscle, the anterior symmetric horns or
branches curving downwards over the anterior face of this muscle, while the posterior
horn on the right, representing the czecal prolongation of the right nephridium, lies
upon the upper surface and along the greater part of the rectum. The caecum of the
left nephridium appears as the abbreviated horn on the left.
The two anterior branches of the conjoined nephridia (Neph.r. and Neph.1.),
usually of a dark brown colour, as are also the other sections, run parallel with each
other along each edge of the antero-dorsal curvature of the adductor muscle, and
thence downwards along its anterior face, terminating about the level of the parieto-
splanchnic ganglionic mass (fig. 4). Dorsally the two tubes communicate widely with
their posterior cecal prolongations.
The right branch in the anterior or symmetric region of the kidney is rather
broader than the left, and is more deeply lobed ventrally ; viewed superficially it
has the appearance of being partly sunk in the tissues of the right mantle. It is not so
in reality. Its posterior face is intimately associated with the proximal portion of the
pyloric caecum to which it is bound by a thin sheet of connective tissue. From its
82 OKHAMANDAL MARINE ZOOLOGY REPORT
anterior face the first section of the right branchial mesentery is hung, and in like
manner the fore part of the left branchial mesentery is suspended from the face of the
left renal tube.
The extremely short internephridial passage lies transverse to the median plane,
bounded dorsally by the visceral mass, ventrally by the adductor muscle, and anteriorly
by that ventrally-directed lobe of the visceral mass which pushes its way downwards
and forwards between the auricles and apparently through the nephridia in its
accompaniment of the pyloric cecal sac. Hence in serial sections we see the inter-
nephridial passage (fig. 24, [.n.p.) as a wide transverse channel connecting the two
nephridia immediately behind an “island” of reproductive tissue having a cross
section of, the pyloric caecum in the centre, and one of the ventral trunk of the
aorta to the left side.
Posteriorly each nephridium is prolonged in a posterior ventral direction as a cecal
prolongation ; that on the left very short, that on the right relatively of great length.
The latter runs for some little distance on the right side of the rectum, and then twists
over so as to run in a truly median plane along the posterior face of the rectum almost
as far as the anus.
Along most of its course the right renal caecum is accompanied by the rectal sinus
so that the blood thus carried to the heart has some part of its waste matter removed at
this stage of its cycle.
Each nephridium has a single opening (Rn.o.) to the exterior ; it lies at the ventral
extremity of each renal tube, and opens into the mantle cavity at the end of a short
narrow duct situated close to the parieto-splanchnic ganglion. To ensure more
effectively the rapid removal of the renal excretion poured forth by these ducts, each
aperture opens into a long open channel or gutter running close to the edge of the
adductor. That on the right side is particularly well developed ; at first it is narrow and
deep, but as it proceeds posteriorly it gradually widens and loses depth until at last it
dies away towards the hinder ventral angle of the adductor, the excretion it conducts
away being then well under the control of the excurrent outflow from the gills.
Of the two sections, the anterior region is the most glandular: there the walls are
deeply folded and pouched on a somewhat complicated plan (figs. 29 and 30, Neph.r.).
The walls of the internephridial passage and of the posterior caecal region are also fairly
extensively folded and puckered to increase the secreting area (fig. 28, I.n.p.).
The cells lining the walls of all sections of the nephridia are uniform in appearance
and size (fig. 27). They consist usually of a single layer of large irregularly cubical
secreting cells, very clear and much vacuolated. The cell wall is very distinct, and the
nuclei, of large size, are situated towards the bases of the cells. In some places the
cells are somewhat crowded, and occasionally may be two and even three deep.
The gonad opens in tie roof of the internephridial passage by a single small duct
(fig. 6, G'o.a.), once more emphasizing the asymmetry of this mollusc.
HORNELL—ANATOMY OF PLACUNA 83
Two other small ducts also open into the nephridia, one on each side from
a compact reddish-brown fleshy gland situated on each of the common efferent
branchial trunks immediately between the ventral margin of the palps and the anterior
ventral corner of the visceral mass. These two glands (figs. 4, 6-8, Acc.ex.o.) are
sub-triangular in lateral view, and measure about three millimetres along each side.
They are made up of closely-packed tubules lined with large cells which leave but a
smal] lumen (fig. 29, Acc.ex.o.) ; compact though they arc, there is little doubt that we
have here a highly-specialised form of Keber’s organ, or so-called pericardial glands.
It has been noted that no pericardium appears to be present in Placuna. The
same statement was formerly made of Anomia, but although Pelseneer argued that
the vestige of a pericardium does persist in a much reduced and vestigial form as an
obscure connection between the hinder portions of the nephridia, which in Anomia lie
on either side of the rectum, Sassi (loc. cit.) controverts this, and denies the existence
of any vestige of a pericardium.
In Placuna I venture to suggest that the two fleshy glands which open right and
left into the most dorsal part of the right and left nephridia respectively represent the
reno-pericardial tubes of Lamellibranchs more normal in the structure of this organ,
for example, Margaritifera vulgaris, where each of these tubes is seen as a wide sleeve
proceeding from the pericardium on each side to insertion in the wall of each lateral
nephridial chamber. In this type the ventral surface of the pericardium is beset with
excretory glands—a Keber’s organ. In Placuna it would seem as if these glands
had shifted outwards to the distal extremities of the reno-pericardial ducts and
there massed compactly, a change accompanied, if not indeed produced, by the gradual
obliteration of the central or true pericardial chamber. If this hypothesis be correct,
then the dark compact glandular bodies, secn one on each lateral wall of the renal
organ, represent all that is left in Placuna of the pericardium and reno-pericardial
tubes.
NERVOUS SYSTEM.
The central nervous system of Placuna, although it consists of the same
components as in other Lamellibranchs, suffers extreme secondary modification due to
torsion, fusion, and suppression of parts consequent upon the asymmetry of the other
organs and their general concentration and excessive development upon the right
side of the body.
It is constituted of the usual three ganglionic centres, (a) the cerebral, consisting
of two separate paired ganglia widely separated and asymmetric (figs. 10 and 11,
Cer.g.); (b) an apparently single pedal ganglionic mass (Ped.g.) formed by the fusion
of originally paired pedal ganglia, which are still resolvable as such on minute
examination ; and (c) a single median parieto-splanchnic ganglion (Par.sp.g.), showing
little trace of ever having been paired except in the paired nature of the nerves it
gives off,
84 OKHAMANDAL MARINE ZOOLOGY REPORT
The connectives follow the normal arrangement and number; a pair of long and
stout cerebro-visceral connectives (C.v.con.) join the cerebral and parieto-splanchnic
ganglia, while a very short pair of similar cords (C.p.con.) link the cerebral and pedal
centres.
In the living condition the ganglia and the stouter portions of the principal nerves
are bright orange yellow in colour, and since the ganglia are situated superficially this
enables them to be found with comparative ease.
The cerebral ganglia.—If the labial palps be folded back from the middle line, the
right ganglion (fig. 23, Cer.g.r.) may readily be seen lying superficially as a large and
conspicuous pale orange-coloured mass close to the united bases of the right pair of
palps, at a point about midway between the mouth and the base of the foot. ‘he left
ganglion lies at about the same horizon, at the bases of the left palps (Cer.g.l.) ; it is
distinctly smaller than the right, and as it does not lie so close to the surface it is
somewhat difficult to locate. A long U-shaped nerve cord, the cerebral commissure
(figs. 10, 11 and 13, Cer.com.), passing dorsally over the anterior end of the cesophagus,
unites the right and left ganglia; in consequence of the considerable distance from the
cesophagus at which the latter are situated, this cord is unusually long.
Ventrally, each ganglion gives off two other connectives, one short and delicate,
the cerebro-pedal connective (C.p.con.), to the pedal ganglion, the other very long and
stout, the cerebro-visceral (C.v.con.), to the parieto-splanchnic ganglionic mass.
Each cerebro- visceral connective runs in a ventral direction along the base of the
palps of its own side to the anterior extremity of the gills, where it leaves the visceral
mass and passes, still pursuing a ventral course, to between the anterior surface of the
adductor and the posterior of one of the renal tubes. Its further course follows that
of the renal tube of its respective side along which it runs on the postero-lateral
aspect to junction with the dorsal margin of the parieto-splanchnic ganglion.
In addition to the supra-csophageal commissure and the connectives to the pedal
and paricto-splanchnic ganglia, each cerebral ganglion gives off anteriorly a common
anterior pallial nerve (N.a.p.), which passes into the mantle at its antero-dorsal corner.
Other small nerves also arise from the cerebral ganglia to innervate the pallial
palps and adjacent tissues.
Pedal Ganglion.—The two primitive components of this nerve centre are so
closely approximated that they cannot be clearly resolved except by microscopic
examination of serial sections. The dual nature is then readily made out and it is
seen that the lateral mass which represents the original right ganglion is much the
larger of the two; no trace of commissure persists. The ganglion is situated medianly,
on the dorsal side of the base of the foot. In addition to the cerebro-pedal
connectives given off at its upper and external corners, a stout pedal nerve arises from
this ganglion and passes directly into the foot, where it can be traced to the tip, giving
off small twigs along its course.
HORNELL—ANATOMY OF PLACUNA 85
The parieto-splanchnic ganglion is the largest of the ganglionic centres and
attains relatively enormous proportions. It is not distinguishable into separate parts
further than may be suggested by the two small anterior lobes where the cerebro-
visceral connectives enter. It rests in a slight depression on the anterior ventral
curvature of the adductor close to the ventral extremities of the paired region of the
nephridia.
In addition to the connectives to the cerebrals, two distributory trunks, the
branchial nerves (N.br.), leave it anteriorly, while two other large nerves, the right
and left posterior common pallial, emerge from its hinder border, and a second pair,
the adductor nerves, pass from the posterior aspect direct into the tissues of the
adductor muscle.
The two branchial nerves appear symmetric and of equal size. One leaves each
anterior lateral corner of the ganglion, passes forwards, and at once enters the
branchial mesentery ; then, abruptly and at an acute angle, it curves posteriorly, to
run the remainder of its course approximately parallel with the ctenidial base. At
first the branchial nerve runs at some distance from this axis, but gradually draws
nearer as it approaches the posterior extremity of the gills, where it terminates. Hach
nerve gives off numerous branches in its course.
The adductor nerves, as mentioned, arise right and left from the posterior surface
of the ganglion. Their sole function is to innervate the adductor muscle ; in saggital
serial sections through young individuals their dentritic branching is beautifully
shown (fig. 29).
The remaining nerve trunks, the great pair given off from the posterior border,
each breaks up immediately on leaving the ganglion into an inner or internal nerve
and several lateral ones. The first two of the latter, the pallial nerves (N.pail.),
radiate outwards to innervate portions of the mantle and, with the nerves from the
anterior common pallial trunks given off from the cerebral ganglia, form that complex
network of nerves within the mantle lobes known as the pallial plexus, while the third
passes posteriorly without turning outwards till, when close to the distal end of the
pyloric caecum, it bends ventrally, to pass direct to the elongated tumid pallial sense
organ wherein it bifurcates.
The inner nerves (N.v.v.) pass posteriorly within the sheath of the adductor
muscle in the direction of the anus. They appear to innervate the tissues and organs
of the ventral rectal region.
The only sense organs present are of an extremely low type, showing a minimum
of specialisation. Neither otocyst nor osphradia appear to be present. A pair of the
pallial or abdominal organs of Thiele are, however, present. With this exception, all
we have is the development of sensory epithelial cells singly and in small groups upon
the papillate processes of the mantle edge. In general they have the structure and
arrangement of those seen upon the pallial edge of the pearl oyster. oe
H 4
86 OKHAMANDAL MARINE ZOOLOGY REPORT
surface of the mantle and the palps is also sensitive, but not to greater degree than is
usual among other Lamellibranchs. -
Each of the pallial sense-organs (figs. 10, 11 and 13, S.o.) is an elongated tumid
body situated on the inner surface of each mantle close to the distal end of the pyloric
cecum. Innervation is by a strong branch of the posterior common pallial nerve,
which splits up into two principal branches immediately upon entering. The surface of
the swelling is covered with epithelium containing specialised sense-cclls. The size of
these bodies is very much greater than in Marguritifera vulgaris, implying a function
of considerable importance.
THE REPRODUCTIVE ORGANS.
Placuna placenta is dicecious and the sex of each individual remains the same
from season to season throughout life; no form of hermaphroditism occurs.
In each sex the gonad or reproductive organ appears to the naked eye as an
irregular mass of yellowish tissue largely enveloping the stomach, liver, and intestine,
and pushing out irregular tumid lobes into various parts of the right mantle. No
sign is given that the gonad is paired. Even in very young specimens there is
absolutely no evidence in favour of such view, whereas the presence of a single genital
opening and the great asymmetry of the organ point to the suppression of the left
member ‘of the original pair. The one remaining is purely and simply an irregular
ramified mass closely associated with the course of the alimentary canal. It is
distinguishable as a central mass and a definite number of large lobes; the first, as
before stated, envelopes and hides the greater portion of the stomach, liver and
visceral coil of the intestine, constituting the greater part of the outer tissue of the
main visceral mass. The lobulated masses which burrow in various directions into the
right mantle consist of two thin extensions into the dorsal or hinge lobes of the
mantle, one anterior and the other posterior to the central lobe bounded by the
cardinal teeth ; one long, narrow, greatly curved lobe following the entire course of the
pyloric cecum (fig. 13), first downwards along the anterior face of the adductor and
then turning posteriorly along its ventral aspect to a blind termination not far from
the posterior end of the gills; another tumid and somewhat irregular mass envelopes
the rectum, with it forming the rectal lobe of the visceral mass ; the last of the large
sections of the gonad lies immediately posterior to the visceral mass (Go.p.,
figs. 4 and 13).
The last two lobes in conjunction with the posterior face of the visceral mass
bound the triangular cardiac chamber, except on the lateral aspects; at the dorsal and
posterior angles these three masses are united and placed in communication with
each other by short and very narrow bridges of reproductive tissue; the intercom-
HORNELL—ANATOMY OF PLACUNA 87
munication of these large lobes of the gonad is a very noticeable feature in
Placuna.
Except the unimportant dorsal or hinge lobes which belong strictly to the main
mass of the gonad enveloping the stomach and liver and are median in position, all the
above-mentioned branch masses lie within the right mantle. The only portion that
penetrates the left mantle is a small branch from the pyloric cecal lobe which crosses
from the right side at the attachment of the ventral end of the kidneys to expand into
a disc-shaped mass covering and surrounding the proximal ends of the pallial muscles
of this region.
The gonad in the male appears usually to be rather smaller than in the female.
The sexes may be distinguished by the colour of the gonad; in the ripe female it is
normally of an orange yellow tint, in the male it is duller and has more of a soiled
yellow hue.
_ The gonad opens into the internephridial passage by a small aperture (Go.a.,
fig. 6) situated in the roof of the passage. The aperture is therefore anterior to the
ventricle, and midway between the auricles. From the position of the single genital
aperture being in the roof of the internephridial passage, the reproductive products,
when emitted into the renal organ, will pass readily in part to the right and in part to
the left, and so be conducted into the respective ventral limbs of the nephridium,
whence emission to the exterior will take place through the renal apertures situated on
either side of the parieto-splanchnic ganglion.
Microscopical examination shows that intermingled throughout the whole gonad
in both males and females is a very peculiar soft spongy tissue of obscure significance.
Its nature is absolutely distinct from that of the reproductive tissue proper; in
appearance it simulates a delicate and loose network of connective tissue. In young
specimens the proportion of this enigmatical tissue is very large and it would appear to
perform some distinct function other than that of a mere stromal framework—possibly
it functions as a food reserve (see p. 91 for further remarks on the significance of
this tissue).
Histologically each gonad is made up of a mixture of the spongy tissue above
mentioned with great numbers of ramifying tubules on which cluster, grape-like, dense
masses of saccate alveoli lined with germinal epithelium. The ultimate structure of
the alveoli is best seen in a female. Here they are distinguishable as wide ceca
containing ova in various stages of development, from a tiny cell arising by
proliferation from the germinal epithelium lining the cacum to ova free and fully
formed. ready to pass away.
Each ripe ovum when not deformed by reason of mutual pressure when the
tubules are becoming swollen with undischarged ova is of a laterally compressed
ovate outline (figs. 35 and 86), the narrow or stalked end having formed the place of
attachment to the alveolar wall. Because of this last fact, the narrow neck of this
88 OKHAMANDAL MARINE ZOOLOGY REPORT
stalk eventually functions as a micropyle. The vitelline membrane enclosing the
granular vitellus is slightly vacuolated; the nucleus is large and very granular and
often contains two distinct nucleoli.
The spermatozoa arise by a similar proliferation of the germinal epithelium in the
males; in maturing individuals the simple nature of cach of the alveoli is masked
by the presence of large quantities of unripe spermatozoa which obscure and practically
obliterate the lumen. The individual spermatozoa are very minute and of the typical
form seen in Lamellibranchs, each having a pear-shaped head, elcar and highly
refractile, with a long, delicate flagellum proceeding from the broader end.
The spawning season of Placuna appears to coincide with the onset of the north-
east monsoon both in Ceylon and the Gulf of Kutch, the two localities where I have
had opportunities to examine large numbers of individuals of various sizes. Thus in
January, 1906, I found oysters of 1°5 centimetres diameter about three months old in
Rann Bay on the Okhamandal coast, while the young seen in Tampalakam Bay,
Ceylon, in May, 1905, being 4 cms. in diameter, were approximately six to seven
months old—ages which give the spawning season as the month of October in the
preceding year.
On @ priori grounds this is what might be expected. The month of October
witnesses a great change in weather on the Indian coast, with a concurrent
variation in the specific gravity of the water on the Placuna banks. In Ceylon this
is specially emphatic. October is pre-eminently a rainy month in the Tampalakam
district ; the influx of fresh water into the bay which results lowers the specific gravity
and supplies the needed stimulus reyuired by the window-pane oysters to bring on
widespread emission of the genital products.
