i el Natural History Museum Library | CL DAYS AND HOURS OF ADMISSION. The Exhibition Galleries are open to the Public, free, every week- day in January, from 10 a.m. till 4 P.M. February, Oi sa aan a5 Geen Oe March, itn: line ey so oO Fu April to August, pe ia) raed oro nts September, » » 9» 9 980 ,, October, Saar aa ite EL vat November and December Heh tne ae Wore a "nae Mie Also, from May Ist to the middle of July, on Mondays anda Saturdays only, till 8 P.m., aay and from the middle of July to the ni of August, on Meat) and Saturdays only, till 7 P.M. The Museum is also open on Sunday afternoons throughout the year. The Museum is closed on Good-Friday and Christmas-Day. By Order of the Trustees, ; E. RAY LANKESTER, — | Director. GUIDE TO THE GALLERY OF FISHES IN THE DEPARTMENT OF ZOOLOGY OF THE BRITISH MUSEUM (NATURAL HISTORY), CROMWELL ROAD, LONDON, 8.w. ILLUSTRATED BY 96 FIGURES. LONDON : PRINTED BY ORDER OF THE TRUSTEES OF THE BRITISH MUSEUM, 1908. Price One Shilling. fio FipMASUtceat pox Wi ye Preece at a a ee Gtr It DE TO THE GALLERY OF FISHES IN THE DEPARTMENT OF ZOOLOGY OF THE YK BRITISH MUSEUM (NATURAL HISTORY), CROMWELL ROAD, LONDON, 8.W. ~ f Oef>*, f 7 we. [W. G. Fira eCwered. | ig 7 ay ILLUSTRATED BY 96 FIGURES. LONDON : PRINTED BY ORDER OF THE TRUSTEES OF THE BRITISH MUSEUM. 1908. All riyhts reserved. a U2LI5I3 PRINTED BY TAYLOR AND FRANCIS. RED LION COURT, FLEET STRELY, PREFACE. THE arrangement of the Fish Gallery and the preparation of the coloured skins and casts which are there displayed, have occupied a good deal of my time for the last four years. The work of mounting and labelling have been done under my supervision by Dr. Ridewood; the preparation of coloured skins and casts by the taxidermists and modellers.employed for the purpose. If large series of fishes are to be exhibited to the public, it seems to be necessary that they should be carefully painted over so as to give, as far as possible, the natural colours of fresh specimens. This is an extremely difficult task and I have no doubt that, in spite of the care which has been taken, correction and revision will be needful hereafter, in regard to some of the specimens. Many of the specimens have been coloured from life and the rest from authoritative coloured drawings either published or communicated for the purpose. The models of Deep-sea Fishes and of several extinct fishes have been most carefully executed under my constant supervision and are entirely new. The series of the species of living Dipneusta (Prtoopterus and Lepidosiren) are ad- mirable representations of those fishes. The specimens of the Tunny, of the Flying Gurnards, and of the brilliantly iV PREFACE. coloured Plectognaths, Angel-fish, and similar forms seem to justify the method of coloration employed. The principle had already been accepted by the late Keeper of Zoology, ‘Dr. Giinther, who had prepared several specimens coloured in this way. JI believe that there is no other collection of Fishes in a public museum in which the specimens are presented without the usual iron supports, with sufficient space around each fish and in natural colours, instead of the oily brown which all dried fish skins tend to acquire. The attitude of the specimens in the Gallery is ether that of a dead specimen lying on a slab, or is a conventional one chosen so as to shew as much of the character of the fins as possible. It would not be possible to faithfully present the fish in the act of swimming, nor would fish in their natural surroundings be a desirable kind of exhibit: for, like many other animals, fish in their native haunts are usually concealed by their colour and surroundings from the cbserver’s eye. The present Guide has been prepared by Dr. Ridewood in daily consultation with me. Several of the illustrations are new: for others we are indebted to Guides formerly published by the Trustees, and to Messrs. Macmillan and Messrs. A. and C. Black. Every specimen in the Gallery is provided with a number and is referred to in this Guide by that number printed in thick large type. Tne English names or common names of specially inter- esting fishes are affixed in large letters to the glass of the case ina position near the specimens of such fishes. All those fishes which come under the head of British Food-fishes are indicated in the case by the letters B. F. F. The label of each specimen gives its zoological name, its local name, its English name or names, and as far as practicable its French, German and Italian names. The distribution of PREFACE. Vi the species is stated and the particular locality from which the specimen exhibited was obtained. In addition information is given as to any matters of special interest concerning the fish. This Guide is a collection of the labels with some additions, arranged systematically so as to shew the groups into which fishes are divided, and is illustrated by figures which are to a large extent taken from photographs of the specimens actually seen in the cases. K. RAY LANKESTER, Director. British Museum (Natural History), London, S.W. Dec. 23, 1907. ADDENDUM. Since the above preface was written, it has been thought desirable not to use the “ thick large type” for the numerals denoting the individual specimens, and these have therefore been printed in ordinary type. ira (a iar Pai) '* 7 . ae a vey Pig » Hol | is’ * “~ M whi toh ' ay rei Ly by ne oe. 0 Piolo GALLERY, INTRODUCTION. Tue Fish Gallery is on the main floor of the Museum, in the western portion. Visitors entermg the Museum can reach the Fish Gallery by turning sharply to the left into the Bird Gallery, and taking the first turning to the right ; or by passing through the Entrance Hall along the left side, and, on reaching the archway at the left side of the main staircase, turning to the left through a ‘small doorway. The