THE SIGNIFICANCE OF THE ASYMMETRY AND OTHER MAJOR
PECULIARITIES OF PLACUNA PLACENTA.
The most striking and outstanding features which characterise the organisation of
Placuna ave the marked asymmetry affecting almost every organ, and the archaic
characters retained by many of them.
Regarding asymmetry, F. J. H. Lacaze-Duthiers, working a half nai ago on
the anatomy of Anomia ephippium, belonging to a closely related genus, “ was struck
at the outset of the investigation with the importance aud preponderance which the
right mantle assumed over the left.” A similar remark would apply with equal force
to Placuna placenta.
In this species asymmetry affects practically the whole organisation. It is carried
so far in the case of the reproductive system that this may be said to lie almost
wholly within the right mantle.
The auricles are markedly asymmetric in calibre ; the sinuses of the two mantle
HORNELL—ANATOMY OF PLACUNA 89
lobes differ greatly in arrangement, whilst the posterior or rectal sinus is now unpaired ;
the posterior aorta has been suppressed; the hinder extension of the right kidney has
developed at the expense of its neighbour on the left; the palps are asymmetric and the
mouth and labia awry; the alimentary canal tends towards the right side, whilst the
crystalline style, after its emergence from the visceral mass, lies embedded for the rest
of its course within the right mantle lobe. The right member of both the retractor
and the levator pair of muscles of the foot has disappeared and the nerve ganglia, as
may be expected, share, though in modified degree, in the general asymmetry of the
animal.
The meaning of this asymmetry is explicable if we consider the peculiar mode of
life and habitat adopted by Placuna.
In Lamellibranchs possessing a byssus, by which they are enabled to athx to stones
and rocks, and in siphonate forms which burrow in sand or mud, the body is
maintained normally in a more or less vertical position. In Placuna, where both
byssus and siphons are absent, the animal lies prone on the convex left valve upon the
muddy bottom of those shallow waters of the Indies which it chooses as its habitat.
It thus lies with the body in a horizontal position, with its organs more or less
suspended from the flat right valve which is uppermost. In the same way its ally,
Anomia, assumes a more or less horizontal position in life, as in it the byssus, which
here protrudes in a calcified form from the right valve, anchors the animal permanently
on its right side to some solid object, rock, stone, or another shell.
Now, in those forms of Lamellibranchs where the axis of the body is regularly
maintained throughout life either approximately vertical in burrowing forms
(Cardium, Mya, Solen), or at right angles to the plane of attachment in the case of
fixed forms, asin Arca and Mytilus, the primitive bilateral symmetry is maintained,
whereas in Anomia and Placuna, which maintain a horizontal axis in their habitat,
asymmetry reaches a maximum. Intermediate forms of Lamellibranchs, with the axis
of the body maintained habitually in some position between these extremes, reveal an
asymmetry usually proportionate to the extent of the inclination of the axis of the
body from the vertical. Thus, in the pearl oyster (Margaritifera vulgaris), where the
inclination from the vertical is but slight, asymmetry is correspondingly small, and
may be said 1o be limited to the valves of the shell. In these latter forms the
conditions which produce asymmetry are mechanical, and are in the nature of stresses
comparable with those which account mechanically for the asymmetry of typical
gastropod structure.
But mechanical stresses will not account for the asymmetry of organs as seen in
Placuna, otherwise instead of the organs tending to gravitate to the right or upper
side of the body as the animal rests on the bottom, they would tend by gravitation to
embed themselves in the lower or left mantle. The cause is rather to be sought in the
obvious advantage of keeping the organs raised as far as possible above or beyond the
90 OKHAMANDAL MARINE ZOOLOGY REPORT
harmful influence of the mud whereon the shell rests. The reason for the animal
lying on its convex side is unmistakeably the same. As mud-laden water enters the
shell to pass to the gills, the heavier particles tend to settle and deposit, and it becomes
a manifest advantage to have the organs on the aspect above where this settling takes
place. The scallops (Pecten maximus especially) and the edible oyster (Ostrea) supply
analogies of the advantage to unattached animals, whose life axis is horizontal, to have
one of their valves convex upon which they may lic. Pectcn rests thus, while in the
case of the oyster (Ostrea), which in the natural condition, living attached to rocks, is
attached by its left or convex valve, those that have been detached for cultural
purposes are preferably laid down upon this convex valve, as this is found distinctly
beneficial.
Tn all Lamellibranchs, with the exception of the Anomiidez, the excretory system
opens on the one hand to the exterior and on the other into a definite portion of the
ccelom—the pericardium. In the Anomiidez, typified by the genera Anomia and
Placuna, the absence of a pericardium is characteristic, and renders them unique
amongst Lamellibranchs.
It was only in 1903 that Sassi (doc. cit.) was able to show that minute vestiges
of the ccelomic cavity do persist in Anomia in the form of tiny blind tubules
communicating with each kidney, but without relationship to the heart. Sassi at the
same time showed that the transverse tube, or internephridial passage connecting the
kidneys, is not of coelomic value, being lined with cells similar to the secretory cells
in other parts of the renal organ.
In Placuna there is, as we have seen, a wide duct connecting the right with the
left kidney. This is, undoubtedly, strictly homologous with the transverse renal
passage found by Sassi in Anomia; in both the passage lies anterior to, and at the
level of, the ventricle, and between the crystalline style sac and the rectum ; in both,
the cell structure of the wall is similar to that of the general renal surface. This last
fact compels us to look elsewhere in Placuna for the vestige of a coelomic cavity.
I have been able to find nothing similar to the two groups of blind ciliated funnels
(“ Wimpertrichtern”) described by Sassi as representing minute vestiges of the coelom,
but I am strongly inclined to the belief that the pair of small triangular glandular
organs, one of which is situated superficially on each side at the anterior ventral corner
of the visceral mass, and which open into the most dorsal section of cach kidney, are
comparable to them and probably homologous. As in Sassi’s funnels, in Anomia they
lie in front of the passage connecting the kidneys ; likewise they open directly into
these organs.
In Placuna these glandular bodies are much larger, more compact, and more
conspicuous than those in Anomita. They appear functionally to be of superior
importance, and exhibit a suggestive resemblance to the dark-hued pericardial glands
(Keber’s organ) so frequently met with in other Lamellibranchs, as, for example, the
HORNELL—ANATOMY OF PLACUNA 91
dark brownish glands upon the auricles of the pearl oyster. If my theory be correct
then we have in Placuna, in these accessory excretory glands, the homologues of Sassi’s
ciliated funnels and the sole vestiges of the ccelomic cavity.
Were we to suppose, as is not unreasonable, that originally Placuna had a fairly
normal pericardial ccelomic space, with a group of accessory (pericardial) glands on the
inner surface of the pericardial wall towards the reno-pericardial apertures, then we have
now a condition where the pericardial cavity has become obliterated with a concurrent
development of the pericardial glands on each side of the body around what was
originally the reno-pericardial aperture. The present extreme forward disposition of
these glands, and consequent remoteness from the ventricle, is of uo force against this
view for two reasons, namely—(a) the auricles, which it is difficult to differentiate
from the common efferent branchial trunks, reach as far forward as the glands in
question—indeed the base of each gland is connected with the upper wall of the efferent
branchial trunk, and (0) in several molluses, as in Margaritifera, each reno-pericardial
canal is so clongated forwards that its aperture is close to the anterior apex of the gills,
a position similar to that of the glands present in Placuna. The ‘aperture of each of
these accessory excretory glands may be considered as the morphological equivalent of
a reno-pericardial aperture of more normal types, and the glands themselves as the
sole remnant of the ccelomic cavity.
Yet another extreme peculiarity seen in Placuna is the presence of a large
quantity of delicate tissue intermingled with the tubules and ducts of the gonad. It
appears to be too abundant to be regarded as constituting a stromal framework, but so
far I am unable to determine definitely its significance. The one suggestion I have to
make is that it possibly constitutes a food reserve, to be drawn upon when the condition
of the water in which the individual lives is unfit for some reason to supply a
sufficiency of food. For example, I believe that with many molluscs there are periods
when, on account of excessive turbidity due to the suspension of great quantities of
mud particles, feeding becomes so difficult and unsatisfying that this function is
temporarily suspended, either wholly or in part. In the case of pearl oysters (MZ.
vulgaris) in aquaria I have noticed a cessation of feeding to occur whenever on
occasions the water supply (which passed to the aquaria without filtration) became
charged with an excessive amount of finc sediment. In such cases, although the
particles would be collected upon the gills and conveyed to the palps, these organs,
after carefully forming them into pellets, invariably rejected them as unfit, presumably,
for food purposes. Placuna lives under conditions where every flood carries quantities
of fine sediment into its favoured backwaters, and where, too, tidal influences and
wind-lop are often sutliciently strong to disturb the light sediment resting on the
bottom of the shallows. Under such circumstances it would appear to be of distinct
advantage to an animal to have a food reserve which would permit of temporary
cessation from feeding when the condition of the medium in which it lives
92 OKHAMANDAL MARINE ZOOLOGY REPORT
is unfavourable for obtaining food without an undue admixture of unsuitable
particles.
Backwaters, more or less brackish, are notable for a profusion of diatomacez ;
these organisms form the bulk of the food of Placuna, and to this fact we may
correlate the extraordinary development of the crystalline style in this molluse. Much
enveloping gelatinous matter is needed to surround the sharp ends of the silicious
frustrules and so prevent injury to the delicate walls of the intestine, and such supply is
afforded by the continual wearing down of the end of the style where it projects into
the stomach.
In its evolution Placuna, while retaining many archaic characters, as in the
primitive disposition of the heart and the simple structure of the branchial filaments,
has shown great plasticity in other directions, with the result that it is now one of the
most interesting of Lamellibranchs in its peculiarities of general. asymmetry and the
extreme specialisation of certain organs; its ensemble is now such as adapts it most
perfectly to the habitat it has chosen—an adaptation to environment second only to
that most wonderful of mud-dwellers, Lingula, where the same end has been attained
by an absolutely different path. In the one case life in an environment of the softest
mud has been rendered possible by the adoption of the same principle as is embodied
in the use of snow-shoes; here the animal rests upon the mud. In the other instance
a muscular stalk of great length has been developed to enable the animal to project the
edge of its valves above the mud, and yet have an anchorage to some shell or stone
far down in the deeper and stiffer layers of the mud. At Balapur Bay, in Beyt Island,
] have seen these animals living together in great abundance. Such mud-flats may,
therefore, be characterised as distinguished by a Lingula-Placuna formation.
EXPLANATION
OF PLATES.
INDEX TO REFERENCE LETTERS.
A.ch, afferent blood channel of gill filament.
A.l.e, antero-lateral cilia of gill filament.
Acc¢.ex.0, accessory excretory organ.
Add, adductor muscle.
Add’, anterior region of adductor muscle.
Add”, posterior ,, vs +
An,f, anal funnel.
Ao, aorta.
Ao.v, ventral trunk of aorta.
u.ch, interauricular channel.
Au./, left auricle.
Aur, right auricle.
Art.add, dorsal arteries of adductor muscle.
Art.add’, ventral arteries of __,, ”
Art.a.p, right anterior pallial artery.
Art.a.p’, left 3 5 +5
Art.c.a, anterior common pallial artery.
Art.c.p, posterior ,, . fr
Art.hep, hepatic artery.
Art.pa, palpar artery.
Art.p.p, right posterior pallial artery.
Art.p.p’, left A 3 ii
Art.vise, visceral artery.
Br, branchia.
Br.acec, accessory fold of the reflected outer
branchial lamella.
Br.eff, efferent branchial vessel.
Br.l, left branchia.
Br.ms, branchial mesentery.
Brms.pl, plexus of blood capillaries in branchial
mesentery.
Bry, right branchia.
Br.ret, branchial muscle band.
C.br.aff, common afferent branchial vessel.
C.br.aff’, left common afferent branchial vessel.
wt *
C.br.agt ’ right ” ” ” ” »
98
C.br.ef, common efferent branchial vessel.
C.p.con, cerebro-pedal connective.
C.st, crystalline style.
C.st.c, 5 $5
C’.t, cardinal teeth.
C.v.con, cerebro-visceral connective.
cecum.
Cer.com, cerebral commissure.
Cer.g, cerebral ganglion.
Cer.g.l, left cerebral ganglion.
Cerng.r, right ,, y
D.gl, digestive gland.
Digl.d, ,, » ducts.
L.ch, efferent blood channel of gill filament.
E.ep, epithelium of outer pallial surface.
L, foot.
Fc, frontal cilia on outer face of a gill filament.
Fl.trt, fleche tricuspide.
Go, gonad.
Go.a, external aperture of gonad.
Go.p, posterial genital lobe.
I.n.p, internephridial passage.
Zep, epithelium of inner pallial surface.
Int, intestine.
Int. 1, first or ascending limb of intestine.
Int. 2, second or descending limb of intestine.
L.c, lateral cilia of a gill filament.
L£.n.c, left nephridial cecum.
Lev, pedal levator muscle.
Lev’, insertion surface of levator muscle.
JAfcns.a, insertion surfaces of the anterior pallial
muscles.
Jl.ins.p, the principal insertion of the posterior
pallial muscles.
Ag.p, pallial margin.
Afg.v, velar margin.
iV, nerve.
94 OKHAMANDAL MARINE ZOOLOGY REPORT
N.add, adductor nerve.
N.a.p, anterior pallial nerve trunk.
NV.br, branchial nerve.
N.pall, pallial nerves.
NV.s.0, nerve to pallial sense organ.
V.v, visceral nerves.
NV.v.v, ventral visceral nerves.
Neph.t, left nephridium.
Neph.r, right nephridium.
O, mouth.
Oe, esophagus. ‘
Pa, palps.
Pall, pallium or mantle.
Pail.l, left pallial lobe.
Pall.r, right
Par.sp.g, parieto-splanchnic ganglion.
Ped.g, pedal ganglion.
2 ”
Periost, periostracum.
R, rectum.
F.n.c, right nephridial cecum.
Ret, retractor muscle of foot.
En.o, renal orifice.
S.0, pallial sense organ.
Sep, transverse septum of gill filament.
Sk.b, skeletal band within a gill filament.
Sn, blood sinus.
Sn.m, median sinus.
Sn.p, pedal sinus.
Sn.p.o, opening of pallial sinuses into common
efferent branchial vessels.
Sn.p.v, branches of posterior visceral sinus.
Sn.pall.a.v, anterior ventral pallial sinus.
Snr, rectal sinus.
Sn.rn, renal sinus.
Sn.v.l, left visceral sinus.
Snr, right ,, 3
St, stomach.
V, ventricle.
V.ao, aortic valve.
V.a.-v, auriculo-ventricular valves.
V.gt, gutter along ventral surface of rectal
genital lobe.
V.v.l, ventral visceral lobe.
Vel, velum or velar margin.
X, left branchiae cut across, posterior half re-
moved.
X’, mantle cut away along this line.
PLATE I.
Fig. 1. Young window-pane oysters (P. placenta) of three ages, all seen from left side. The youngest
is probably not more than six weeks old, the three oldest three to four months. Note that
all the latter show well-marked “ears”; as many as three anterior ones are shown by the
one on the left, bottom row. x #.
3 2. Two adult individuals, two to two and a half years old, seen from the right side, showing
extensive injury caused by fish-bites, recent as well as of old standing. All injuries in
process of reparation. Fig. B shows the remains of a posterior “ear” of considerable size ;
Fig. A shows-a well-marked straight hinge line. x 3.
PLATE II.
Fig. 1. Inner aspect of the hinge region of the right valve of Placsuna placenta ; note the two long
cardinal teeth of which the posterior is the longer, and the long row of short binge teeth
along the lower edge of the ligament (2).
Fig 2 and 3. Similar views from within of the hinge region of two left valves, showing the high
variability of the hinge dentition. In these views the two long divergent black bands
(L.c.t), represent the ligaments of the cardinal teeth belonging to the right valve. J, hinge
ligament with dentated margin corresponding with the row of hinge teeth on the opposing
valve. a.e and p.e, the anterior and posterior “ears” respectively of the shell.
Fig. 4. General anatomy of Placwna as actually displayed in a dissection ; the animal is viewed from
the left side, the left mantle lobe and the distal half of the left ctenidium being removed
along the lines marked X’ and X. Actual size of a two years old individual.
For explanation of the reference letters, see list above.
Fig.
10.
11.
13.
14.
15.
16.
17.
18.
19.
HORNELL-—. ANATOMY OF PLACUNA 95
Variations in the form of anal funnel in four individuals. x 5.
Diagrammatic representation of the two nephridia in plan, showing the unequal development
of the posterior ceca (2.n.c and L.n.c), the internephridial passage into which the genital
duct opens (Go.a), and the relation of the ventral visceral lobe (V.v./) which appears to
pierce the nephridial sac. Acc.ex.o, accessory excretory organ; An.o, external renal
apertures ; C.st, crystalline style; Ao.v, ventral branch of aorta.
Lateral view of the right nephridium.
Lateral view of the left nephridium.
Imp, marks the situation of the internephridial passage.
Insertion surface of the adductor muscle seen~-from left side. Add’, anterior region ; Add’,
posterior region.
Plan of the nervous system, showing the ganglionic centres, connectives, and principal nerve
trunks. For lettering consult the list on p. 93.
Nervous system dissected out and seen from the left side. (S.0, pallial sense organ; Add,
adductor muscle: O, mouth; Oc, esophagus. Other lettering as in Fig. 10.
Diagrammatic transverse section across the two ctenidia to show the relative arrangement of
lamelle and vessels. Br.ms, branchial mesentery; Br.aff. and Br. eff, afferent and efferent
branchial vessels respectively; #r. ace, accessory fold of the reflected outer lamella
(R.br.1); D.br.l, inner and outer direct branchial lamelle; Ctr and Ctl, right and left
ctenidia ; Cty, junction between inner reflected lamelle of right and left ctenidia.
PLATE III.
Dissection of Placuna placenta from the left side to show the course and situation of the
digestive system, position of heart, and other details. The left mantle, the whole of the
branchiz, the left nephridium, the left palp and the superficial portion (left side) of the
visceral mass have been removed. The foot is seen in moderate extension. 8.0, right
pallial sense organ; Sn.pall.a.v, anterior ventral pallial sinus of right mantle; C.st,
crystalline style. Natural size of a two years old individual.
Dissection of the alimentary canal, natural size.
Outline sketch of a dissection of a two years old individual to show the course of the blood
vessels. The vessels of the arterial system are shown by means of double lines, while the
venous sinuses are shown in heavy black. The outline of the branchie is shown by means
of a dotted line. Natural size. For explanation of lettering see list on p. 93.
Diagram of heart seen from left side.
55 rey » 9» Vight side.
Diagram of an abnormal heart found in an individual from Tuticorin ; in this case the right
auricle does not communicate with the ventricle. Compare with Fig. 17 where the normal
arrangement is depicted.
Lettering for these figures :—
V, ventricle; Aw./, left auricle; du.r, right auricle; Au.ch, inter-auricular channel ; Ao,
aorta ; Ao.v, ventral branch of same ; Sz.r, renal sinus.
Left pallial lobe viewed from without, to show the elaborate fan-like branching of the pallial
muscles and their insertion centres (M/.ins.q and M.ins.p), anterior and posterior to the
adductor muscle (Add), also the course of the pallial blood sinuses (Sn.pall). These
branched vessels are distinguished by means of double lines. Lev’, insertion surface of
pedal levator muscle,
96
eee
23.
25.
27.
28.
29.
OKHAMANDAL MARINE ZOOLOGY REPORT
Part of the digestive gland and the superior branches of the aorta are indicated faintly
through the thin non-muscular portion of the pallium adherent to the surface of the
visceral mass. Nat. size.
Semi-diagrammatic view of one of the minute spherical cestode larve found abundant in
P. placenta, seen in optical section, showing how asexual multiplication occurs by the
production of endogens. Only a single endogen (nd) is here seen, but individuals
frequently contain several ; C’.c, calcareous corpuscles,
Advanced larva of Distomun placune, n.sp., a trematode frequently found encysted in this
stage in Placune from the Gulf of Kutch.
PLATE IV.
Vertical transverse section across the body of a three months old individual (preserved in
formalin) about midway along the longitudinal axis. The section passes through the
anterior section of the stomach and along the axis of the internephridial passage. It passes
posterior to the paricto-splanchnic ganglion, and shows the relative position of the auricles
(Aur and Aw./) to the nephridia (Weph.r and Neph.l), the manner in which the intestine
(Int) and the pyloric or crystalline style czecum (C.st.c) leave the stomach and the relation
of the distal region of the latter to the right mantle. x16.
Slightly oblique horizontal section of a similar individual at the level of the cerebral ganglia
(Cer.g.l and Cer.g.r). Shows sections across stomach (Sé); last part of ascending region
of intestine (Int. /) and initial part of descending intestine showing typhlosole (Jné. 2);
labia (Zab) and upper edge of root of foot (7). x 20.
Horizontal section at the level of left auricle (Aw.2), through ventricle (J”.), showing auriculo-
ventricular valves (J’.a.v), right nephridial cecum (2.7.c), crystalline style (C.st), pedal
retractor muscle (Ret); also the direct efferent blood channel from the left branchize
to the heart by way of the common efferent branchial vessel (C.br.ef") and left auricle
(Au). x16.
Transverse section through crystalline style sac (pyloric cecum) showing characteristic
uniformity in the length of the lining cilia (C.st.ci?) and the concentric ringing which the
style shows in section. x 90.
Transverse section of second or descending section of intestine ; showing form of typhlosole (ty).
x 100.
Section from typical glandular region of nephridium to show renal cells, x 320,
PLATE V.
Vertical longitudinal section, a little to the left of the median line, through a three months old
Placuna, Shows the emergence of the pyloric cecum (sac of crystalline style, C.st.c), also
pedal ganglion (Perd.g) below and close to the left cerebral ganglion (Cer.g.l). The section
cuts the internephridial passage transversely (J.2.p) and shows the highly muscular
character of the ventricle (V). x 12.
Section of another individual cut in the same plane but well to right of the median line.
Shows the entrance into the stomach of some of the principal ducts of the digestive gland
(D.gi.d), the emergence of the intestine from the stomach, the continuity of the right
nephridium (Neph.r) with the right nephridial cecum (f.n.c), the situation of the
accessory excretory organ (Acc.ev.0) at the most dorsal portion of the nephridium, and the
crystalline style sac dividing the right nephridium into two ventral lobes (Nephr and
Fig. 30
» 3.
» 32
» 33.
HORNELL—ANATOMY OF PLACUNA 97
Neph.r’). The succeeding serial section on the outer side misses the heart (VY) which here
is just touched superficially. x 12.
A section belonging to the same series as that of Fig. 29, but nearer the middle line. It
shows more clearly the structure of the right nephridium and its posterior cecum, and their
relation towards the crystalline style sac and the rectum (#). As the course of the former
is slightly sinuous it appears as two discontinuous portions in this section (C.st.s
and C.sts’). x 12.
Transverse section of the left nephridium (Weph./) at the insertion of the retractor muscle
(Ret) to show the much folded nature of the wall and the manner in which the left gill
(Br) is suspended by a mesentery from its outer margin. x 20.
Note.—The individual sectioned was not over four months old; in adults the foldings of the
nephridial wall are much more complicated and more numerous.
Section of the mantle lobe showing the marginal and velar processes and the origin of the
periostracum (Periost) within a deep narrow groove. x 80.
Face view of three branchial filaments to show the method of interlocking by means of ciliated
discs close to the free or ventral edges of the gills. x 120.
» 34, A typical gill filament in transverse section to show the histological structure and the arrange-
ment of cilia elsewhere than at the level of the ciliated discs. x 600.
Figs. 35 and 36. Two forms of ova as scen within the duct of the gonad. x 800.
MARINE ZOOLOGY OF OKHAMANDAL PLACUNA, PLATE |
Fie. 1.—Young Plucuna plarenta of three ages. x &.
[Photo by Viridha Kala Mandir, Baroda.
B
A
Colts
Fis. 2.—Two adult individuals, showing injuries inflicted by fishes. x
EXTERNAL APPEARANCE OF PLACUNA
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DESCRIPTION
OF A
NEW SPECIES OF PINNOTERES FROM
PLACUNA PLACENTA,
WITH A NOTE ON THE GENUS,
BY
JAMES HORNELL, F.LS.,
AND
T. SOUTHWELL, A.R.C.Sc., F.L.S.
[With One Plate.]
THE material upon which the following description is based was obtained during a
biological survey of the coast of Okhamandal in Kattiawar. The bays on the north-
east seaboard of this district have a bottom composed of extremely soft mud,
constituting an agreeable habitat for the window-pane oyster (Placuna placenta),
which exists there in extensive beds. During the dissection of numerous individuals
of this mollusc, large pea-crabs were found in nearly all cases. The large individual
size, greatly flattened appearance, and preponderance in number of the males at
once arrested attention as being conspicuously different from any species previously
met with by the observer. Later research confirmed the original impression that this
form of Pinnoteres constitutes a new species; on account of the particular habitat
wherein it is found the specific name placune has been considered appropriate.
The detailed description of the two sexes is as follows :—
Pinnoteres placune, n. sp.
FremMaLE.—Body soft and membraneous; carapace broader than long, circular in
outline, smooth and greatly flattened dorso-ventrally ; lateral margins entire; front
broad, sharply truncated, and straight. yes, eye-stalks, and the whole of the orbit
99 I
100 OKHAMANDAL MARINE ZOOLOGY REPORT
hidden in a dorsal view. Eyes small. Orbits circular, eye-peduncles short. Antenne
minute and placed within the anterior hiatus of the orbit.
Chelipedes smooth, the movable fingers being slightly hairy, and as long as
the palm.
Ambulatory legs slender and increasing in size posteriorly, except the fourth pair,
which are smaller than the first pair.
Dactyli of the third and fourth pairs one and a half times as long as those of the
first and second.
Dactyli of the last pair, hairy at the tips.
Abdomen seven-jointed, broadening considerably posteriorly.
Length of carapace 9 mm., breadth 11 mm.
Numerous females bearing eggs. Colour in formalin, dirty brownish red.
Matr.—Carapace smooth. Front broadly triangular, short, and _ raised.
Posterior, broad and sharply truncate. The oblique cervical grooves well marked and
terminating just external to the orbits. Eyes small and visible in a dorsal view.
Eye-peduncles very short. Antennules extremely minute. Antenne long with
peduncles backwardly projecting.
Chelipedes similar, short, and equal in length to the breadth of the carapace.
Merus slightly longer than broad, with a rounded entire crest on its distal external
face. Carpus slightly longer than broad, and curiously curved. Propodite longer than
carpus, dactylopodite almost as broad as long and somewhat flattened. Fingers curved
with a hiatus between them when closed, and hairy on their opposing surfaces,
Succeeding legs slender. First pair approximately equal in length to the chelipedes,
second pair longer than the first pair by slightly more than a dactylus, third pair
longer than second pair by a dactylus.
Abdomen narrow, permanently flexed under the body, and narrowing posteriorly.
First pair of abdominal appendages modified into long, cylindrical, rod-like bodies
which project: from beneath the abdomen.
Length of carapace 7°5 mm., breadth 9°5 to 10 mm.
Apart from sexual characteristics, the male differs markedly from the female
in (1) its much smaller size and (2) the form of the rostrum.
Pinnoteres placune is characterised by being extremely flattened dorso-ventrally,
by having the front of the carapace straight and broad in the female, and by the
somewhat squarish outline of the carapace.
Habitat.—Commensal within the mantle cavity of Placuna placenta, Balapur
and Rann Bays in the Gulf of Kutch, India; abundant.
Rare in the same species of Lamellibranch in Tampalakam Bay, near Trincomalee,
Ceylon, one to three fathoms.
Out of twenty adult Placune examined alive and hailing from Balapur Bay, Beyt
Island, in the Gulf of Kutch, one shell only was without any pea-crab commensal.
HORNELL AND SOUTHWELL—PINNOTERES PLACUN At 101
Of the rest,
10 individuals contained 1 female each;
ye) - Fe 1 female and 2 males each ;
9 5 i 1 female and 1 male each;
1 ms - 12 males ;
1 5 v 11 males;
1 5 ss 3 males;
2 A © 2 males each.
Besides these particular individuals, a large number of others of the same age were
examined without note being taken of the exact numbers of pea-crabs respectively
contained ; scarcely any were found without one or more of these guests free within
the mantle cavity. The majority were located in the neighbourhood of the anus.
Immature shells, as is natural, less frequently revealed the presence of commensal
pea-crabs ; when they did occur the crabs were more or less immature. It would seem
that the crabs grow towards maturity concurrently with their hosts.
Placunze from Ceylon rarely contain this commensal. One large female was, how-
ever, taken by one of us some years ago from a large Placuna fished at Tampalakam-
Bay, proving the geographical range to extend from the Gulf of Kutch to Ceylon.
A large number of Placune obtained from Tuticorin in South India yielded no
pea-crabs. It would be interesting to learn the reason why these crabs are so
abundant in one locality, so rare in the others. Environment appears generally to be
identical in all three localities.
Borrodaile, in his report on Marine Crustacea in ‘The Fauna and Geography of
the Maldives and Laccadives,” vol. i, p. 428, refers to the Pinnoteride as being
“small symbiotic crabs with very small eyes and orbits. Body usually more or less
rounded ; carpopodite of the third maxilliped does not articulate at or near the inner
angle of the meropodite. Body usually square or squarish. Male openings sternal.”
Laurie, describing a new species of Pinnoteres from the Gulf of Mannar (‘ Ceylon
Pearl Oyster Reports,” vol. v.), characterises the carapace of Pinnoteres margaritifere
as ‘‘circular, calcified, smooth and polished. It is flattened a good deal, though a
little convex.”
A specimen of Pinnoteres abyssicola, Alcock and Henderson, was taken from a
living individual of a large species of lamellibranch (Lima indica, E. A. Smith)
dredged off the coast of Travancore at a depth of 439 fathoms. This specimen,
which was a female with eggs, had ‘“ the carapace as long as broad, circular and smooth.
The whole of the eyes and eye-stalks, and almost the whole of the orbits, visible in a
dorsal view.”
A specimen of Pinnoteres villasulus, Guerin Minivelle, found within the pearl
oyster in Torres Straits and presented to the Challenger staff (Challenger Reports,
vol. xvii.) had the front ‘“ deflexed and trilobate.”
I 2
102 OKHAMANDAL MARINE ZOOLOGY REPORT .
In the case of Pinnoteres ostreum, recorded from the East Coast of America, the
female only is commensal with Ostrea virginica, whilst the male is free-swimming.
It is interesting to note from the preceding that only in the case of Pinnoteres
margaritifere is the carapace referred to as being much flattened.
Specimens of Pinnoteres placune, n. sp., are particularly characterised by being
so compressed dorso-ventrally as to be quite flat. This, of course, is exactly what
one would expect to find in a species commensal with a bivalve in which the valves of
the shell are so closely approximated as in the case of Placuna placenta. In this
connection it is interesting to note that P. placune and P. globosus form two extremes
in the form assumed by the body. As we have seen, P. placune is remarkably
flattened, whereas P. globosus, as the specific name implies, is globular in appearance.
These facts serve to indicate the plasticity of the members of the genus and the
readiness with which they adapt themselves to their surroundings.
It will be noticed that P. poswm is more or less cosmopolitan, having been
recorded from England and from New Zealand; it would seem that other species of
Pinnoteres are local variations of P. pisuwm. The specific and restricted distribution
of certain of the species, such as P. margaritifere and P. placune, appears to confirm
‘this idea.
The following is a list of the species of Pinnoteres recorded up to date, as far as we
have been able to ascertain, with their respective hosts and the localities where they
occur :—
SPECIES.
Host.
DisTRIBUTION.
P. piswm (Tennant)
P. margaritifere, Laurie
P. placune, Hornell and South-
well
. rouxt, M. Edwards
. villosus, Guir.
. parvulus, Stimpson
globosus, Hemb. Jaques
(= obesus, Dana)
velerum, Bosc.
. abyssicola, Alcock and Hen-
derson
. villasulus, Guerin Minivelle
edwardst, De Man
pectent
ostreum
. purpureus, Alcock
. mactricola, Alcock
Se St Sh Sth
Modiola, sp.
Ceylon Pearl Oyster (Jf. vulgaris)
Placuna placenta
q
q
Pinna, sp.
Meroe quadrata and Cythrea, sp.
Lima indica
Pearl Oyster
Ostrea, sp.
Pecten, sp.
Ostrea virginica (male free-swim-
ming, female only in oyster)
Ostrea, sp.
Mactra violacea
Mediterranean; New Zealand
Ceylon Pearl Banks
Gulf of Kutch
Indian Seas
q
New Zealand
China Seas
Off Travancore, 439 fms.
Torres Straits
King Island Bay
E. coast of North America
Do.
Andaman Islands
Hoogly River, India
HORNELL AND SOUTHWELL—PINNOTERES PLACUNZ:
SO) OO ey, (SP tay Sones
=
S
EXPLANATION OF PLATE.
Adult male Pinnoteres placune, u. sp. Dorsal view. x 54.
Ventral view of same. x 5}.
Fourth walking leg of a male, right side. x 9.
Dactylus of same, more highly enlarged.
Dorsal view of an adult female carrying ova. x 8.
Ventral view of same. x 7.
Third walking leg from right side of a female. x 9.
Dactylus of third walking leg of a female. x 17.
Fourth walking leg from right side of a female. x 9.
Dactylus of same. X 17.
103
MARINE ZOOLOGY oF OKHAMANDAL. PINNOTERES, PLATE
G.Henry del PINNOTERES PLACUNA,n sp. Edwir Wilson, Cambridge
REPORT
ON THE
ANOMURA
COLLECTED BY MR. JAMES HORNELL
AT
OKHAMANDAL IN KATTIAWAR IN 1905-6,
BY
T. SOUTHWELL, A.R.C.Sc. (London), F.1.S.,
Naturalist to the Ceylon Company of Pearl Fishers, Limited.
[With One Plate. ]
THE present collection of Anomura, though but a small one, is exceedingly
interesting for two reasons. First, as showing the considerable degree of variation
present in certain species of the family Galatheide, and secondly, the large size
of many individuals conveys to us some idea under what luxuriant conditions
they must have lived.
In all there are thirteen species, representing seven genera, and two of these
species are new, viz., Porcellana gaekwari and Polyonyx henderson.
The following is a list of species in the collection :—
Diogenes investigatoris, Alcock.
Clibanarius infraspinatus, Hilgendorf.
Clibanarius humulis, Dana.
Porcellana serratifrons, Stimpson.
Porcellana gaekwari, n. sp.
Porcellana tuberculosa; Milne-Edwards.
1 The opportunity afforded by this report has been taken advantage of to include reference to
several species from the Ceylon Pearl Banks, not previously described from that district.—T.8.
105
106 OKHAMANDAL MARINE ZOOLOGY REPORT
Polyonyx obesulus (White).
Polyonyx hendersont, n. sp.
Petrolisthes armatus (Gibbes).
Petrolisthes bosct (Andouin).
Petrolisthes, sp.
Galathea elegans, White.
Munda spinulifera, Miers.
All these species are shallow-water forms, and in most cases were taken in
under four fathoms.