specimens exhibited in the Fish Gallery consist mainly of stuffed specimens, coloured as far as possible to resemble the fishes in their natural conditions ; there are also some casts and models of fishes, the skins of which are not suitable for exhibition, either because of their damaged or distorted condition, or because of their small size, or because the skin is so thin that it cannot be stuffed, or because the fishes are extinct, and only fossil fragments remain to indicate to us what they must have looked like. Only a small proportion of the Fishes in the Museum are exhibited in the Fish Gallery ; the greater number are preserved in alcohol and, as a precaution against fire, are stored in a detached building at the back of the Museum. These specimens are mostly unsuited for exhibition, and are not accessible to the general public ; they are, however, available for scientific purposes by ichthyologists under certain conditions, which can be ascertained by making application in writing to the Museum. A large B Exhibited specimens, Specimens for Study. Table- case 21. 2 FISH GALLERY. collection of skeletons of Fishes is similarly available for purposes of scientific study. On entering the Fish Gailery from the Bird Gallery the visitor will see two small Table-cases (21 and 22) standing in the middle line of the Gallery, the first containing specimens and enlarged models of the Lancelet, and the second containing Lampreys and Hag-fishes. These are not ‘ Fishes” in the strict use of the word. The Lancelet is not even a vertebrate animal, in the sense in which that term is now employed, but belongs to the Cephalochorda, a division of the Chordata ranking equal with the Urochorda or Tunicates (Sea-squirts, Salps, &c., exhibited in the Shell Gallery), and the Vertebrata (including Lampreys, Fishes, Amphibians, Reptiles, Birds and Mammals). The Lancelet resembles the Tunicates and the Vertebrates in having a median skeletal rod, known as the notochord, in the dorsal position and tubular character of the central nervous system, and in the perforation of the side wall of the body in the neck region by gill-slits. The Lancelet differs from the Tunicates and Vertebrates in that the notochord extends farther forward than the central nervous system. CEPHALOCHORDA (Lancelet). The Lancelet or Amphioxus (fig. 1) is a small, semitrans- parent, marine animal about two inches in length (see specimens in alcohol, 1046, Table-case 21) ; it lives in shallow seas in many parts of the world and frequently buries itself in the sand. The edge of the mouth is produced into a number of curved bars or “buccal cirri” (see enlarged model, 1047), which act as strainers and prevent sand grams from getting ito the mouth, while not stopping the water that is used for respiratory purposes, nor the minute living organisms that constitute the food of the Lancelet. The gill-slits do not open directly on to the exterior of the body, but are covered in by a wall called the atrial wall, which extends as far back as the pore (atriopore), through which issues the water that has passed through the gill-slits. The anus or vent is unsymmetrical, being set on the left side of the lower fin; there is no distinct head, no paired fins, and no paired eyes or ears. LANCELET. 3 For the general internal structure of the Lancelet the visitor is referred to the special case affixed to the side of one of the arches on the West side of the Entrance Hall of the Museum. The two specimens A and B, 1048, mounted on the framed pane of glass in Table-case 21 are wax models, enlarged 100 diameters, showing the remarkable lack of symmetry that exists during the early or larval stages of the Lancelet. The mouth developes on the left side, and only subsequently passes downward to occupy a median position. Primary gill-slits, to the number of fourteen, appear in the ventral median line and move upwards on the right side. Hight secondary gill-slits then appear above them on the right side, and, as they enlarge, the primary gill-slits descend and pass across to occupy their permanent position on the left side. After this, tertiary gill-slits develope on both sides behind the existing ones and continue to increase in number throughout life. The Fie. 1.—Lancelet: a, mouth; b, atriopore; c, vent or anus ; d, anterior end of notochord. three nrodels 1049 C, D, and E on the other framed glass show the manner in which the atrial wall, which in the adult covers over the gills, closes by the downward and horizontal extension of the side folds of the body (metapleural folds), and the union of the edges of these flaps along the middle. The models represent three different stages of development, and show the ventral or under surface of the larva. In C there is no atrial floor, the right and left metapleural folds being distinct; in D the horizontal ledges growing in from the inner faces of the metapleural folds have united in the hinder part ; in E the whole of the atrial floor is complete except at the extreme anterior end. On the other side of the Table-case are shown enlarged models of Tunicates for comparison with the Lancelet, one (1050) of the larva of a simple Ascidian such as the common Sea-squirt, and three models (1051, 1052, 1053) showing different views of an B2 Table- case 22. Lamprey. 