With the exception of Porcellana tuberculosa, and the two new species,
all the forms herein described have previously been recorded from the Indian
Ocean. Both the new species included in this paper, viz., Polyonyx hendersoni
and Porcellana gaekwari were collected by me from the Ceylon Pearl Banks.
A noticeable feature of the collection from the Gulf of Kutch is the preponderance
of Galatheidee over the Paguride, both in point of species and numbers. This
fact is to be correlated with the peculiar nature of the fauna on the ground
where the collection was made. The commensal habits of many genera included
in this family are well known. Generally, Galatheids and Munidids are to be found
crawling over the surface of dead coral, or under rocks, or upon living coral, but
the more brightly coloured representatives of the former genera—such as Galathea
elegans and G'alathea defleaifrons—are more commonly to be found commensal with
similarly coloured species of Comatulids.
On the other hand, the members of the genera Polyonyx find a home in the
large exhalant cavities of many species of sponge, and they are but rarely found
elsewhere. The species of Porcellana proper are likewise more or less commensal.
Their commonest habitat is amongst the short stumpy branches of different species
of Spongodes, many having pink or dark purple tips, and the colour markings of
the Porcellanids commensal thereon agree with those of the partner so well that
they are often difficult to see.
The Kutch collection was made on ground rich beyond description in corals,
sponges, crinoids, and such alcyonarians as Spongodes, and it is therefore natural
to find a predominance of such forms as usually occur in such a habitat.
The classification of the Galatheide adopted in this paper is the one adopted
in the Report on the Challenger Anomura, and the definitions of the genera
here given are also those therein given by Henderson. In the group Paguridea,
however, the classification adopted and the characters given are those given by
Alcock in his Indian Decapod Crustacea. In some instances I have had difficulty
in satisfactorily referring some of the Kutch genera to their proper place. Especially
was this the case in the family Porcellanide, and it would appear that, with our
extended knowledge of this group, a more suitable and precise method of classification
SOUTHWELL—ANOMURA 107
might be initiated, even though some of the genera are certainly very nearly related.
The descriptions given of many species of Porcellana are much too short to be of
any real value, and render the work of identification not only unsatisfactory, but
almost impossible. No doubt, however, much of the difficulty referred to above
has been due to the difficulty of access to necessary literature.
During the examination of this Kutch collection I have had the inestimable
advantage of being so situated that by far the most of the species recorded in this
paper have been accessible to me in quantity, and in a living condition, from the
Ceylon Pearl Banks.
No fact has struck me so forcibly during the examination of this collection, as
the extent of the variation characteristic of many species. Some species within a
genus may be distinguished as being more stable than others. Spines are particularly
liable to variation ; so, in less degree, are colour markings. Many of these variations
are noted in the text. This fact serves to indicate how inaccurate may be descriptions
of new species made from a very few specimens—and possibly young forms.
I cannot close without expressing my indebtedness to Mr. Hornell for his help
in many ways, for placing this collection in my hands, and for providing opportunities
for studying fresh material under conditions in which it was a pleasure to work.
ANOMU RA.
PAGURIDES.
Famity : PaGurgip.
Pacurip#: Dana (7), Stimpson (34), Henderson (19), Stebbing (33), Ortmann
(29), Bouvier (6), Milne-Edwards and Bouvier (10), Alcock (2).
Pacuroip# : Boas (5).
PaRAPaGuRID&: Smith (31), Henderson (19), Stebbing (33).
Diogenes, Dana.
Dana (7), Stimpson (34), Heller (16), Haswell (14), Henderson (19), Stebbing
(33), Ortmann (29).
This genus is confined to shallow water, and is characteristically Indo-Pacific.
There are about thirty species, three of which occur along the shores of the Atlantic,
one in the Mediterranean (solely), and the rest are purely Indo-Pacific. Many of the
species are small and very variable. The outstanding features which characterise the
genus are as follows :—
108 OKHAMANDAL MARINE ZOOLOGY REPORT
Abdomen soft, coiled, and well developed. Carapace elongate. Hye-stalks
slender. Ophthalmic scales large and separated by a movable rostrum. Antennal
acicle well developed, with the flagellum usually setose.
Chelipedes dissimilar, the left being much the greater. The fingers move in an
oblique direction and have their tips calcareous and acuminate. The palp of the first
pair of maxilla has a recurved flagellum. Fourth pair legs subchelate, fifth pair
chelate, both with corneous granules on their distal outer surface. Abdominal
segments four in number, and situated on the left side, uniramous in the male and
biramous in the female, except in the last one. The gills are phyllobranchs, and are
thirteen in number on each side.
Diogenes investigatoris, Aucocx.
Carapace fairly elongate, with the anterior and lateral edges serrulate.
Rostrum a simple non-serrated rod, tapering towards the free extremity, and equal
in length to the ophthalmic scales. These latter have their free edges spinulose. Kye-
peduncles shorter than the antero-lateral border of the carapace and reaching to the
base of the terminal joints of the antennal and antennular peduncles. The antennal
flagellum is slightly shorter than the carapace, and is coarse and setose. The antennal
acicle does not overlap the base of the last joint of the peduncle. Left chelipede
very much larger than the right, and a little longer than the carapace.
The outer surface of the hand is granulous, and there is a row of spines on the
upper part of the outer surface of the palm. The legs are setose along their edges
only and smooth elsewhere.
Three apparently young male specimens inhabiting shells of Nassa glans and
Sistrum spectrum.
Length of carapace, 9 mm. ; colour in spirit, dirty white.
Localities :—(1) Okha, 5 fms. ; (2) off W. coast of Aramra.
Previously recorded from :—(1) Off Vizagapatam Coast, 20fms. Alcock. (2)
Ceylon Pearl Banks, 5 fms. Southwell.
Clibanarius, Dana.
Dana (7), Stimpson (34), Heller (17), Miers (26), Haswell (14), Henderson (19),
Milne-Edwards and Bouvier (10), Stebbing (83), Ortmann (29).
Carapace elongate, broadened posteriorly, and calcified in front of the cervical
groove, as in many other genera of Paguride. Rostrum short and distinct.
Abdomen soft and spirally coiled.
Eye-stalks slender. Ophthalmic scales usually closely approximated. Antennal
acicle short. Antennal flagellum long and non-setose. Exopodite of the three
SOUTHWELL—ANOMURA 109
maxillipeds have each a well-developed flagellum. The endopodite of the first
maxille has a recurved flagellum.
Chelipedes usually similar and equal, or one may be slightly larger than the other.
The fingers open and close in a horizontal plane, and their tips are corneous and
spooned. The fourth and fifth pair of legs have a patch of thickened corneous
granules on the outer surface near the tip.
No paired appendages in either sex, except those which form the tail fin.
Biramous appendages are found on the left side on segments 2-5 inclusive.
This genus is a large one and comprises about 53 species. For the most part
they inhabit tropical seas, but some extend into temperate waters. About half the
number of known species are Indo-Pacific forms, five species occur along the Western
Pacific Coast, ten species from the West Indies and neighbouring Atlantic Coasts,
and six species from the Coast and Islands of North-West Africa. Some are
Mediterranean. They are shallow-water and littoral forms (under 100 fathoms).
Clibanarius infraspinatus, Hitcenporr (20).
De Man (24), Ortmann (30), Henderson (18), Nobilli (28).
Carapace longer than broad, and bearing tufts of yellowish bristles, which
are most numerous near the cervical groove, whilst others occur near the lateral
borders, and on the calcified anterior part of the carapace. Rostrum very small
and barely reaching to the base of the ophthalmic scales. These latter are
small, and have their free edges spinose, setose, and approximated. Eye-stalks
long, slender and sparsely setose, slightly longer than the antennal peduncles, and
reaching to the middle of the terminal joint of the antennules. Antennal
acicle setose and triangular in shape, with spines arranged along the internal edges
and overlapping the terminal joint of the peduncle.
Chelipedes equal, similar, and very massive.
Upper and inner border of merus serrulate, and scattered vascular tubercles
occur on the outer and under surfaces. A strong tooth occurs near the lower and
inner border of the merus of the chelipedes. The extensor surface of the wrist,
hand and fingers are covered with short stout conical tubercles, many of which
bear a tuft of bristles. There is a hiatus between the base of the fingers when
closed. The fingers meet terminally in a flat blackened corneous patch on the
extensor surface. They open and close in a horizontal plane.
The second and third legs are smooth and not tuberculated, their joints are beset
with sete, and a few setz occur on their extensor surfaces. The sete are more
numerous on the dactyli.
Colour in formalin, yellowish-browun.
Eye-stalks and second and third pair of legs bear longitudinal lines of colour.
110 OKHAMANDAL MARINE ZOOLOGY REPORT
Length of carapace of largest, 3°7 cm.
Three males, one in shell of Murex tribulus.
Localities :—(1) Beyt Island E. (Balapur) ; (2) off Dwarka.
Previously recorded from:—Tavoy, Museum collector; Red Sea, Ortmann ;
Mergui, de Man and Anderson; Singapore, Walker ; Sydney, Ortmann.
Clibanarius humulis, Dawa (7).
Heller (17).
Carapace longer than broad, and well calcified in front of the cervical groove.
Rostrum very short and slender. LEye-stalks long and slender, equal in length to the
antennal peduncles, and slightly shorter than the antennular peduncles.
Ophthalmic scales short, with their free edges spinose and approximated. The
antennal acicle very slightly overlaps the base of the terminal joint of the peduncle,
and bears numerous long sete.
Chelipedes stout, equal, and as long as the carapace. Extensor surface of the
wrist and fingers studded with conical tubercles, between which sete occur. There is
a hiatus between the bases of the closed fingers, which latter are blackened and
corneous at their tips.
The second and third legs are much longer than the chelipedes, and are smooth
and sparsely setose. The propodite of the third left leg is somewhat modified, its
outer surface being a little flattened and its upper border crested. Dactyli also
slightly flattened and terminating in sharp blackened claws.
Colour in formalin, dirty white; propodites, dactyli, wrist and fingers, light
brown.
Two specimens—males.
Length of carapace of largest, 2°2 cm.
One specimen in shell of Nassa granifera.
Localities :—(1) Off Dwarka ; (2) N. coast, Beyt Island.
Previously recorded from :—Betra Par, Laccadives, Investigator; Raratonga
(West Pacific).
GALATHEIDA.
Famity: PoRcELLANIDA.
Porcellana, Lamarck.
Lamarck (21), Stimpson (34), Haswell (14), Milne-Edwards (9).
Characters of the genus :—
Carapace suborbicular, or subovate. The length usually greater than the breadth.
Frontal region prominent and dentate, the teeth usually well developed. Orbits deep.
SOUTHWELL—ANOMURA 111
Eyes usually large. Chelipedes moderately flattened. The carpus short, and usually
provided with a single projecting lobe near the proximal end of the internal margin.
The digits frequently contorted. Ambulatory limbs with the dactyli short and robust,
terminating in a single claw.
Porcellana serratifrons, Stimpson.
Stimpson (34), Southwell (32), Henderson (19).
This species (which the writer has had many opportunities of examining, both
from Kutch, and, in particular, from the Ceylon Pearl Banks, where it occurs plenti-
fully) is extremely variable, a fact which, so far as I know, has not hitherto been
sufficiently emphasised. So extensive are these variations, that it is impossible to give
more than a general description of the species.
The front is composed of three lobes, of which the median one is rounded, and
minutely serrate. The two lateral ones are much smaller, and acute, a few teeth, which
are coarser than those on the median lobe, being present on their internal edge. The
carapace is usually somewhat flattened, and is marked by a discontinuous, parallel
transverse series of pubescent strie. Edges of the carapace with a variable number
of teeth. A few spines occur over the insertion of the antennal peduncles. A little
posterior to these is a rounded lobe, bearing some small teeth. Some, or all, of the
segments of the antennal peduncles bear single teeth on their internal face. Chelipedes
equal or unequal, the left or right being the larger. The chelipedes, like the carapace,
bear discontinuous rows of pubescent strize. The inner angle of the merus is prominent
and armed with teeth. A few teeth, usually two, occur on the internal edge of the
carpus. The external edge may be entire, or bear one or two teeth.
The propodite of each chelipede bears a median dorsal carina, which may,
internally, be entire, or toothed; the outer edge always toothed. Fingers curved
and short.
Natural colour: dark uneven brownish-grey changing in spirit through brick red
to colourless.
Very numerous specimens, males and females.
Average length of carapace, 10 mm.; average breadth of carapace, 9 mm.
Loculity :—Off S.W. of Beyt Island, Gulf of Kutch.
Previously recorded from :—Hongkong, Challenger Expedition; Ceylon Pearl
Banks, Southwell.
From the examination of some hundreds of specimens, the following facts and
conclusions were arrived at :—
(1) That although the general form and outline of the carapace was consistent
throughout, particularly the form of the rostrum, innumerable minor
variations occur.
112 OKHAMANDAL MARINE ZOOLOGY REPORT.
(2) That these variations are not usually sexual variations, nor merely due to
differences of age.
(3) That the female is generally slightly broader, and of a darker colour—
particularly in spirit specimens—than the male.
(4) That the occurrence of spines is quite irregular, and not to be relied upon for
purposes of identification.
Porcellana gaekwari, n. sp.—Plate, figs. 1-3.
Carapace slightly longer than broad, convex from side to side, and from before
backwards, and marked by discontinuous, transverse striz. Lateral margins armed
with a series of spines. ‘There is a spine immediately posterior to the orbit, and one
situated over each antennal peduncle. A little further back is a rounded lobe, bearing
a few minute teeth, and posterior to this are three more spines.
The rostrum is short and deflexed, with a definite mesial furrow. It is made up of
three lobes. The median lobe is much broader, and slightly longer than the two
lateral ones. Its free edge is in the form of an exceedingly shallow V, and bears about
four to six teeth. The lateral lobes are triangular, with their inner face dentate and
their external edge entire.
Antennal peduncle long, cylindrical and three-jointed. First and third joints as
broad as long. Middle joint one and a half times longer than broad. Antennal
filament nude.
Eye-peduncle short, but extending beyond the edge of the carapace during life.
In the living condition the eyes are colourless, but pigment develops after death.
Chelipedes twice as long as the carapace in adult specimens, their dorsal surfaces
marked by transverse strize, equal or unequal, the left or the right being very slightly
the larger. Internal face of the merus minutely notched, its distal angle being
produced into a lobe. Carpus of female slightly longer than broad, with a few teeth
on its internal face, entire in the male, and sinuous.
Propodite long, and broadened distally, the posterior edge being smooth along
two-thirds of its length, but denticulate distally. Movable finger curved, with a
large tooth near its origin, and serrate along the rest of its inner border. The
three following pairs of thoracic feet are approximately two-thirds the length of the
chelipedes, and have the merus rather large, the carpus short, and as_ broad as long.
Propodus three and a half times as long as broad and hairy on its anterior surface.
Dactyli short, curved, and multiunguiculate.
Length of carapace, 8 mm.; breadth, 7 mm.; length of chelipede, 17 mm. ;
length of first thoracic leg, 10 mm.
Natural colour: ground colour milky white. Carapace with a few symmetrical
blotches of light brown. Rostrum light purple. Chelipedes similar to carapace,
but movable finger light purple. Walking legs light purple.
SOUTHWELL—ANOMURA 113
Seven specimens, one male and six females, five of the latter bearing eggs,
and one being a young specimen.
Locality :—Challai Paar, Gulf of Mannar, four and a half fathoms; bottom,
sand. Found commensal on a species of Spongodes, having dark purple tips.
This species bears a general resemblance to Porcellana serratifrons, but differs
from it very definitely in the following particulars :—
(1) The median lobe of the rostrum is slightly concave instead of rounded.
(2) The propodite of the chelipede is smooth.
(3) The dactyli of the thoracic feet are multiunguiculate.
This species appears to be related to Porcellana nitida, Haswell, but his
description is so short and incomplete that it is inconclusive.
The median rostral lobe of P. nitida is said to be “much longer than the
other,” without any further description. Moreover, Porcellana gaekwari, n. sp.,
has the rostrum spinose. The carpus of the chelipede in P. nitida has a sharp entire
internal crest. Only the males of P. gauekwari, n. sp., have the carpal crest entire.
This species is variable. The young specimen had the chelipedes only one and
a half times as long as the carapace, and equal. In others, the chelipedes were
sometimes equal, or the left or right was slightly the larger.
The spines on the internal edge of the carpus of the chelipedes of the female
were variable in number, as shown in the following table :—
Specimen. Carpus of R. Chelipede. Carpus of L. Chelipede.
1 3 spines 2 spines and many minute ones distally.
2 4 ,, 5 spines.
3 4 4 4,
4 8 4, D4,
5 — 55
6 3 4 ,,
This species undoubtedly belongs to the genus Porcellana, as defined in the
Report on Challenger Anomura.
A noticeable feature was, that in the fresh condition the eyes were non-pigmented,
the pigment only developing after death, and even then not being very pronounced.
Amongst the characteristics of this genus is the fact that the dactyli of the ambulatory
limbs terminate in a single claw, and also that the first joint of the antennal peduncle
is joined to the margin of the carapace.
Porcellana gaekwari, nu. sp., differs markedly in both these particulars. How-
ever, its general characteristics are more those of a Porcellana than of any other
genus, and it is accordingly placed here.
This species is named in honour of H.H. the Maharaja Gaekwar of Baroda, to
whose liberality is due the carrying through of the investigation of which the present
report forms part.
114 OKHAMANDAL MARINE ZOOLOGY REPORT
Porcellana tuberculosa (Mitnz-Epwarps).—Plate, fig. 4.
Petrolisthes tuberculosa, Milne-Edwards (9).
A single specimen (female) is doubtfully referred here. The description of
this species by Milne-Edwards, in his Histoire Naturelle (which is the only one
available), is very short, somewhat indecisive, and no figures are given. Milne-
Edwards’ description is as follows :—
“Carapace slightly convex, and pilose on the sides, covered with short
filigerous wrinkles, and presenting on the sides some small tubercles.
“Front deeply divided into three lobes of which the median one is
large and round, and is guttered with a profound median furrow, and the
lateral ones are straight, obtuse, and directed obliquely outwards.
Anterior feet very large. Carpus armed on the anterior edge with
several teeth, of which two are pretty large, and present above, three
longitudinal series of tubercles, separated by two furrows. Median series
most numerous and elevated. Similar tubercles on face of hands. Length
16mm. Habitat, Chili.”
The Kutch specimen agrees with Milne-Edwards’ description in the following
particulars :—
(1) The carapace is pilose on the sides and presents small tubercles
laterally.
(2) The front as in foregoing description.
(3) The carpus of chelipedes has three longitudinal dorsal series of
tubercles, separated by two furrows. Median series most numerous
and elevated.
(4) The presence of tubercles on the hands.
It differs in the following particulars :—
(1) The transverse filigerous wrinkles on the carapace are absent.
(2) The carpus of the chelipedes only armed with one tooth proximal and
internal, and another distal and external.
(3) The chelipedes are not covered with a dense down.
Assuming the species to be the same, the Kutch specimen possesses the
following characteristic points :—
(1) The palp of the third maxillipede is enormously long and hairy.
(2) The right chelipede is slightly larger than the left.
(3) The merus of each thoracic leg is characterised by being markedly
broad.
SOUTHWELL—ANOMURA 115
Milne-Edwards gives the length as eight lines (3 in.). I am unable to
determine whether this measurement is simply that of the carapace or the whole
animal.
The description of the Kutch specimen is as follows :—
Carapace slightly longer than broad, moderately flattened, and markedly tuber-
culated, with deep intervening sulci, the granular tubercles being largest towards
the anterior. Cervical grooves well marked and terminating behind each orbit.
Rostrum short, defiexed, and broadly triangular, its extremity being marked by
three large tubercles, of which one is median and advanced, and the other pair
lateral. Lateral margins of the carapace entire and hairy. Outer orbital angle
projecting. Epibranchial spines absent.. Eyes large and protruding. Hye-peduncles
short; antennules minute. Antenne projecting laterally, the first joint not extending
to the edge of the carapace, and having a crest on the distal anterior edge. Palp
of the third maxillipede very long, hairy, and extending beyond the extremity
of the antennules. Chelipedes depressed, unequal, the right one being slightly the
larger, and twice as long as the carapace.
Merus short, and roughly triangular, with a small tooth on its internal distal
angle, and a few scattered granules on its dorsal and external face. Carpus two-thirds
as long as the carapace, and half as broad as long. Its dorsal surface is marked by
numbers of tubercles of unequal size and roughly arranged in three rows, separated by
two shallow furrows. A small spine occurs proximally on its internal edge and
another one on its distal external edge. Ventral surface smooth. Propodite narrow
proximally, widening distally, and wedge-shaped from side to side, with the narrow
end external; its dorsal surface is marked by a number of tubercles of unequal size,
and roughly arranged in rows. A few short hairs occur on its external edge. Ventral
surface smooth. Fingers short, slightly curved, approximated when closed, and
tuberculated. A pad of short matted hairs occurs ventrally on their proximal ends.
The three succeeding pairs of thoracic feet equal, short, flattened, hairy along their
edges, and tuberculated along their dorsal surface. Merus very large, and almost as
long as the three succeeding joints, and three-fifths as broad as long. Carpus,
propodus and dactylus of each thoracic leg slender.
Last (fourth) pair of thoracic legs very slender, and folded along the sides of the
body, abdomen flexed under the body and slightly hairy, the hairs arising from the
edges of the terga and from isolated dorsal areas.
One female with eggs.
Length of carapace, 10 mm.; breadth of carapace, 9 mm.; length of right
chelipede, 20 mm.; length of left chelipede, 18 mm.; length of first thoracic leg,
12 mm.; length of merus of first thoracic leg, 5 mm.
Colour in formalin: milky white.
Locality :—South-west coast of Beyt Island.
116 OKHAMANDAL MARINE ZOOLOGY REPORT
Polyonyx, Stimpson.
Stimpson (34), Henderson (19), Henderson (18), Southwell (32).
Carapace suborbicular, and convex, the breadth slightly greater than the length.
Front but little produced, with an almost straight margin. First joint of the
antennular peduncle smooth. The corresponding joint of antennal peduncle greatly
elongated. Eyes of small size. Chelipedes smooth with the merus broad. Dactyli of
the ambulatory limbs short and furnished with two or more well-developed claws.
Polyonyx obesulus (Wuire).—Plate, fig. 5.
Southwell (32), Henderson (18), Henderson (19).
Carapace smooth and convex, the breadth slightly greater than the length.
Rostrum very slightly developed, obtusely rounded and deflexed in such a way that
it is not seen in a dorsal view. First segment of the antennal peduncle long.
Chelipedes equal, or the right or left the larger. Outer surface of the hand smooth.
Merus of the chelipedes has its internal distal angle produced into an entire lobe.
Carpus longer than broad. Propodite as broad as long. Fingers gaping or not, and
mostly curved. The ambulatory dactyli are triunguiculate.
Localities :—(1) Kiu, Okhamandal, low water; (2) South-west coast, Beyt
Island. One specimen from each locality.
Breadth of carapace, 8 mm. Natural colour: brownish-grey, turning red in
spirit.
Previously recorded from :—Amboina, de Man; Singapore, Walker; N. Australia,
Miers; Ceylon Pearl Banks, Southwell ; Madjicosima Is., White; Flinders Passage,
Henderson.
This species is closely related to P. biwnguiculatus, and De Man suggested
their union into one, an idea, however, which was opposed both by Miers and
Henderson.
In a former paper on the Anomura of the Ceylon Pearl Banks, I remarked that
P. obesulus and P. biunguiculatus “seem so closely related that it is difficult to
believe that they are distinct. Some of our Ceylon specimens seem intermediate
in their character.”
Since the preceding statement was written 1 have had many opportunities of
examining numbers of fresh specimens from the Ceylon Pearl Banks, where the
species occurs plentifully in shallow water, usually inhabiting the large exhalant
apertures of a species of Hippospongia, or found hidden in the cavities of rock .or
dead coral.
The two principal points in which P. obesulus differs from P. biunguiculatus
may be summarised thus :—
SOUTHWELL—ANOMURA 117
P. obesulus : P. biunguiculatus :
(1) Median frontal projection (1) Median frontal projection
obtusely rounded and prominent and acute.
but little projecting.
(2) Ambulatory dactyli_ tri- (2) Ambulatory dactyli bi-
unguiculate. unguiculate.
I am now convinced that these differences are sufficiently stable to be specific—
a conclusion arrived at after examining some hundreds of specimens of P. obesulus.
At the same time I would here remark that the aforesaid points of difference are
liable to a little variation. In one or two adult specimens of P. obesulus, with
typically triunguiculate dactyli, the rostrum was scarcely obtuse, whilst in others
it was almost straight. Again, one specimen was found with two of the dactyli
on the walking legs typically biunguiculate, and in the other specimens the small
proximal claw itself was noted to vary in size.
Polyonyx hendersoni, n. sp. (18)—Plate, figs. 6-9.
Carapace more convex from front to back than from side to side, broader
than long—the greatest breadth being anterior—smooth dorsally, but lineolate
along the posterior lateral borders. Rostrum sub-acute, rounded, only slightly
projecting, and not visible in a dorsal view. Chelipedes variable, the left or right
being the larger. Merus with a small tuberculated lobe on its distal internal face.
Carpus as broad as long, strongly tuberculated, its internal edge produced into a
rounded lobe bearing a few blunt teeth, and having a ventral entire carina. Propodus
small proximally, widening distally, the length slightly greater than the breadth,
tuberculated dorsally, smooth ventrally. Fingers curved or not, with a hiatus
between them when closed, or not. The ambulatory dactyli are four-clawed, the
terminal claw being slightly longer than the penultimate one, and the two proximal
ones being minute. Ambulatory legs bear short, matty hairs on their anterior
edge.
Length of carapace, 6 mm.; breadth ot carapace, 8 mm.
Natural colour: varying shades of brick red.
Locality :—South of Adams Bridge, Ceylon, eight and a half fathoms.
Found along with P. obesulus inhabiting the cavities of sponges, dead coral
and rock. Several specimens, males and females, many of the latter bearing eggs.
This species is the one doubtfully referred to as Polyonyx tuberculosus by
Henderson in his ‘Indian Carcinology.” After giving a short description of it
without naming it, he says, “this species is certainly distinct from P. obesulus
or P. biunguiculatus, and as de Man represents his species with the carpus smooth
above, and with very few tubercles present on the hand, our specimens may also
K 2
118 OKHAMANDAL MARINE ZOOLOGY REPORT
be distinct from P. tuberculosus. The ambulatory dactyli of the last species are
not described by de Man. I have noticed in one or two specimens of P. obesulus
a slight tendency towards tuberculation of the hand, chiefly in young individuals,
but our species may be distinguished from this variety by the greater tuberculation
and the different ambulatory dactyli. De Man had only a single small specimen,
and it may have belonged to this variety of P. obeswlus, in which case a new
name will be necessary for the form, which is here briefly characterised.”
Unfortunately, I have been unable to obtain de Man’s description of P. tuber-
culosus, but the complete tuberculation of the carpus, and propodite, of our specimens,
would almost alone be a point of sufficient distinction between the two specimens.
Many individuals of P. hendersoni, n. sp., were examined, and the tuberculation of
the carpus and propodus were found constant in every specimen. In one specimen
the dactylus of one of the thoracic legs bore four small proximal spines instead of
two. There can be little doubt, however, that P. hendersont, n. sp., is a quite
distinct species, and I have pleasure in naming it in honour of Dr. J. R. Henderson,
who first described it, and whose careful work on the Anomura in general is so well
known.
Petrolisthes, Stimpson.
Stimpson (34), Miers (26), Haswell (14), Henderson (19).
Characters of the genus :—
Carapace subovate, depressed, the length slightly greater than the breadth.
Frontal region triangular, usually depressed, with the antennal peduncle remarkably
short. Chelipedes broad and flattened, the carpus of moderate length, and often
provided with teeth on the inner margin. Ambulatory limbs with the dactyli short and
robust, terminating in a single claw.
Petrolisthes bosci (Avupourn).
Porcellana bosci, Heller (15).
Petrolisthes boscw, de Man (25).
Porcellana rugosa, Milne-Edwards (9).
The front is prominent, triangular and deflexed, presenting a median furrow. The
carapace is depressed, and slightly longer than broad. Margins entire and terminating
anteriorly in an acute epibranchial spine. The surface is marked by a very noticeable
mosaic, and by the strong development of granulate, filigerous, elevated, irregular lines,
which are visible to the naked eye. Chelipedes equal, and beautifully sculptured like
the carapace. The merus is armed with three spines at its distal extremity, one
internal, one external, and one ventral and median. Carpopodite armed internally
with a varying number of large spines (usually three or four), and externally with a
SOUTHWELL—ANOMURA 119
serrate crest, arising about the middle of its length, and increasing in size distally.
Ventrally and internally the carpus bears an entire carina. Carpus twice as long as
broad, and slightly shorter than the carapace. The fingers are straight, and there is no
hiatus between them when closed. The ambulatory legs are slightly hairy, the carpus
robust and flattened.
Colour in formalin, a lovely and characteristic mosaic of mottled maroon.
[t is interesting to note that no mention whatever is made of the natural colour
either by Henderson in his Contribution to Indian Carcinology (18), or by de Man
in the Crustacea of the Mergui Archipelago (24). I have been unable to obtain
Audouin’s original description. However, these colour markings are most
characteristic, and quite different in nature from anything I have previously seen.
The Kutch specimens were preserved both in formalin and in spirit, and in neither
case have the colours suffered any change, even after the lapse of two years.
This species appears to be closely related to P. dentata (Milne-Edwards), from
which it differs in the peculiar and stronger development of the filigerous lines along
the carapace, and also in the inner margins of the fingers being hairy, and the spine
on the upper exterior margin of the merus being acute and not obtuse.
Two specimens, one male and one female.
Dimensions :—
Kutch specimen. De Man’s specimen.
Length of cephalothorax 14 cm. 8} mm.
Breadth ,, 3 1°32 5 8,
Length of carpopodite 10 ,, 52
From these measurements it will be noticed that the Kutch specimens are very
large, being approximately two-thirds larger than those examined by de Man.
I have observed this species living in the cavities of certain sponges, and on the
branches of Spongodes, sp., on the Ceylon Pearl Banks.
Locality:—Hanuman Dandi Reef, Beyt.
Petrolisthes armatus ? (Giszes).—Plate, fig. 10.
Porcellana armata, Gibbes (12).
Petrolisthes armatus, Stimpson (34 and 35).
I doubtfully refer a damaged specimen of this genus to the species armatus, not
being able to refer to Gibbes’ original description, or to Stimpson, and no figure being
available. The carapace is slightly flattened, longer than broad, and glabrous. There
is no epibranchial spine. The front is broadly triangular and round, deflexed with a
mesial furrow. The eyes are large. The chelipedes are equal, and two and a half
times as long as the carapace. The merus has a short acute spine at its internal distal
angle, and another one ventral and external. The carpus is almost as long as the
carapace, and bears three teeth along its internal face, and a ventral internal and
120 OKHAMANDAL MARINE ZOOLOGY REPORT
external crest. The palm is broad and round, outer surface of hand not serrate.
Fingers acute, curved and shorter than the palm, with a small hiatus between them
when closed. Ambulatory legs missing. Colour in spirit : dirty milky white.
Locality :—South of Chindi Reef, Gulf of Kutch, 6-10 fathoms.
It is a Floridian and West Indian species, but has also been recorded by the
Challenger, and from the Ceylon Pearl Banks.
Petrolisthes, sp.
A damaged specimen in the collection is referred to this genus. Carapace
slightly longer than broad, a little compressed, surface marked with pubescent strie,
the hairs being short. Lateral margins entire, and slightly hairy. Superior orbital
border straight, with a blunt external orbital projection. Rostrum prolonged deflexed,
with a shallow median furrow, and the edges crenulate. Eyes large. Eye-peduncles
short. Antennules minute. First joint of antennal peduncle reaching beyond margin
of carapace. Chelipedes absent. Ambulatory legs short. Merus broad.
Length of carapace, 5 mm.; breadth of carapace, 5 mm.
Colour in formalin: milky white.
Locality :—South-west of Beyt Island.
Galathea, Fasrictus.
Galatea.—Leach (23), Desmarest | Galathea.—Fabricius (11), Milne-
(8), Latreille (22), De Haan (18), Edwards (9), Dana (7), Heller (16).
Stimpson (34), Haswell (14). |
Rostrum flattened, and of moderate breadth, with the margins usually spinose.
Carapace with pubescent transverse strie, the surface usually unarmed, with the
exception of the anterior gastric area. The cardiac area not prominent. Abdominal
segments unarmed.
The members of this variable genus are usually confined to shallow water,
where they live symbiotic on crinoids, or amongst coral, or on the surface and
crevices of rocks. They swim backwards by curious movements of the tail.
The genus is more or less cosmopolitan.
Galathea elegans, Wuirs.—Plate, fig. 11.
Adams and White (1), Henderson (19), Miers (27).
Rostrum very long, and acute, two-thirds the length of the carapace and armed
with seven small teeth on each side. Carapace and abdomen covered with a continuous
series of pubescent strie, and rather more than half as broad as lovg (including
the rostrum). Lateral margins of the carapace armed with about eight teeth.
SOUTHWELL—ANOMURA y 121
Antenne minute. Antennal pedunéle slightly elongated, the joints bearing acute
spines on their anterior and posterior faces.
Chelipedes slender, one and two-thirds longer than the carapace and rostrum,
and bearing a few spines. Fingers not gaping, and not half the length of the
propodus. Colour yellowish, with three longitudinal dark purplish bands on the
carapace, and one on either side of the chelipedes and legs.
One female bearing eggs.
Length of carapace and rostrum, 13 mm. ; breadth of carapace, 7 mm. ; length
of chelipedes, 22 mm.
This species was found commensal on a species of black and white coloured
Antedon.
Locality :—South-west of Beyt Island.
Previously recorded from:—Holborn Island, Haswell; Ceylon Pearl Banks,
Southwell; Celebes Sea, Henderson; Borneo, Adams and White; Singapore, Walker ;
N. Australia, Haswell-Miers ; Amboina, de Man.
Munida, Leacu.
Leach (23), Desmarest (8), Dana (7), Bell (4), Stimpson (34), Heller (16),
Miers (26).
Rostrum slender and stiliform, with a well-developed supra-orbital spine on either
side of the base. Carapace with the surface usually spinulose, and the cardiac area, as
a rule, distinctly circumscribed.
Chelipedes and ambulatory limbs elongated and slender. One or more of the
abdominal segments usually with a series of spinules on the antero-dorsal margin.
Very many members of this genus are deep-sea forms, extending down to
1,300 fathoms. A few are littoral, and occur in the crevices of rock or coral.
Munida spinulifera, Miers.—Plate, fig. 12.
Henderson (18), Miers (27).
Carapace a little elongated, and covered with a series of more or less continuous
pubescent strie. Edges of carapace armed with seven or eight spines. Rostrum a
slender, conical, elongated, entire rod. Behind the rostrum, on each side, are four
large spines, slightly less than the rostrum, and decreasing in size posteriorly. Eyes
fairly large, and overhung by a few sete. Peduncles rather short. Chelipedes long
(twice as long as the carapace, including the rostrum), slender and hairy. The merus
is elongated and bears three spines on its internal edge, and a few smaller ones on its
outer edge. Carpus shorter than the merus, with one large spine on its anterior edge,
and a row of about four smaller ones on its outer surface. Propodite as long as the
fingers, with a number of smaller spines on both its inner and outer edge. Fingers
gaping. Abdomen unarmed,
OKHAMANDAL MARINE ZOOLOGY REPORT
Several specimens, males and females. Natural colour: brick red.