4 FISH GALLERY. adult Appendicularia (Fretillaria furcata), which is one of the few Tunicates that retain the tail in adult life. At the end of the case are shown drawings of ten species of the Lancelet. CYCLOSTOMI (Lampreys and Hag-fishes). The Cyclostomi, or Lampreys and Hag-fishes, are aquatic: Vertebrates not included among the “ Fishes” or Pisces because of the absence of a hinged lower jaw. The mouth is adapted for sucking; when open it is round in shape (whence the name Cyclostomi, or “round-mouth”), and it is closed by the approximation of the right and left margins; the teeth are of a horny material and have a vertical succession. The body is long, without scales in the skin ; the tail-fin is simple, and there are no paired fins and no traces of pectoral and pelvic girdles. The nostril is single; the gills are in pouches, the external and internal openings of which are small. The skeleton is fibro-cartilaginous, and the notochord persists for life. Two divisions of the Cyclostomi are recognised, the Hyperoartia (Lampreys) and the Hyperotreta (Hag-fishes). In the Hyperoartia the external nasal aperture is on the upper surface of the head, and from the inner end of the nasal sac there leads back a tube which ends blindly above the pharynx (see dissection 1059). There are no barbels. The eggs are small. (see 1060). Hach gill-pouch has its own externa] aperture. The median fins are relatively larger, and are more subdivided than in the Hyperotreta. Various species of the Lamprey occur in the temperate parts of the northern hemisphere, the commonest being the Lamprey, Petromyzon marimus,. 1057, and the Lampern or River Lamprey, Petromyzon fluviatilis, 1058. The word Lamprey comes to us from the Low Latin name lampreda or lampetra, the licker or sucker of rocks, applied to the animal on account of its peculiar habit of adhering by its mouth to stones. ‘The generic name Petromyzon applied by scientists refers also to this habit. The mouth when open (1062) forms a sucking disc, with numerous brown, horny teeth arranged in circular and radiating rows, and with. some in the centre LAMPREYS. 5 supported by the tongue. The circular lip around this sucking dise 1s fringed with numerous short tentacles. The Lamprey does not “bite” its food as an animal with ordinary jaws would do, but attaches itself by its disc to the skin of living Cod, Haddock, and Mackerel, and gnaws away the flesh by its pointed conical teeth, until it has satisfied its hunger, when it leaves the fish to recover, or more probably to die. The Lamprey has two dorsal fins, the second being continuous with the caudal; the skin is slimy, the eyes are very small and situated in front of the seven small, circular gill-openings. The skull of the Lamprey affords but little protection to the upper part of the brain, the roof ‘consisting merely of a narrow “occipital arch” (see 1061). The ‘‘subocular arch” possibly corresponds with the palato-quadrate cartilage of the true Fishes, the cartilage which in Sharks and Lung-fishes functions as the upper jaw and bears the upper teeth. Lampreys ascend the rivers from the sea in the spring to deposit their spawn. They grow to 30 inches in length and 3 lbs. in weight. They were esteemed a delicacy in olden times, but they are not much eaten at the present day ; they are, nevertheless, wholesome food, and the historical incident firmly fixed in the memory of most schoolboys, that Henry I. died after a surfeit of Lampreys, should not be allowed to tell against them as an article of diet. In England the principal Lamprey fishery is in the Severn. The Lampern, Petromyzon fluviatilis, 1058, bears a general resemblance to the Lamprey, but it rarely attains a greater length than 16 inches, at all events in British rivers. It usually spends the whole of its life in fresh water, although some individuals have been caught in the sea. Its skin is not mottled as is that of the Lamprey, and the eye is relatively larger. The Lampern does not seem to prey upon living fish as does the Lamprey. It makes excellent bait for Cod and Turbot. Planer’s Lamprey, Petromyzon planeri, is smaller than the Lampern, and differs slightly in the arrangement of the teeth, the shape of the dorsal fin, and in its habit of living in the mud, whence it is sometimes called the Mud-Lamprey. The larval forms of the Lampern and Planer’s Lamprey are known as Lampern, Hag-fish. 6 FISH GALLERY. “ Ammoceete” (1063), or more popularly as Pride or Sand-piper. The Ammoccete differs from the adult in having no tongue or teeth, in possessing a hood-like anterior lip instead of an oral sucker, in the large size of the internal or pharyngeal apertures of the gill-pouches, and in the fact that the respiratory part of the pharynx is not shut off by a horizontal partition from the food channel. In South America and Australia the Lampreys are represented by the genera Mordacia and Geotria (1064). In the Hyperotreta the external nasal aperture is situated at the extremity of the snout, and from the inner end of the nasal sac there leads back a tube which opens into the roof of the pharynx (see dissection 1066). There are barbels on the snout. The skin is capable of secreting enormous quantities of glutinous slime. The eggs are large (see 1068). In Bdellostoma (1067) each gill- pouch has its own aperture on the side of the body, but in the Hag-fish, Myaxine, 1065, exhalent tubes from the pouches lead back and open together. Bdellostoma occurs plentifully in the bays along the Pacific coast of America; Myaine is found widely distributed in the temperate zones of the northern and southern hemispheres. Both feed on fish, and Myz#ine not infrequently bores its way into the abdominal cavity of the Cod. PISCES (Fishes). The Lancelet and Lampreys having been disposed of, there remain for consideration the true Fishes or Pisces, a class of the Vertebrata ranking equal with the Amphibia (Frogs and Newts), Reptilia (Turtles, Crocodiles, Lizards, Snakes), Aves (Birds), and Mammalia (Mammals, e. g. Rabbit, Dog, Horse, Man). Fishes are Vertebrate animals with a distinct and hinged lower jaw, passing their whole life in water (with a few exceptions), and possessing common distinctive characters in those systems of their organization which are in direct relation to their aquatic mode of life, namely, in the organs of respiration and