Length of carapace and rostrum, 6mm. ; length of carapace, 3°5 mm. ; length of
chelipedes, 11 mm.
YW WW WwW bp
Ww
PO Ss SP eee Woot
Localities :-—(1) 8.W. of Beyt Island; (2) §. of Adams Bridge, Ceylon.
Previously recorded from :—Amboina (Henderson) ; Arafura Sea (Miers).
INDEX TO LITERATURE CITED.
The numbers preceding the names are those by which the papers are referred to im the text.
Adams and White. Zoology of the “ Samarang,” Crust., Pl. XII., Fig. 7, 1848.
Alcock. Catalogue of Indian Decapod Crustacea, Part II., Anomura, fase. i, Pagurides.
Calcutta, 1905..
Alcock. Descriptive Catalogue of Indian Deep Sea Crustacea. Calcutta, 1901.
Bell. Brit. Crust., 1853.
Boas. Vidensk. Selsk. Skr. 6 Raekka, Naturvid ag math. Afd. 1. 2, 1880.
Bouvier. Fewille des Jeunes Naturalistes, June-July, 1896.
Dana. U.S. Lxplor.-Expedition, Crustacea, Part I, 1852.
Desmarest. Consid. sur les Crust., 1825.
H. Milne-Edwards. Histoire Naturelle des Crustacés. Paris, 1837.
Milne-Edwards and Bouvier. (Part) Crustacea Hirondelle et Princesse Alice. Monaco, 1899.
Fabricius. Suppl. Ent. Syst., p. 414, 1798.
Gibbes. Proc. Amer. Assoc., 1850.
De Haan, Crust. Japonica, 1850.
Haswell. Catalogue of Australian Crustacea. Sydney, 1882.
Heller. Sitzungsber. der Wiener Akad. de Wissensch., Bd. XLIV.
Heller. Crust. Sudl. Hurop., 1863.
Heller. “ Novara” Crust., 1865.
Henderson. rans. Linn. Society, (2) Vol. V. Zoology, 1893.
Henderson. “ Challenger” Anomura, 1888.
Hilgendorf. In V. D. Decken’s Reisen Ost. Afr., III. 1, 1869.
Lamarck. Syst. des anim. sans vert., 1801.
Latreille. Sam. Nat. du Regne Anim., 1826.
Leach. Dict. d. Sci. nat., t. XVIII., 1820.
De Man. Journal Linn. Society, Zool., Vol. XXII., 1888.
De Man. In Notes from Leyden Museum, Vol. III.
Miers. Catalogue of New Zealand Crustacea. London, 1876.
Miers. Crustacea of II.M.S. “ Alert,” British Museum, London, 1884.
Nobilli. Bull. Mus. Vorino, XVIIT., 1903.
Ortmann. In Bronn’s Thier-reich, Malacostraca.
Ortmann. Zool. Jahr. Syst., VI., 1892.
Smith. Bull. Mus. Comp. Zool. Harvard, X., 1883.
Southwell. Anomura, in Ceylon Reports, Vol. V., 1906.
Stebbing. Hist. Crust., 1893.
Stimpson. Proc. Acad. Nat. Sci. Philad., 1858.
Stimpson. Lyc. Nat. Hist. New York, Vol. VIL, 1859.
a
Oe SOON ee?
10a.
ee
no —
SOUTHWELL—ANOMURA 123
EXPLANATION OF PLATE.
ANOMURA.
Porcellana gaekwari, n. sp. X 3.
Right chelipede of same. x 5.
Dactylopodite of second right walking leg of same. xX 17.
Porcellana tuberculosa, M. Edw. x 24.
Polyonyx obesulus (White). x 24.
Polyonyx henderson, n. sp. Xx 2.
do. outline of rostrum.
do. right chelipede. x 24.
do. dactylopodite of second walking leg, greatly enlarged.
Petrolisthes armatus (Gibbes), body without legs. x 2.
Chelipedes of same. x 24.
Galathea elegans, White. x 2.
Munida spinulifera, Miers. xX 34.
MARINE ZOOLOGY oF OKHAMANDAL.
G. Henry del.
ANOMURA OF OKHAMANDAL
ANOMURA, PLATE.
Eee
Luge
rR Be
Edwin Wilson, Cambridge
REPORT
ON A
COLLECTION OF ALCYONARIANS
OKHAMANDAL IN KATTIAWAR
MADE BY MR. JAMES HORNELL IN 1904-5,
BY
PROF. J. ARTHUR THOMSON, M.A.,
AND
GEORGE CRANE, B.Sc., University of Aberdeen.
[With one Plate! and two Text-figures. ]
In the course of an investigation of the shallow-water fauna of part of the
Gulf of Kutch, Mr. James Hornell made a small collection of Alcyonarians which
presents some features of interest. The precise district was the coast of Okhamandal,
which forms the N.W. extremity of the Kattiawar Peninsula, and Mr. Hornell
has called our attention to the fact that specimens of Dendronephthya or Spongodes,
of Lophogorgia, Astromuricea, etc., could be collected at low tide.
The collection includes eight species, one of which—Astromuricea stellifera—
is new. There is also a new variety of a remarkable species of Hchinomuricea
previously found in the Indian Ocean. The position of the various species may
be indicated as follows :—
ORDER ALCYONACEA.
Family Alcyonide: 1. Sclerophytum polydactylum (Ehrenberg).
Family Nephthyide: 2. Dendronephthya (Spongodes) dendrophyta (Wright and
Studer).
3. Dendronephthya (Spongodes) brevirama (Burckhardt).
1 The artist’s fee for drawing the specimens on this plate was paid by the Carnegie Trust for the
Universities of Scotland, and J wish to thank the Trustees for helping me on this and other occasions to
give worthy illustrations of the beautiful animals described.—J.A.T.
125
126 OKHAMANDAL MARINE ZOOLOGY REPORT
ORDER AXIFERA.
Family Muriceide: 4. Astromuricea stellifera, n. sp.
. Echinomuricea uliginosa, Thomson and Simpson, var.
on
‘
tenerior n.
Family Gorgonide: 6. Lophogorgia lutkent, Wright and Studer.
. Juncella juncea (Pallas).
vy
ORDER STELECHOTOKEA. Section Pennatulacea.
Family Virgularide: 8. Virgularia rumphi, Kolliker.
ORDER ALCYONACEA. FAMILY ALCYONID.
1. Selerophytum polydactylum (Ehrenberg).
PuateE, fig. 5.
= Lobularia polydactyla, Ehrenberg.
= Aleyonium polydactylum, Dana.
For description see :—
Klunzinger: Die Koralithiere des Rothen Meeres, Part I. 1877, p. 26; Pl. I. figs. 6a—6f
Pratt: The Alcyonaria of the Maldives, Part II. 1903, p. 524.
Several fine specimens are referable to this species, which is characterised
by the absence of siphonozooids, the small size of the autozooids, and the tough,
fleshy texture.
The largest specimen has the following dimensions: height, 5 cm.; length,
14 cm.; breadth, 8 em. The lobes are much less digitiform than those figured
by Klunzinger, being broader and flatter.
No autozooids occur on the stalk. They are most crowded towards the tips
of the lobes. From ten to twelve may be counted on a linear centimetre.
The spicules closely resemble those figured by Klunzinger; the average
size of the large warty spindles is 15 mm. by 0°3 mm., and of the small clubs
0°08 by 0°02 mm.
The colour of the colony is greyish-brown, and the surface, under the low
power, has a peculiar reticulate appearance due to the presence of small superficial
spicules.
Localities :—The specimens were obtained off Beyt Island, from Adatra Reef,
and from Chindi Reef.
Previously recorded from :—The Red Sea, Maldives, Gulf of Mannar, Zanzibar,
China Sea, British New Guinea.
THOMSON AND CRANE—ALCYONARIANS 127
FAMILY NEPHTHYID.
2. Dendronephthya (Spongodes) dendrophyta (Wright and Studer).
Puate, fig. 4.
For description see :—
Wright and Studer: Spongodes dendrophyta. Challenger Report, Vol. XX XI. 1889, pp. 204,
205; Pl. XXXVI. c, fig. 2a, 20.
Studer: Aleyonarien aus der Sammlung des Naturhist. Museums in Liibeck, 1894, p. 127.
See also Kiikenthal, Versuch einer Revision der Alcyonarien. II. Die Familie der Neph-
thyiden. 2 Teil. Zool. Jahrb. xxi. (1905), p. 647, fig. 39.
Numerous umbellate specimens showing considerable diversity in size and
appearance may be referred to this species. Several are of the open, loosely
branching type, figured in the Challenger Report, but the majority have the polyps
close-set and almost continuous on the surface of the polyparium as shown by
Kiikenthal. All are of an ovoid shape, markedly flattened from side to side. Typical
dimensions are: height, exclusive of the stalk, 5 cm.; diameter, 4 cm. and 2 em.;
height of stalk, 4-5 cm. The largest specimen has a polyparium 7 cm. high, with
diameters 6°5 cm. and 3 cm., and a stalk 2°5 cm. in height. The length of
stalk varies considerably. There is a central axis from which spring several lateral
branches ; these again subdivide two or three times and give rise to the polyp-bearing
twigs. The twigs are grouped in fours or fives, and each bears about a dozen polyps.
Even in the loosely-branched types the polyps are all borne on the surface of the
polyparium, and immediately below those on the top of the stalk there are occasionally
isolated twigs with a few polyps. Some of the lower branches are leaf-like.
The polyps are 0°55—0°6 mm. high and 0°6—0‘7 mm. broad, with a stalk of
about the same height as the polyp. The spicules on the polyps are arranged in eight
double rows, each row containing usually four, but frequently five curved spicules
(up to 0°24 mm. in length). The uppermost spicules of the rows do not project.
The Stiitzbiindel contains two rows of long warted spindles (2 mm. long), the upper-
most projecting about half its length. On the superficial layers of the branches
there are numerous long warty spindles (1'22 x 0°l1 mm.), and the x-shaped spicules
noted by Wright and Studer are also very numerous (0°17 mm. in diameter).
Reproductive bodies—probably sperm-sacs—occur in great abundance. ‘The
largest of these is 0°25 mm. in diameter. They are attached to the mesenteric bands
far below the polyp stalks. The specimens were collected in the month of December.
Locality:—Rann Bay east of Poshetra, Okhamandal. Also off Kiu, Beyt
Harbour.
Previously recorded from :—Chinese Sea and the Philippines.
128 OKHAMANDAL MARINE ZOOLOGY REPORT
3. Dendronephthya (Spongodes) brevirama (Burckhardt).
PuatE, fig. 6.
For description see :—
Burckhardt, E.: Alcyonaceen von Thursday-Island (Torresstrasse) und von Amboina. Semon’s
Zool. Forschungsreisen, vol. 5 (1898), p. 438, Pl. 31, fig. 5; Pl. 32, fig. 3a—3e.
Kiikenthal, W.: Versuch einer Revision der Aleyonarien. II. Die Familie der Nephthyiden.
2 Teil. Die Gattungen Dendronephthya n.g. und Stereonephthya n.g. Zool. Jahrb. xxi.
(1905), p. 659.
Several specimens of a distinctly umbellate type, with close-set polyparium
somewhat flattened and presenting a continuous surface, are referable to
Kiikenthal’s florida group of Umbellate, and agree in essential features with
Burckhardt’s Spongodes brevirama. Most of them vary in height from 3 cm.
to 5 em., exclusive of the short stalk portion, which is usually about 1 cm. in
height, somewhat flattened, and with root-like attachments. In the smaller specimens
the polyparium is almost hemispherical, in the larger forms it tends to be ovoid.
It cannot be said that the polyparium is greatly flattened; in one specimen the
diameters were 4 cm. and 2°7 cm., in another they were 4°5 cm. and 35cm. The
collection also includes a very fine specimen ovoid in form and markedly flattened,
with the following dimensions: height of the polyparium, 12°5 cm. ; diameters, 10°5 cm.
and 5 cm. The stalk is practically suppressed, being reduced to about 1 cm. in height.
The average length of the root-like attachments is 6 cm.
The lowest branches are very distinctly leaf-like in many of the specimens
but not in all. Above these there are numerous approximately cylindrical main
branches arising on all sides from a continuation of the stem. The main branches
give off secondary branches, and these again give rise to the polyp-bearing twigs.
The number of polyps borne by each distinct twig is very variable, but there are
usually many bundles of about six each. The polyp-stalks are very short, and
the polyps are confined to the surface of the polyparium. They are almost
uniformly disposed on all sides. This is not in agreement with one of the
features of the florida group, in which, according to Kiikenthal, there is denser
and more uniform distribution of polyps on the flatter surfaces. It does not
seem to us necessary to attach much importance to such differences, which
probably depend entirely on growth conditions. A feature of some interest on
several specimens is the occurrence of a number of small twigs on the short stalk
portion, almost down to the level of the stolons. Each twig bears two or three
polyps.
The polyps are from 0°6 to 0°7 mm. in height by 0°5 mm. in breadth, and
the stalks are about 0°8 mm. long. There are eight double rows of spindles on
each polyp, each row containing five to seven spicules, the uppermost of which
projects slightly. The spicules in each double row are arranged en chevron, and
THOMSON AND CRANE—ALCYONARTIANS 129
the average size of the spicules is 0°14 by 0°03 mm. The single large Stiitzbiindel
spicule is strongly warted and is 1°8 mm. long by 0°08 mm. broad. It projects
for about half its length. The superficial layers of the stem and stalk contain
many large warty spindles (up to 2°6x0'2 mm.) and numerous smaller ones
(0°8 x 0:06 mm.). The spicules of the canals are for the most part warty spindles
(0°62 x0°L mm.) and a few smaller forms (0°17 x 0°05 mm.) which approximate
to the stellate type.
Fic. 1.—Dendronephthya brevirama, showing close-set polyparium and
anchoring stolons.
The colour of most of the specimens is a yellowish white, but mdividual
polyps and even individual spicules of a deep rose-pink colour are found scattered
here and there in the polyparium.
Localities :-—S.E. of Beyt, 2-4 fathoms; Balapur Bay, low tide, and Maneunda
Reef, Gulf of Kutch.
Previously recorded from :—China Sea and Torres Strait.
130 OKHAMANDAL MARINE ZOOLOGY REPORT
ORDER AXIFERA. FAMILY MURICEID/.
4. Astromuricea stellifera, n. sp.
PraTE, figs. 1, 2, 3.
Some beautiful red fans, with the characters of the genus Astromuricea, seem
to require the establishment of a new species. Of the three specimens examined
the largest is 14cm. in height, and 28em. in breadth. From a basal trunk (1°5 cm.
high and 7 mm. thick) two main branches diverge, each giving rise to a flabellate
system. The smaller of the two gives off a third fan parallel to the others, with
which it anastomoses at several points. The colony is attached by a basal disc
about 2cm. in diameter. The main branches are 4mm. in thickness, the larger
is 25cm. long and the smaller 15 cm.
A second specimen is 8cm. high by 14 broad, with three main ‘branches.
The third specimen is somewhat incomplete, forming one-half of a fan 10cm. high,
with three main branches.
The branching is frequent, mostly alternate, and in one plane. The larger
branches arise at an angle of about 60°, but this angle is often exceeded, and most
of the smaller branches form an angle of 90°. Anastomosis is frequent among both
large and small branches. The branches vary from 1 to 2mm. in diameter, the
smaller twigs being often slightly swollen at the tips. The colony is very flexible
and not at all brittle.
The axis is horny, solid at the base, and hollow in the branches, of a dark
glossy brown colour and almost smooth.
The verruce are closely crowded, and occur on all sides of the stem and branches,
but in no regular order. In two of the specimens they project but little from the
surface of the coenenchyma; in the third they project for about half their diameter.
They are cylindrical in shape, with a diameter of from 0°5 to 1mm. On their
summit there is a circular aperture fringed by about a dozen projecting spiny spicules,
similar to those with which the wall of the verruca is covered. The anthocodiz
are completely retractile within the mouth of the verruca. There is a low, almost
horizonta] operculum, formed by the convergent tentacles with their armour of
spicules. On the aboral side of each ‘tentacle lie two spicules converging towards
the tip of the tentacle to form a very narrow isosceles triangle. Round the base of
the tentacle there is a single or double ring of spicules.
The coenenchyma is moderately thick, and its surface presents under the lens
a characteristically rough appearance. -
The spicules of the coenenchyma are (1) numerous irregular warty stars and
stellate toothed plates, 0°14—0°28 mm. in diameter ; (2) a few stout spindles with close-
set tuberculate warts of which the following measurements were taken: (length and
THOMSON AND CRANE—ALCYONARIANS 131
breadth in millimetres) 0°21 x 0°035, 0°23 x 004; 0°24 x 0°08, 0:28 x 0:05, 0°31 x 0°06,
0°45 x 012; (8) small forms—probably young—somewhat irregular in shape, but
resembling the types just described, mostly about 0°12mm. in length.
These spicules are of a fine pink or rose-red colour. A few are colourless.
In the polyp the spicules seem to be confined to the operculum. They are long
slender white spindles, somewhat bent, and bearing a few warts. They are from
0°14—0°18 mm. in length and 0°012—0-024 mm. in breadth.
The colour of the colony is between Venetian red and crimson and the polyps
are white. Reproductive bodies were present in many of the polyps.
A stellifera may be distinguished from the other three species of Astromuricea
by the character of the spicules fringing the mouth of the verruca. They do not
exhibit any specially long needle-like processes as in the other species.
Locality :—Kiu, Beyt Harbour, low water, 24/12/05; also dredged off S.W.
coast of Beyt Island.
5. Echinomuricea uliginosa, Thomson and Simpson (1909), var. tenerior, n.
PuateE, figs. 9, 10, 13.