locomotion. The vespiratory organs are gills, groups of delicate vascular filaments STRUCTURE OF FISHES. a projecting from the front and hind walls of the gill-slits, and supported by skeletal bars called branchial arches. An air-bladder is frequently present and serves as a hydrostatic organ or float, while in a few cases it may act as a lung and help the gills in their work of respiration. The organs of smell are paired, and only in rare cases (Lung-fishes) communicate with the mouth- cavity by internal nostrils. Except in the Lung-fishes the heart has but one auricle and receives only venous blood, which it forces, first through the blood-vessels of the gills and thence as arterial blood through the vessels of the body generally. The skin is either soft and bare or is hardened by the development of spines or denticles, or overlapping scales, or bony plates (scutes). Peculiar cutaneous sense-organs are distributed along the sides of the body (lateral line organs) and on the head, and appear to be specially associated with an aquatic mode of life. Such organs only occur elsewhere in Amphibians; in the tailless Amphibians (Frogs and Toads) they exist only in the larval or tadpole stages (except in the Cape-toad, Xenopus). The principal organ of locomotion is the powerful muscular tail; ‘this is assisted by the pectoral and pelvic limbs, paired fins corresponding with the fore and hind limbs of terrestrial Vertebrates. The skeleton of these paired fins cannot readily be compared with the limb-skeleton of other Vertebrates, there being no such bones as humerus, radius, carpal and phalangeal bones, and the edge of the fin is not divided into the five toes, which are, with exceptions, so regularly present in all other Vertebrates. Fishes also possess median fins on the back (dorsal fins) and between the anus and tail (anal fin) ; these fins are supported by skeletal bars or rays, whereas in Newts and other Vertebrates with median fins there are no skeletal structures in those fins. The scheme of classification adopted in the arrangement of the Fish Gallery is set out on pages 200-201. The systematic series of Fishes is exhibited in the Wall-cases, commencing with Wall-case 1 (Sharks and Dog-fishes) in the S.W. corner of the Gallery, and ending with Wall-case 20 (Angler-fishes, File-fishes, Globe-fishes, and Sun-fishes) in the S.E. corner. Standing on the floor of the Gallery or suspended from the roof are other Basking Shark. 8 FISH GALLERY. specimens, either too large to exhibit in the Wall-cases, or else constituting series of special interest, such as Deep-sea Fishes, Eggs and Young of Fishes, &c. CentraL Exarsits. The Table-cases 21 and 22, containing specimens of the Lancelet and of Lampreys and Hag-fishes, encountered by the visitor on entering from the Bird Gallery, have already been alluded to (pp. 2-6). In the same line is a third Table- case (23) containing a Port Jackson Shark, Cestracion philippi, four feet long, caught in Sydney Harbour in 1906. In the middle of this half of the Gallery, surrounded by a mahogany rail, is the cast of a skeleton of the Basking Shark, Selache maxima or Cetorhinus maximus, which was caught off Bergen, in Norway, in May 1901, and measured 283 feet. The Fic. 2,—Basking Shark, Selache maxuna. principal features of the skeleton of Sharks may be studied by reference to this specimen. The great jaws are connected with the cranium by the upper piece of the hyoid arch called the hyomandibular cartilage—a skull in which the jaws are so sus- pended is called ‘ hyostylic”’ (compare the “amphistylic” skull of Notidanus (Wall-case 1) and the “autostylic” skull of the Holocephali (Wall-case 5), and Dipnoi. The characters of the gill-arches and gill-rays are well shown in this specimen, as also BASKING SHARK. 9 are the features of the vertebral column, the pectoral and peivic girdles, and the skeletal parts of the pectoral, pelvic, dorsal, anal and caudal fins, except that the horny fin-rays are not reproduced in the cast. For an illustration of horny fin-rays the visitor is referred to the skeleton of the pectoral fin of the Dog-fish (8) in Wall-case 1. Hanging from the roof above the skeleton is a specimen of the Basking Shark, 28 feet long, caught off Bergen in 1904, and presented to the Museum by the Hon. Walter Rothschild. The Basking Shark grows to 33 feet or more. Its food consists of small fishes and other marine animals that swim in shoals. The gill-rakers are highly specialised, and serve to retain the smallest food organisms and to prevent their escaping through the gill- slits. On the west coast of Ireland the Basking Shark is caught for the sake of the oil obtained from the liver. The Shark is of a harmless disposition and does not attack man. On the left side of the skeleton is the head of a Basking Shark which was 28 feet long, and was caught in March 1875 near Shanklin, in the Isle of Wight*. This head shows the great size of the gill-slits, the right and left of which nearly meet under the throat, and the smallness of the teeth. On the other side of the skeleton are the pelvic fins of the same specimen, which was a male. The males of all Sharks have the pelvic fins produced backward into ‘claspers,” and the interest of the present specimen lies in the fact that the tooth-like bodies on the claspers of the Baskmg Shark were first known in the fossil state, and their true nature was only recognised when the Shanklin specimen was exhibited in the year 1876. Three examples of fossil clasper-spines are exhibited in the box adjoining. These are from the Red Crag of Suffolk ; similar specimens have been obtained from the Crag of Antwerp. Such spines were long a puzzle to paleontologists, by whom they were regarded as the terminal phalanges of some large Reptile or Mammal, or the separated lamelle of young teeth of a Mastodon or Mammoth, or the central cores of teeth of a Xiphioid Whale. * Figure 2 was drawn from this specimen. Rays. Side-rails. 10 FISH GALLERY. On the floor within the same railing are specimens of an Electric Ray, Torpedo hebetans, 1080, caught in the Menai Straits, North Wales, and a large Ray, Raia marginata, 1079, caught in Walfish Bay, South-west Africa. Hanging from the roof in the middle of the Gallery are two other large Rays, both from Muscat, in Arabia—an Hagle-Ray, Aétobatis narinari, and a Devil-Ray, Dicerobatis eregoodoo, a fish which grows to 15 feet in width, and is distinguished by the paired projection (head-fins) in front of the mouth. Beyond these Rays, also hanging from the roof, is a Whale Shark, Rhinodon typicus, the largest of all Sharks, growing to 50 or 60 feet in length; the specimen shown is not more than half the full size. The Whale Shark occurs mostly in the Indian and Pacific Oceans and has been caught off Florida and the Cape of Good Hope. Like the Basking Shark the Whale Shark is a slow-moving, apathetic fish, harmless to man, and often found basking or sleeping at the surface of the sea. The mouth and nasal openings are near the extremity of the broad, flat snout. The dorsal fin is much farther back than is that of the Basking Shark, and the gill-slits are not so large. The teeth are extremely small for so large an animal (see specimen 53 in Wall-case 1), and are closely set in regular rows in the form of a ribbon. The Whale Shark feeds on the minute semitransparent crustaceans and molluscs that abound at the surface of the sea, and to a certain extent also on sea-weed. Hanging from the roof at the North end of the Gallery is a large specimen of the Sun-fish, Orthagoriscus mola, trom Australia, and hanging near it is a smaller specimen of the same species caught off Dungeness in Kent (see fig. 3). Running the whole length of the Gallery are two side-rails suspended from the roof by chains. Hanging from these rails are, besides the Sun-fish just mentioned, a Sturgeon * (opposite Wall-cases 6 and 7), 10 feet 4 inches long, caught off the Dogger * For information concerning the structure and habits of these suspended fishes the visitor is referred to the accounts given in the description of the Systematic Series of Fishes exhibited in the Wall-cases. SUSPENDED SPECIMENS. ll Bank in 1873; a Saw-fish, Pristis pectinatus (in front of Wall- case 5) from Trinidad ; a Greenland Shark, Lemargus borealis (in front of Wall-cases 3 and 4), 15 feet long, caught on the Hast coast of Scotland in 1878; a Thresher or Fox Shark, Alopecias Fie. 5.—Rough Sunfish, Orthagoriseus mola. vulpes (opposite Wall-case 3), caught on the Devon coast in 1897; a Shark of the Indian Ocean, Ginglymostoma cirrhatum; and a Grey Shark, Notidanus griseus (opposite Wall-case 1) from the Orkney Isles. Floor- tase 27, 12 FISH GALLERY. On the other rail are an Odontaspis americanus (opposite Wall-case 20); an Elfin Shark, Mitsukurina owstoni, caught in 300 fathoms off Japan in 1903; an Indian Shark, Carcharias hemiedon, allied to the Blue Shark and White Shark, which are also species of Carcharias; a stuffed specimen and a pair of jaws of a Shark known as Galeocerdo rayneri, the teeth of which are curiously marked by a deep notch on the outer edge; a stuffed specimen and a pair of jaws of the Hammer-head Shark, Zygena malleus; and two Sting-Rays, Trygon brevicaudata, from New Zealand, and Trygon tuberculata, from Australia. Near the doorway at the North end of the Gallery and occupying a middle position between Wall-cases 8 and 13, is a Floor-case (27), which, at the time of writing, contains a Tarpon, Megalops atlanticus, 1110, seven feet long, presented in 1899 by His Majesty the King, then Prince of Wales; also a large Angler, Lophius piscatorius, 1016, and an Opah, Lampris luna, 1108, both presented by the Hon. Walter Rothschild; also a skeleton of the Opah, 1109. Close around this Floor-case are five Cabinet-cases (26, 28, 29, 80, 31) the arrangement of which is not at the time of writing sufficiently complete for description. They are intended for series of eggs and young of Fishes, nests and modes of protection of the young, long-bodied eel-like fishes of different families, Hlectric Fishes, Flyimg Fishes, Sound-producing fishes, fishes with poisonous flesh, fishes with poison-spines, fishes with suckers, fishes with accessory breathing-organs, hybrids in fishes, differences between male and female fishes, isinglass . from Sturgeon and Polynemus. In the vicinity of the Cabinet-cases are three skeletons under glass, standing on separate tables, namely, the Nile Perch, Lates niloticus (Table-case 33), from the Fayfm Lake, Egypt, a skeleton 55 inches long; a Parrot-fish, Pseudoscarus muricatus (Table-case 32), with the pharyngeal bones separated from the rest of the skeleton to show the curious pavement of pharyngeal teeth ; and a Stone Bass or Wreck-fish, Polyprion cernium (Table- case 34), of which a stuffed specimen is shown in the left upper part of Wall-case 13. FISHES IN TABLE-CASES, ETC. 13 On the large table between Wall-cases 6 and 15, surrounded by a mahogany rail, are a Great Blue Shark, Carcharodon rondeletii, from the Atlantic coast of North America, and, on the other side, a Mackerel Shark, Zamna spallanzani, and the jaws of a Mackerel Shark, and those of a Great Blue Shark much larger than the one shown on this table. On the floor within the railing are a number of specimens, the final positions for which have not at the time of writing been decided ; they are a skeleton of the Southern Ribbon- fish, Regalecus argenteus, a very fine specimen, 12 feet long; a specimen of Huorymetopon poeyi, a fish allied to the Hair-tails Wall-case 17) ; a skeleton of the deep-sea fish Alepidosaurus ferox, with great teeth and a large dorsal