The Investigator collection of littoral Indian Ocean Alcyonarians includes a
new species of Echinomuricea (E. uliginosa) which is described in detail by
Thomson and Simpson in a memoir just about to be published. A variety of
this species occurs in Mr. Hornell’s collection.
The diagnosis of the species is as follows: A pinkish-red colony branched in
one plane; the coenenchyma is thick and very rugose with spicules projecting in
all directions; the verrucee are ‘thickly disposed, covering most of the surface;
their walls bristle with the long smooth spines of projecting spicules; there is an
elevated conical operculum composed of eight groups of three spindles and a
collaret of two or three rows of transversely arranged curved spicules; each
“point” consists of two bent spindles which touch for over three-quarters of their
length but diverge near the collaret, the interspace being almost completely filled
by a short, curved, transversely disposed spindle; the horny axis is brown,
cylindrical, and chambered, firm and flexible below, soft and collapsible above ;
the spicules include a variety of forms, (a) some showing a projecting smooth
spine with branching warty arms at the base, (b) spindles covered with irregular
warts, (c) spindles bearing in addition to warts a number of smooth projecting
spines on one side, (d) irregular forms with warty branches on one side and smooth
spines on the other, (e) bifurcated spindles, (f) irregular plates with warty branches,
and (g) smooth spindles in the anthocodie.
Locality :—Laccadives (Kalpeni Bank) and Arakan Coast, 13 fms.
The specimen from Kutch is a small unbranched colony, 65 mm. in height by
3 mm. in diameter. It is more delicate in appearance than the typical Echinomuricea
L
132 OKHAMANDAL MARINE ZOOLOGY REPORT
wligiosa and liehter in colour, This is especially noticeable in the case of the
large pointed spicules surrounding the mouth of the verruca, these being deep red
t
ig to white at the tip in the variety. The ground
ts)
in the typical form, pink changu
colour of the coenenchyma is white in the variety, red or pink in the type.
As to spicules, those of the variety are somewhat more delicate than those
of the type, and bear longer spines. The chief difference between the variety
and the type is that the superficial spicules of the coenenchyma im the variety
ave white spindles, with prominent rough warts, and reaching dimensions of
061x019 mm., while the corresponding spicules in the type are thick red
spindles with short close-set warts, and of larger size, viz., 0°91 x 0°23 mm.
Locality -—Off Dwarka, 16 fms.
FAMILY GORGONID.
6. Lophogorgia lutkeni, Wright and Studer.
Prats, fig. 11.
Challenger Report, xxxi. 1899, p. 150, Pl. XXX. fig. 1, La, XXXIV. fig. 1.
The collection includes several large and fine specimens of this species. The
colonies are more copiously branched than the description in the Challenger Report
Fic, 2.—Gorgonids (Lophogorgia lutkent and Astromuricea stellifera) exposed at low
water, Kiu, near Beyt.
secins to incheate, and the largest Beyt specimen is about double the height of that
Paar E ‘ 1 : : i
obtained by the Challenger. The diameter of the main stem on the largest specimen
gest specime
is about lem., and the height of the colony is 45em. There is much variety in
ov
THOMSON AND CRANE—ALCYONARIANS 133
the conspicuousness of the verruce, for while in some places they stand out to the
height of 1mm., in others the openings are flush with the general surface. Under
the low power the slit-like openings of the verrucee show eight triangular lobes
which cover the retracted tentacles. The verruce are uniform in size, with a long
diameter of about 1°5 mm,
The spicules are on the whole smaller and more uniform than those in the
Challenger specimen, the warty spindles being on the average 0°1 x 0°05 mm.
Locality :—The channel west of Beyt Island, 3-4 fathoms.
Previously recorded from :—Off Prince Edward Island, Ceylon, and Zanzibar.
7. Juncella juncea (Pallas).
Prats, fig. 14.
Gorgonia juncea, Pallas. Esper: Die Pflanzenthiere, 1797 ; Fortsetzwng, p. 177, tab. lii.
Juncella juncea. Valenciennes, Comptes Rendus, xli. p. 14.
See Wright and Studer: Challenger Report, xxxi. 1889, p. 158, Pl. XXXIV. fig. 12.
Several specimens in this collection seem referable to this species. As Professor
Hickson points out, there is great difficulty in distinguishing between Juncella
juncea and Juncella gemmacea, since they agree in the prominence of the verruce,
the thickness of the coenenchyma, the slight branching, and the nature of the
spicules, which consist of clubs and double stars.
Ridley also calls attention to the slightness of the distinctions separating some
of the species of Juncella, and the great variability in the characters.
Perhaps, as Professor Hickson suggests, J. junceaw and J. gemmacea should
be included in one rather variable species.
The present specimens are fragmentary, all except one unbranched. The
verrucs: are very crowded, agreeing with Pallas’s description. The largest specimen
is 42cm. long and varies from 7 mm. to 1‘5mm. in diameter. There is no definite
arrangement of the verruce.
The colour of the branched specimen is yellowish-white, with a touch of red
in some of the verruce. The other specimens have a buff colour.
The spicules consist of clubs and double stars with intermediate forms which
show clearly the passage of the club into the double star. A few single stars
were also found.
The following measurements were taken :-—
Double stars—0°07 x 0°03 ; 0°09 x 0035 mm. ; 0°09 x 0°04 ; 0'1 x 0°04.
Clubs—0-08 x 0°025 ; 0°08 x 0°05 ; 0°09 x 0°03.
Single stars—0‘04 mm. diameter.
Localities :—South end of Beyt Island, 3 to 4 fathoms; off Poshetra Point.
7 fathoms.
Previously recorded from :—Ceylon, Queensland, &c, ;
L
134 OKHAMANDAL MARINE ZOOLOGY REPORT
ORDER STELECHOTOKEA. SECTION PENNATULACEA.
8. Virgularia rumphii, Kolliker.
PuaTE, figs. 7, 8, 12.
Kolliker: Die Pennatuliden, 1872, p. 202, figs. 123, 124.
Two specimens are referred to this species although showing certain departures
from the type. The divergences seem to us to be merely quantitative. There is
a long bare streak on the prorachidial surface, and a similar streak on the metarachidial
surface, obscured, however, at the top by the interlocking pinnules.
The pinnules are
close-set. They have crowded polyps, a wavy outline, and the peculiar interlocking on
the dorsal surface shown in Kélliker’s figure.
The axis is cylindrical below and
flattened dorso-ventrally above. The calices of the polyps are indistinct, and thus very
different from those of V. multicalycina, Thomson and Henderson.
The specimens differ from Kélliker’s description in having a larger number
of polyps on each pinnule (70 and 55 instead of 40—44).
Siphonozooids cannot
be clearly recognised, but this may be due to the imperfect preservation of the
specimens. The superficial ramification of the canals on the prorachidial surface
is only hinted at. The axis is more slender in our specimens than
description.
The following are the chief measurements :
in Kolliker’s
SPECIMEN 1. SPECIMEN 2. KO6LLIKER’s.
Total length 252 mm. 140 mm 523 mm
Length of rachis . 211 =, 104 ,, 422 ,,
Length of stalk . i 41 ,, 36 OC, 101 ,,
Breadth of pinnule-bearing part Dy, de 4c 6 ,,
Length of pinnules ; ae 4-6 ,, _—
Breadth of pinnules : 15-2 ,, 15, 3-35,
Number of undeveloped pinnules . 120 on each side 96 on each side 439 total
Number of developed pinnules 51 37 76+8 total
Number of polyps on each pinnule 70 55 40-44
Diameter of polyp 0-3 mm 0-2 mm —
Diameter of axis below OF x O38 ,, 39-7
Diameters of axis above 1x0°8_,, 16x1_ ,, et Does
Locality :—South-west of Beyt’ Island.
Previously recorded from :—-Amboina.
Do Oe ON eB
THOMSON AND CRANE—ALCYONARIANS 135
EXPLANATION OF PLATE.
Astromuricea stellifera, n. sp. X 10.
Astromuricea stellifera, n. sp. Nat. size.
Astromuricea stellifera, n. sp. Spicules.
Dendronephthya (Spongodes) dendrophyta (Wright and Studer). Nat. size.
Sclerophytum polydactylum (Ehrenberg). Nat. size.
Dendronephthya (Spongodes) brevirama (Burckhardt). Nat. size.
Virgularia rumphii, Kolliker. Nat. size.
Virgularia rumphii, Kolliker. ‘Dorsal or metarachidial surface showing the curious inter-
linking of the pinnules. x 5.
LEchinomuricea wliginosa, Thomson and Simpson, var. tenerior nov. xX 1°5.
Echinomuricea uliginosa, Thomson and Simpson, var. tenerior nov. x 10.
Lophogorgia lutkeni, Wright and Studer. Nat. size.
Virgularia rumphii, Kolliker. Ventral or prorachidial surface with a bare streak.
Echinomuricea uliginosa, Thomson and Simpson, var. tenerior nov. Spicules.
Juncella juncea (Pallas). x 1°5.
+ ee See 2
ALCYONARIANS PLATE.
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REPORT
ON THE
NUDIBRANCHS
COLLECTED BY MR. JAMES HORNELL
AT
OKHAMANDAL IN KATTIAWAR IN 1905-6,
BY
SIR CHARLES ELIOT,
Vice-Chancellor of the Sheffield University,
WITH A NOTE ON THE PRESENCE OF SYMBIOTIC ALGA IN
MELIBE RANGIT, BY J. HORNELL.
[Text-Figures. ]
The collection of Nudibranchs from the coast of Kattiawar sent me for
examination by Mr. Hornell contains seven species, which I identify as follows :—
(1) Chromodoris petechialis (Gould).
(2) Plocamopherus ceylonicus (Kelaart).
(3) Bornella digitata, Adams and Reeve.
(4) Melibe rangi, Bergh. Probably = M. fimbriata, Alder and Hancock.
(5) Antiopella indica, sp. nov.
(6) Ptereolidia semperi, Bergh.
(7) Elysia grandifolia, Kelaart.
With these are also some specimens of a small Plewrobranchus and of an
Oncidium.
The collection, though small, has not been easy to identify. The specimens of
known species present variations sufficient to throw doubts on the identifications
137
138 OKHAMANDAL MARINE ZOOLOGY REPORT
proposed, and the new species of Antiopella is so near to A. novozealangica that the
question naturally arises if it is more than a variety. The obvious inference is that this
corner of the Indian Ocean is developing varieties which are in a fair way to fix
themselves as species. To the best of my belief the only other nudibranchs recorded
from this coast are comprised in a collection made by Mr. W. Townsend partly at
Karachi and partly at Maskat and on the coast of southern Persia. They were
described by me in the Journal of Conchology for 1905, pp. 237-256. The species
recorded from Karachi are *Bornella digitata, Thecacera maculata, Goniodoris
modesta (2), Chromodoris semperi, *Chr. petechialis, Doriopsilla miniata, Doridopsis
rubra. The two species marked with an asterisk are represented in the present
collection.
Chromodoris petechialis (Gould).
Gould, U.S. Exploring Exped. 1838-42, vol. 12, p. 296; Atlas, figs. 391, 391 4a; Eliot, Nudibranchs
from the Pacific, in Proc. Malac. Soc. 1904, pp. 231-2; Eliot, Notes on a Collection of Nudibranchs
dredged near Karachi and Maskat, in Jour. of Conchol., 1905, pp. 250-1.
Two specimens of much the same size and appearance. They are about 26 mm.
long, 22 mm. broad, and 12 mm. high, stout, broad and soft. At first sight the colour
appears to be a uniform flesh tint without markings. On a closer examination, the
mantle margins and portions of the dorsal surface are seen to be more opaque than the
rest, and it is probable that in life there were spots on the back and a coloured border.
The foot is grooved in front, but not notched, and there is a short, stout tentacle on
either side of the mouth. The branchize are deeply retracted into the pocket, which is
closed in both specimens : they are 12, simply pinnate, and yellowish.
The intestines are of a deep reddish purple, but the yellowish hermaphrodite gland
(which is very small) forms a dendritic pattern contrasting strongly with the dark
mass of the liver. The labial armature is purplish and forms a nearly complete ring,
which, however, is interrupted at one point. The elements of it are minute bent rods
which bear an accessory denticle near the tip and hence generally appear to have
irregularly cleft ends. The formula of the radula is about 90x 85.0.85. The first
tooth is broad, with a shoulder projecting into the rhachis, and denticulate on both
sides. The second tooth is also broad and denticulate on the outer side only. The
remaining teeth are erect and bear 7-10 denticles on the outer side. Those at the end
of the row are rather taller than is usual in the genus and bear 4-5 denticles on the
apex.
I think these animals are the same as the specimens from Karachi described by
me in the paper referred to above as Chromodoris petechialis. They are, however,
twice as large and therefore have larger radule. It is impossible to say whether the
spots and borders have faded or whether they were faint in the living animals. In
the latter case, the specimens probably are the Chromodoris picta of Pease from the
ELIOT—NUDIBRANCHS 139
Sandwich Islands (Pease in Proc. Zool. Soc. 1860, page 29), which will thus be a pale
variety of Chr. petechialis. .
Plocamopherus ceylonicus (Kelaart).
Alder and Hancock, On a Collection of Indian Nudibranchiate Mollusca, 1864, pp. 132-4. For
Pl. imperialis, see Bergh in Verhandl. der k.k. zoolog. botanischen Gresellschaft in Wien, 1883, pp. 12-17,
and for Pl. ocellatus, Eliot in Linn. Soc. Journ. Zool., vol. 31, November, 1908. Ey
Five specimens from Kiu. Their delicate and gelatinous consistency has serneedl
all of them to be much contracted and distorted in the preserved condition, and it
is difficult to give any satisfactory description of the external characters. The general
shape was probably as in Alder and Hancock’s figures of Plocamopherus ceylonicus :
the oral veil very large, the branchial tuft large and central; the dorsal ridge on
the tail only moderately developed, but distinct.
As preserved the specimens vary from 15mm. to 35mm. in length. The
coloration also is variable and in many cases the epidermis has been rubbed off.
As a rule the ground is transparent and colourless or faint yellow, but is covered in
most parts by irregular mottlings of a beautiful brown of varying shade and intensity.
They are deepest in colour and most regular in arrangement on the back. Among
these mottlings are fairly numerous white or cream-coloured areas, distinct but
irregular in outline. They are either plain or contain numerous small dots. The
club-shaped tips of the dorsal processes are of a dull plum colour.
The large oral veil bears numerous processes (as many as thirty in large
specimens), which are pinnate or sometimes hipinnate, but as preserved quite small,
rarely attaining a millimetre in length. In all the specimens the head parts are
much contracted and it is impossible to say anything about the tentacles or the
pedal groove. There are three fairly large processes on either side of the back,
much contracted, but evidently bearing several branches. They bear as a rule at the
end a single round knob, which in all the specimens is of a dull plum colour and
contrasts with the rest of the integuments. In three specimens all the processes
have this knob: in one it is absent in the right anterior process, and in another
both the anterior processes are ramified, but without a knob. This is the condition
described by Alder and Hancock as found in Pl. ceylonicus. There are a few
other smaller processes scattered over the back and sides. They are more
numerous in one specimen than in the others. There are traces.of processes on
the caudal ridge. The branchie are large and strong, mottled like the back,
and five in number. The rhinophores are whitish and retractile into cavities with
papillate margins.
The labial plates are yellow or brown and triangular. The radula varies in
colour from light yellow to dark brown. The rhachis is very broad and traversed
by cross-lines. There are from fifteen to eighteen rows of teeth. The anterior rows
140 OKHAMANDAL MARINE ZOOLOGY REPORT
are incomplete and have a formula of about 7+3. 0. 3+7. In the hinder rows
the number of teeth increases considerably and in the three specimens examined
attained a maximum of 11+3. 0. 3+11, 12+3. 0. 3412, and 154+3. 0. 3415
respectively. The three innermost teeth are large and hamate, but the base of the
first tooth does not project markedly into the rhachis as in some species. The fourth
tooth bears a projection not amounting to a hook and there are traces of smaller
prominences on the fifth and sixth. The outer teeth are flat plates.
The other internal organs are much as described by me for Pl. ocellatus (I.c.), but
the cesophagus on issuing from the buccal mass begins to dilate almost immediately
into a long stomach-like pouch, which varies in shape in the different specimens, and
is constricted just before it enters the liver. The genitalia are small and appear to be
immature or at least not functionally active. The dendritic prostate characteristic
of the genus is present, but smaller than in the specimens of Pl. ocellatus which I have
examined. ‘
I think these specimens are probably a variety of Pl. ceylonicus. They agree
with Alder and Hancock’s description in most points, but still present differences of
some importance. (1) The skin is much smoother and not covered with so many
papillz and processes. But such projections often disappear when a soft animal
shrinks and contracts in the preserving fluid. (2) The radula is rather broader; but
it is probably variable, and Alder and Hancock do not indicate that they examined
more than one specimen. (3) The plum-coloured knobs are not mentioned in their
description and must be a peculiarity of this variety. Except for the colour, the dorsal
processes in one specimen correspond exactly with Alder and Hancock’s account.
Since Pl. iumperialis, Angas, has purple knobs on the dorsal processes (but only on
one pair) it would be natural to refer these specimens to it, but they seem to differ from
it in some points more decisively than from Pl. ceylonicus. (1) Pl. umperialis is said
to have two dorsal ridges which meet in a point behind. The present specimens show
no trace of such a ridge. (2) Pl. imperialis has 5-7 hamate teeth, but in the present
specimens the number of hamate teeth is consistently three only. But I should not be
surprised to find that Pl. ceylonicus and Pl. imperialis pass into one another by gradual
modifications.
Pl. ocellatus from the Red Sea offers few points of structural difference from
Pl. ceylonicus, but superficially the present specimens do not resemble those sent me
by Mr. Crossland.