fin supported by unbranched fin-rays ; a form of Sea-perch, Epinephelus cerniides, not very large considermg to what a great size some of the Sea-perches or Jew-fishes attain, but interesting as being a specimen caught off the Cornish coast; a Meagre, Sciena aquila; a Skate, Raia batis ; a Sturgeon, Acipenser sturio; and a Quinnat Salmon, Oncho- rhynchus quinnat, which weighed 70 lbs. when caught. Standing between the two railed enclosures in the middle line of the Gallery is a Floor-case (24) devoted to the Sword-fishes and Sail-fishes. A description of the contents of this case is given on page 170. On one side of the Sword-fish case (24) is a small Table- case (37) containing a skeleton of one of the African Siluroids or Cat-fishes, Arius latiscutatus, and on the other side a Table (49) with a large Halibut, Mippoglossus vulgaris, 6 feet 2 inches long, caught in the North Sea in 1902, and a cast of a very fine Lepidotus maximus, from the Lithographic Stone of Bavaria, an extinct fish of the family Semionotidze (see Wall-case 7). In front of Wall-cases 6 and 7 stand two Table-cases (50 and 51) with a skeleton and two specimens of the great Arapaima gigas of the Amazon and neighbouring rivers, a fish belonging to the family Osteoglossidze (see Wall-case 7 and page 89). Opposite these cases, in front of Wall-cases 14 and 15, are two Table-cases (36 and 35) containing a large specimen of Platystoma gigas, from the Upper Amazons, and a skeleton of an equally large Bagarius Great Blue Shark. ; “Table 25. Tunny. British Salmon- oid Fishes. 14 FISH GALLERY. yarrellii from the Hugly ; both of these are Cat-fishes or Siluroids (see family Siluride, Wall-cases 9 and 10, and page 112). On the other side of the door-way leading into the Entrance Hall is a large Table-case, 38, standing in front of Wall-case 17, containing a very fine specimen of the Tunny, Thunnus thynnus (fig. 4), 8 feet long, caught in the English Channel off Weymouth, and also an Albacore, Thunnus alalonga; these are Scombroid or Fie. 4.—Tunny, Thunnus thynnus. (From Boulenger, Camb. Nat. Hist., vii, 1904, after Cuv. et Val.). Mackerel-like fishes (see Wall-case 15, and p. 165). Next follow four Table-cases (39, 40, 41, 42), with a Barracuda, Sphyrena commersonii, from Mauritius (see Wall-case 11 and p. 186); a large Sea-perch, Epinephelus lanceolatus, 7 feet 3 inches long, from the Indian Ocean (see family Serranide, Wall-case 13 and page 147); and a skeleton and a stuffed specimen of the Angler, Lophius piscatorius (family Lophiude, Wall-case 20, floor; see also page 193). In Cabinet-case 43, standing in front of Wall-case 20, are shown some Salmonoid Fishes of the British Isles; at the time of writing the series is very incomplete. Other specimens of Salmonoid Fishes are shown in the series of British Fresh-water Fishes in the North Wall-case of the Pavilion at the West end of the Bird Gallery, and some in Wall-case 7 of this Gallery. The tendency of modern students of fishes is to diminish the number of species to which Salmonoid fishes are relegated, and to regard the colouring of the body as of little account compared with such characters as SALMONOID FISHES. : 15 the size of the scales, and the number of rows in which they are arranged, the positions of the fins and the number of fin-rays in each, the characters of the teeth and the proportions of the bones of the upper jaw and of the gill cover, these characters being reasonably stable, whereas the colouring is largely dependent on the conditions in which the fishes live. As a rule the fresh-water forms are brown or reddish, and the marine forms bright and silvery, and in the case of migratory forms like the Salmon and Sea Trout the change from the one colour to the other is to be observed in the same individual at different periods of its life. In the non-migratory forms the colours are fairly constant while the fish remains in the same waters, but by transferring to new localities brown forms may become silvery and silvery forms brown. The relation that obtains between the environmental conditions and the colouring of the fish is expressed by Dr. Giinther * in the following terms :—“‘ Trout with intense ocellated spots are generally found in clear rapid rivers and in small open alpine pools; in the large lakes with pebbly bottom the fish are bright and silvery, and the ocellated spots are mixed with or replaced by X-shaped black spots ; in pools or parts of lakes with muddy or peaty bottom the trout are of a darker colour generally ; and when enclosed in caves or holes they may assume an almost uniform blackish coloration.” The remarkable differences in the colouring of Trout living in neighbouring, but non-communicating, waters is nowhere better exemplified than in Sutherland. Loch Scourie, Loch Crocach, Loch Borlane and Loch Manse all have their own particular type of Trout (see 995, 997, 996, 994). In deep lakes where food is fairly abundant the Trout grow to a large size, and such fish are called Great Lake Trout, fishes long known as Salmo ferox. The specimen of Great Lake Trout, 999, exhibited in the Cabinet-case, is from Windermere. In Loch Leven the Trout, formerly described as Salmo levenensis, are slender and more silvery than most non-migratory Trout, with less yellow along the sides of the abdomen and with spots that are dark and without any scarlet. Examples of a male and a female are shown (991, 992). The Galway Trout, of which a specimen * “ An Introduction to the Study of Fishes,” 1880, p, 632 Jule Deep-sea Fishes. 16 FISH GALLERY. from Connemara is shown, 998, is the fish described by some authorities as Salmo gallivensis; it is a robust fish of estuarine habit. Another Irish Trout is 998, a fish from Lough Arrow in Sligo. The Sea Trout is represented by an 84]b. fish caught in the sea at Montrose, a 7 lb. fish caught in the Tay at Perth, and a Smolt from the Tay, caught in May. If the colouring of the body be disregarded, the British species of Salmo may be reduced to three, namely, Salmo salar, the Salmon and its varieties, Salmo trutta, including all the Trouts, such as Salmon Trout, Bull Trout, Great Lake Trout and Brook Trout, and Salmo alpinus, acluding all the Charrs. At the time of writing the Charr is represented in Cabinet-case 43 by three specimens, from Buttermere, Windermere and Loch Scourie respectively. Deep-sea Fishes (see Cabinet-case 44) are not fishes of any particular order, but are fishes of genera belonging to numerous families more or less unrelated which have a deep-sea habit, the other members of the families being surface forms or coast forms. The proportions of the deep-sea genera to the others varies in different families. The families Alepocephalidz (Wall-case 7), Stomiatidz (Wall-case 7), Scopelidee (Wall-case 10), Halosauridze (Wall-case 10), Macruride (Wall-Case 11), Ceratiide (Wall- case 20) consist almost entirely of deep-sea forms, whereas among the Eels (Wall-case 8) and Gadidze (Wall-case 11) a moderate proportion of the genera occur in deep water, and in the Salmonidze only a very few, such as the Argentine (295, Wall-case 7). While the animals that live in shallow seas near the coast— animals such as fishes, crustaceans, molluscs, worms and jelly- fishes—exhibit considerable differences in different parts of the world, this is not the case with the animals which inhabit the deeper parts of the sea. The species of deep-sea fishes and other animals which are at all well known have a wide distribution. Removed from the glare of the sun, the fishes of the deep seas have become modified in relation with the subdued light in various directions. Most have exceptionally large eyes (e.g. Aphanopus, 982, Cabinet-case 44), so as to bring to a focus as much as possible of the faint light that succeeds in penetrating to the great depths ; a few have eyes which have undergone so much reduction that the fishes are blind, and rely for the capture of their food upon the DEEP-SEA FISHES. 17 increased acuteness of sense organs other than the eyes; some again are uniformly phosphorescent or have special luminous organs on the head or in series along the body. Most are of a pale green or blue colour when caught (see coloured sketches 980 and 981), but they rapidly turn black; it is for this reason that the coloration of many of the models shown is blackish. Some deep-sea fishes are colourless and gelatinous in appearance (e.g. Aphyonus, 974). In those which are coloured the coloration is mostly uniform, without spots or bands, and without the belly being paler than the back and sides. A few are silvery (e. g. Lepidopus, 971). Many fishes obtained from great depths come to the surface in a damaged condition owing to the expansion of the gases in the tissues of the body when relieved from the great pressure to which they are subjected at the bottom of the sea. For this reason few Fia. 5.—A Deep-sea Fish, Maiacosteus undicus. (From Boulenger, Camb. Nat. Hist. vii, 1904, after Gunther.) are suitable for exhibition, and most of the specimens shown in Cabinet-case 44 are models, some of them enlarged, made to present as nearly as possible the appearance that the fishes would offer in their natural state. Most of the deep-sea fishes are known by a few specimens only, and, being rare, they have no popular names. Aulostomatomorpha (984) is a curious fish in, whichalmost the whole of the skin of the head is phosphorescent ; in Malacosteus (979, and fig. 5) there are two photophores or luminous organs situated below and behind the large eye ; in Jpnops (976) the eyes are wanting and the top of the broad, flat head is occupied by a pair of large photophores, which nearly touch one another in the middle line. Cc 18 FISH GALLERY. Gastrostomus (985, fig. 6 a) and Saccopharyne (986, fig. 6 b) are related to the Hels; they are predaceous fishes, with the eyes set Fie. 6.—T wo Deep-sea Fishes allied to the Hels: a, Gastrostomus burdi, and b, Saccopharynx flagellum. SSS = a ap Fic. 7,—A Deep-sea Fish, Chiasmodon nigrum. (From Giinther, “ Study of Fishes”.) very far forward, and with a long tail tapering off to a thread. The former fish is remarkable for the enormous size of the mouth. Both are provided with a highly distensible stomach and abdominal DEEP-SEA FISHES. 19 wall, by virtue of which the shape of the fish is greatly changed after a good meal. In the case of Saccopharynx (986), for instance, the size of the abdomen is due to the fish having swallowed another fish of considerable size shortly before it was itself caught. A still more remarkable case is that of Chiasmodon (978, fig. 7), which prior to capture had devoured a fish larger than itself, and the shape of which was clearly discernible through the tightly stretched wall of the distended abdomen when the fish came to hand. Chauliodus (975, and fig. 8) is a fairly common deep-sea fish, chiefly remarkable for the great length of its teeth. Bathypterois (983) is a small-eyed fish presenting a great elongation of the uppermost ray of the pectoral fin and the foremost two rays of the pelvic fin ; these filamentous rays are doubtless used as “ feelers.” A similar function may be attributed to the rays of the paired fins of Paraliparis (973), a fish allied to the Sea-snails (Liparis, 836 and 837, Wall-case 19) of the English coast. =—S Ss7z TTY is SS. WG TTT AN \ K Sr SA rr TTI CORRS p \\\ cK Se ZEA SUNN NNNS Sas vn MS \ iit IS SHAN S ZY’|, jp fly) NN Oa Gwe Fre. 8.