Bornella digitata, Adams and Reeve.
Eliot, Proc. Zool. Soc. 1904, vol. 2, pp. 100-2, and references there quoted ; and id. in Journ.
of Conchol. 1905, p. 238.
One specimen from Chindi reef. As preserved, it is colourless, somewhat bent, but
about 35mm. long if straightened out, and stoutly built. The rhinophore sheaths
bear three short processes in front and a long one behind. Besides the rhinophore
ELIOT=+NUDIBRANCHS 141
sheaths there are six pairs of cerata: the first pair are trifid; the second, third, and
fourth are bifid ; the fifth and sixth are simple.
The specimen is of the same type as those from Karachi described by me in the
Journal of Conchology (l.c.). The species is probably common in these waters.
Melibe rangii, Bergh. Probably=M. fimbriata, A. and H.
See Bergh, Malacol. Untersuch. ix. 1888, pp. 370-6, and Alder and Hancock, Notes on a Collection
of Indian Nudibranchiate Mollusca, 1864, pp. 137-9.
Seven specimens from Kiu, Okha. The largest is about 80 mm. long, but
as it is bent this represents a real length of at least 100mm. The general
colour is a very faint transparent hyaline green, which allows the pink and white
viscera to be seen clearly. The muscles are also clearly visible as a network
of intersecting stripes. In places there are brownish spots and all the processes,
filaments, cirrhi of the hood, &c., tend to be olive green, especially on the upper
parts of the animal.
The back bears from six to eight pairs of large cerata.'. In the best preserved
specimen, which is only 55 mm. long, they are 21 mm. high. In some cases, however,
they are quite small, even near the middle of the back. This is apparently due
to the full-grown cerata having fallen off and been replaced by fresh growths.
Most of the cerata in the present collection are detached and show a configuration
like that depicted by Bergh for Melibe vexillifera (Bergh, Verh. d. k.k. zool. bot.
Ges. in Wien, 1880-1, Pl. II. fig. 3), namely, a globular tuberculate base bearing
a thinner crest with jagged membranous edges. But in the specimen where the
cerata remain im situ they are tall and wedge-like, and this is probably the natural
shape, the other being due to distortion caused by the contraction of the base.
Besides cerata there are on the surface of the body : (1) small low tubercles, simple
or compound, especially numerous on the sides and on the hood ; (2) largish pointed
papillee ; (3) simply ramified processes, as much as 12mm. high, especially numerous
on the back. The rhinophore sheaths are tall, slender, and provided with one or
more long digitate processes. The club of the rhinophores is small; opaque white
or yellowish. The opening of the hood is circular and bears inside three or four
irregular rows of long (as much as 14mm.) snaky cirrhi. The lips are not raised
and the mouth is merely a roundish opening surrounded by very small papille.
The mouth opens into a tube more or less coloured with dark pigment. In
its walls are embedded two small jaws, yellowish, membranous, and irregularly den-
ticulate. A short laminated cesophagus leads directly into the stomach, which is
surrounded by a very distinct girdle of about forty plates. They vary considerably
in colour (red, yellow, or grey) and in size, but do not alternate regularly. Behind
1 For details respecting the appearance of these cerata when fresh, see Mr. Hornell’s note and
figures, pp. 145-7 below.
142 OKHAMANDAL MARINE ZOOLOGY REPORT
the girdle comes a constriction, and the posterior part of the stomach is soft and
laminated. From it issues the large intestine, which is laminated internally and
provided with a ridge. It runs straight to the anus, which is situated just in
front of the second of the cerata on the right side. At the point where the intestine
issues from the stomach is a diverticulum with puckered walls. The liver is a
mass of small tubes, white or yellowish, which completely surround the herm-
aphrodite gland. It consists of three portions: a very small. one on the right
of the’ stomach and a rather larger one on the left uniting with the posterior
portion, which is much the largest of the three. The livers send up prolongations
which enter the dorsal integuments and reach the base of the cerata, but I could
not discover either by external examination or by sections any trace of hepatic
diverticula within the cerata. .
The hermaphrodite gland, which is entirely surrounded by the liver tubules,
consists of a great number of globules. Its duct is long and leads into a long ampulla
bent upon itself several times. After the bifurcation, the female branch becomes
broad, flat and puckered, forming a complete loop (the ‘‘Schlinge” in Bergh’s
description of Melibe rangii). It then contracts again. The spermatotheca is
elongated and has a short broad duct. The male branch passes almost immediately into
the large spherical prostate, which consists of two portions, the smaller yellow or
greenish and the larger pink. From this pink portion issues the thin but muscular
vas deferens, which forms two coils and then passes into the penis. This organ is
long, dagger-shaped, and either straight or bent. In most of the specimens examined
the genitalia were small, but in one the mucus and albumen glands were swollen to
an enormous size, and distended the interior part of the body. The pink prostate is
a conspicuous object even externally, as it can he seen through the integuments. In
the central nervous system the ganglia are strongly granulated and not distinctly
divided from one another.
These specimens seem referable to Melibe rangii, Bergh, but this species (1888)
is probably the same as the earlier M. fimbriata of Alder and Hancock, 1864. There
are some external differences, and A. and H. state that their species has no jaws,
but I have shown (in Jour. of Conchol., vol. 12, No. 3, July, 1907, pp. 90-1) that
this statement is probably an error. But as there can be little doubt that these
specimens are M. rangii, I use that name until the identity with M. fimbriata can
be established.
The only feature which militates against the identification of these specimens with
M. rangii is that they have no trace of hepatic diverticula within the cerata, although
the liver extends to the base of the cerata. It is probable that different individuals
show diversity in this respect, as in Dendronotus and Bornella.
From an examination of the living animals, Mr. Hornell was led to think that
symbiotic alge might be present in the small ramified processes borne by the cerata,
ELIOT—NUDIBRANCHS : 143
and in other brownish portions of the integuments. The integuments, as preserved,
do not in any way discountenance this supposition, but in their present condition they
do not afford good material for histological examination. Mr. Hornell’s notes and
drawings are therefore appended without addition.
In the Quarterly Journal of Microscopical Science (March, 1908, pp. 287-8), Mr.
Evans and myself indicated the possible presence of symbiotic alge in the dorsal
regions of Doridoeides Gardineri.
Antiopella indica, sp. nov.
For the synonymy Antiopella=Janus= Antiopa, see Eliot, Notes on some British Nudibranchs,
Journ. Mar. Biol. Assoc. 1906, p. 373.
Two specimens marked Kiu, Okha. They are solidly ‘built with flat backs. The
measurements of the larger are: length 11 mm.; breadth across the rhinophores, which
is the widest part, 6°5mm.; height 5°5 mm.
The integuments are transparent, but the general coloration is somewhat
mottled because the pinkish, whitish, and greenish intestines show through the back,
foot, and sides. Also on the back, lips, rhinophores and crest, anal papilla and
sides are scattered quite irregularly small reddish-brown spots. The cerata are
greenish-grey and the parts of the back near them seem to be marked with faint
light stripes running towards the margin.
The cerata are arranged along the margin of the back, at most two or three
deep. They are small (largest 1°5mm. high), thin, and not like those of most
Janide. They extend in front of the rhinophores. These latter, as well as the
crest between them, are well developed and thickly perfoliate. The anal papilla is
very large: it is set far back in the medio-dorsal line. The genital orifices are
about 35mm. from the head and not conspicuous. The oral tentacles are
indistinct. The foot is moderately broad.
The buccal mass is large. The jaws are red and bear a single series of very
large denticles. The tissues around them are pinkish-white. The formula of the
radula is 21x31. 1. 31 as a maximum, but the front rows are only 12. 1. 12, the
number of teeth increasing rapidly in the hinder rows. The teeth are thin, trans-
parent, and colourless, of the hamate type usual in the genus and not denticulate.
They are somewhat crowded, but the rhachis is wide and the median teeth plain.
The stomach and the liver tubes which communicate with it are very thin and not
at all muscular. A hepatic duct enters the stomach on either side and a third
behind. These ducts give off branches which enter the integuments and form a
spongy layer under the cerata.
The anterior genital mass is pinkish and of small size. The spermatotheca,
however, is large, elongated, and in the specimen examined empty. The hermaphro-
144 OKHAMANDAL MARINE ZOOLOGY REPORT
dite gland is in two divisions which are united below the posterior parts of the
alimentary organs, but rise up above them on either side. It consists of large,
clear, pinkish packets of follicles. The central nervous system is much as in
Bergh’s figures of Janolus australis (Challenger Report, 1884, Pl. IX. fig. vi.).
The eyes are stalked.
In many ways this animal resembles A. novozealandica and the two may even
be varieties of one species. But as preserved they are not very similar in appearance ;
the colour is not the same and the cerata and rhinophores are smaller in this species.
Pterceolidia semperi, Bergh.
See Bergh, Beitr. zur Kennt. der Aeolidiaden, iii. p. 22, and Malac. Untersuch. i. p. 18 (1870), under
Flabellina ; Eliot, Proc. Zool. Soc. 1903, pp. 255-6.
Five specimens from Kiu, Okhamandal. They are coiled up, but are about
40-50 mm. long. The colour as preserved has become a transparent yellowish-white,
but traces of red and green can be seen. The shape is slender and elegant. There are
from fifteen to twenty groups of cerata which are not at all caducous. The anterior
angles of the foot are produced and deeply grooved. The oral tentacles are large ;
the rhinophores small, stout, and lamellated. The dorsal margin is not marked by a
ridge.
In the specimen dissected the radula consists of a single row of eighteen teeth,
bearing eight denticles on either side of the central cusp. The cutting edge of the
jaws is armed with many rows of denticles.
Ptereolidia semperi is recorded from the Philippines, Zanzibar, and Japan, and
is probably generally distributed in the Indo-Pacific. It is a beautiful creature when
alive, with a complicated coloration which produces a general effect of purple with a
greenish silvery glaze.
Elysia grandifolia, Kelaart.
Kelaart, Ann. and Mag. Nat. Hist. 1859, vol. ili. p. 493; Eliot, Proc. Zool. Soc. June, 1906, p. 689,
Seven specimens from Kiu. The largest are about 30mm. long and 20mm.
broad. The colour is somewhat variable, but the best preserved specimens indicate
that it was olive green, with a very distinct border to the wings and rhinophores which
is now white but shows signs of having been yellow. This border is accompanied on
the outside by a second thinner line of black, very distinct where it occurs, but often
interrupted and in one specimen entirely absent. The head is large, the tail long and
pointed. The pericardial prominence is of varying shape, but generally elongate. The
radula of the specimen examined had eight teeth in the ascending series, twelve in the
descending, and about thirty in the heap of various sizes, The lower edge of the teeth
HORNELL—THE PRESENCE OF SYMBIOTIC ALG IN MELIBE 145
is very minutely serrulate. The ramifications of the liver extend to the extreme edges
of the wings and tip of the tail and are very distinctly visible from the outside.
As pointed out in my paper referred to above, there is much confusion in the
nomenclature of the tropical Elysiide, but Kelaart’s names appear to be the earliest
and grandifolia should be kept as the specific designation of a large species with a
pointed tail and typically of a green colour with two borders, yellow and black, which,
however, are not developed in all specimens.
A NOTE ON THE PRESENCE OF SYMBIOTIC ALG
IN THE INTEGUMENTS OF NUDIBRANCHS OF THE GENUS MELIBE,
By JAMES HORNELL.
During the Ceylon pearl fishery of 1905, when making my daily visit of
inspection to the boats at work, it was my habit occasionally to board one or
more to note the progress and conduct of the diving operations. One day in
February when aboard a boat fishing on the South Moderagam Par in six
fathoms, my eyes fell upon a handful of flaccid brown masses in a diver’s net just
drawn up. My first thought was that they pertained to some species of Aplysia,
several of which are extremely abundant at times on the pearl banks: I was about
to pass them as of no importance when a something unfamiliar in their appearance
caused me to reach forward to take possession. But a diver a second before [
could pick them up flung the greater part back into the sea and I had but four
left.
These I examined on return to my quarters, and then found them of greater
interest than I had imagined. The four masses were practically identical in form,
colouring, and size; none showed any trace of alimentary canal or of any orifice
whatever, but each showed a disc-shaped place of attachment, 5 mm. in diameter,
on one surface. Each mass was laterally compressed, stout and fairly thick towards
the disc of attachment, thence narrowing gradually to a thin crest-like ridge upon
the upper margin, and in general form closely resembling the crested pneumatophor
of Physalia. In vertical transverse section it was distinctly pyriform in outline.
The ground coloration was of two shades of brown, irregularly distributed, and
flecked here and there with small irregular patches of grey.
When I handled the masses first, the surfaces were covered with closely-set,
low wart-like papille irregularly distributed, at some places more or less aggregated
in fairly densely-set groups, at others rather widely separated from one another.
After immersion in water for some minutes, the appearance underwent a considerable
146 OKHAMANDAL- MARINE ZOOLOGY REPORT
change; each mass plumped out and each of the wart-like papillee became the
base of a tiny arborescent tuft of branching threads. The general substance possessed
a certain amount of contractility when irritated, shrinking away when touched,
while the arborescent tufts suffered complete retraction at the place affected. The
tufts did not again expand fully for quite a minute after the cause of irritation
ceased.
Examination under the microscope resolved each arborescent tuft into a group
of digitate papille having perfectly colourless transparent walls, so tenuous as not
to be visible to the unaided eye. In each digitation was a branched or dendritic
tuft made up of brown cell-rows having a very close resemblance to the branching
threads of certain filamentous alge. It was the massing of these branched threads
that gave the arborescent appearance to each of the tufts referred to above
(Figs. 1 and 2).
The cells of these branched strands were of uniform diameter, and each had
a well-defined nucleus. Besides forming the threads within the digitate papille
these cells were also found in masses spread over the general surface of the organism
and forming brown patches here and there according to the relative abundance
of the cells. Other patches of brown, but deeper in tint and with a shade of red
in it, formed the remainder of the brown coloration of the surface, and wherever
such reddish-brown patches were, a great abundance of very minute red-brown
cells was indicated, the cells aggregated into rows (Fig. 8) or into irregular masses
(Fig. 9). Few or none of these minute brown bodies were met with in the digitate
papillee. .
The surface patches coloured grey were seen under the microscope to be composed
of granular cell-tissue, apparently colourless (Figs. 5 and 6). In each cell was
a clear spherical nucleus. The cells were irregular in outline, varying considerably,
but agreed usually in being elongated along one axis, so that they often formed
strand-like tracts. This grey tissue had a superficial resemblance to squamous or
tabular epithelium. It appeared to be restricted to the surface, but here and there
at some distance from the surface were small centres of a pale yellowish tissue made
up of cells, which, if not identical, appeared to be closely related ; indeed, the only
perceptible difference was that these more deeply seated cells were irregularly stellate
in outline (Fig. 7).
The mass of the organism was distinctly areolar, large rounded cavities occupying
the greater part of the interior, separated more or less by a network of fine colourless
strands which appeared to be muscular. These colourless fibres were specially distinct
within the digitate papilla. On some of the threads protoplasmic centres could
be seen, each with a nucleus. A few gland-like bodies were observed in the digitate
papille, containing secretion matter in the lumen. One was noticed to open by
a well-marked orifice upon the surface. Associated with the brown cellular strands,
HORNELL—THE PRESENCE OF SYMBIOTIC ALGA IN MELIBE 147
apparently algal, were quantities of clear, rounded, colourless cells filled with
refractive granules (Figs. 4 and 4a).
The above notes were made during a rough examination of the living tissue.
As I was greatly pressed for time, they are necessarily superficial ; time and opportunity
to carry the inquiry further have both been lacking.
For some time I was unable to satisfy myself as to the nature of the organism.
As the handful of its separate masses was all in one diver’s bag, I inferred that
they had been grouped together when torn from their attachment by the diver, their
sessile manner of growth being shown by the small discous scar which each bore.
The apparently symbiotic conjunction of animal and plant (algal) tissues puzzled me,
as did the lack of any indication of alimentary or other canal. Later, I was able to
identify the masses as cerata from the dorsum of a large Nudibranch of the genus
Melibe, the M. rangu of Bergh.
148 OKHAMANDAL MARINE ZOOLOGY REPORT
EXPLANATION OF TEXT FIGURES ON PRECEDING PAGE.
Fig. 1. Group of digitate papille, as seen under a hand lens.
The walls of the papillae are extremely delicate and perfectly transparent,
and are not visible to the naked eye, which sees only the branching strands of
brown alge. To the unaided vision a group of these papillae appears as a much
branched, brown arborescent tuft (Fig. 1¢).
Fig. 2. Distal portion of a papilla more highly magnified, showing gland-like
bodies and a branching algal strand.
The -fine lines would appear to represent muscular fibres penetrating the
papilla.
Fig. 3. A double row of algal cells from a papilla yellowish-brown in life.
Fig. 4. Colourless cells with clear refractive granules within.
Fig. 4a. A group of the same found associated with the algal threads.
Figs. 5 and 5a. Groups of cells from grey patches on the surface of the
main mass of the organism. Under the microscope this grey matter is seen to
consist of irregularly shaped cells, not unlike squamous epithelium—contents granular
and apparently colourless. A clear nucleus in each.
Fig. 6. Two isolated cells of same, showing characteristic elongated form.
Fig. 7. Two irregularly stellate cells from slightly yellowish tissue from a
little way below the surface; the granular contents and clear nuclear centres are
similar in appearance to those of cells from the grey surface tissue
Fig. 8. Strings of very minute cells, dark brown in colour, with a tinge of
red. Found mostly in the surface layer’ of the mass.
Fig. 9. Irregular mass of the same cells as depicted in Fig. 8.
Figs. 2—9 drawn under ¢ in. Beck obj.
RICHARD CLAY AND SONS, LIMITED, BREAD STREET HILL, E.C., AND BUNGAY, SUFFOLK.
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