—A Deep-sea Fish, Chauliodus sloanit. (From Giinther, “Study of Fishes.”’) Dolopichthys (972) is a fish belonging to the Ceratiidee, a deep- sea family related to the Angler-fishes. The “lure,” which serves as a bait to induce the prey to come within reach of the jaws, and which is suspended from the end of a long fin-ray of the dorsal fin, is in Dolopichthys a luminous structure. The fishes represented in Cabinet-case 44 are only the most striking and exceptional of the deep-sea fishes. ‘Those less modified _are shown in the systematic series in the Wall-cases. c2 20 FISH GALLERY. Following Cabinet-case 44, in a series along the side of the Gallery, are four Table-cases (45-48) with a skeleton of the Porbeagle Shark, Lamna cornubica (see the specimen in the upper part of Wall-case 1, see also page 32) ; a Jew-fish, Sterco- lepis gigas, a Sea-perch allied to the large specimen in Table- case 40 in a corresponding position on the other side of the Gallery ; a Southern Meagre, Sciena antarctica, and a skeleton of the Common Meagre, Sciena aquila (family Scizenide, Wall- case 13; see also page 151) ; and another form of Meagre, Scena diacanthus, from the estuaries of Bengal. SysTEMATIC SERIES IN THE WALL-CASES. In Wall-case 1, in the S.W. corner of the Gallery are exhibited the more primitive of the Sharks and Dog-fishes; the series of Sharks and Dog-fishes is continued in Wall-case 2 and ends with the Monk-fish and Pristiophorus. In Wall-cases 3 and 4 are shown the Saw-fishes, Skates and Rays, and in the lower part of Wall-case 4 reference is made to the extinct Pleuracanthodian Sharks, Wall-case 5 is devoted to the Holocephali and Ostra- codermi. The Dipnoi or Lung-fishes occupy the first part of Wall-case 6, the Stylopterygu or Fringe-finned fishes, and the Sturgeons and Gar-pikes fill up the rest of the case. In Wall- case 7 are the Amioid fishes and their extinct relatives, also the lower Teleostean fishes, the Herring-like and Salmon-like fishes. Wall-case 8 contains the Carps and their allies, and, on the floor, the Hels ; the Cat-fishes occupy the corner case (9) and a part of Wall-case 10, the rest of which is filled by the Pikes, Sticklebacks, Sea-horses, Pipe-fishes, &c. In Wall-case 11 are shown the Grey Mullets, Flying-fishes, and Barracudas, and the Cod-like fishes. In the corner case (12) begins the great series of fishes with spiny fin-rays in the dorsal, © anal and pelvic fins (Acanthopterygian fishes), a series which continues along the whole of the East side of the Gallery up to Wall-case 19. The first fishes of the series are the Berycoid SHARKS AND RAYS. 21 fishes, in Wall-case 12, together with the Archer-fish and the Perch, and in Wall-case 13 there follow the Sea-perches, Basses and Meagres. The Snappers, Sea-Breams, Red Mullets and Chietodont fishes are shown in Wall-case 14, and the Surgeon-fishes, Parrot-fishes, Wrasses and Mackerel-like fishes in Wall-case 15. The small Wall-case 16 is devoted to the Horse-Mackerels, and Wall-case 17 to the Frost-fishes and Dolphin-fishes. Wall- case 18 includes the Dorys, the Flat-fishes, such as the Sole, Plaice and Turbot, and the Sucking-fishes and Gobies. In the upper part of Wall-case 19 are exhibited life-sized coloured drawings of the Ribbon-fishes, and in other parts of the case are specimens of Gurnards, Lump-suckers and Blennies. The systematic series ends with Wall-case 20, which contains the Angler-fishes (on the floor), the File-fishes, Globe-fishes and Sun-fishes. ELASMOBRANCHII (Sharks and Rays). The Elasmobranchii, including the Sharks, Dog-fishes, Saw- fishes, Skates and Rays, are marie fishes with a skeleton composed of cartilage, the surface of which is usually calcified, but does not exhibit the characters of true bone. The skin possesses tooth-lke structures called placoid spines, which when closely set constitute shagreen. The vertebral column is in most instances continued into the upper part of the tail fin, and the lower lobe is small as compared with the upper; such a tail is known as “ heterocercal.” The fins are supported by closely-set rods and plates of cartilage in the basal parts, and by horny fin-rays in the marginal parts (see specimen 3). There is no gill-cover, and, with a few ex- ceptions, five gill-slits open on each side of the body. The heart has a chamber known as the conus arteriosus, which is provided with watch-pocket valves that prevent the return of blood to the ‘ventricle (see dissection 2). The intestine has a spiral valve (see dissection 1) and there is no swim-bladder. The ova or egg-cells are large, and undergo their development either within the body of Wall- case 1, Cladose- lache. 22 FISH GALLERY. the mother or within horny egg-shells (see specimens 7, 4, 5, 6 and fig. 9). In the scheme of classification adopted in this Gallery Fie. 9.—Kgeg of a Dog-fish of the genus Scylliwm. (From Giinther, “ Study of Fishes.”) (see pp. 200-201) the Elasmobranchii are divided into four orders, Proselachu, Acanthodides, Selachii, and Pleuracanthodes. PROSELACHII (Primeval Sharks). The Proselachii or Pleuropterygii are extinct Sharks, the most primitive as weil as the most ancient of the Elasmobranchi. The only genus of which the general structure is at all well known is Cladoselache (fig. 10), but detached teeth resembling those of Cladoselache have long been known in the Carboniferous formations under the name of Cladodus (see tooth of Cladodus striatus, 10). The gill-slits are five or more in number ; the upper and lower jaws are approximately equal in size and are suspended from the cranium by the hyomandibular cartilage. The dorsal and the paired fins are supported by parallel fin-rays of calcified cartilage which extend nearly to the margin of the fin. Dermal fin-rays have been described in the posterior edge of the fin, but the evidence of their presence is unsatisfactory (see pectoral fin, 8). The length of these Sharks varies between two and six feet. The remains of Cladoselache fyleri, found in the Cleveland Shale (Upper Devonian or Lower Carboniferous) of Ohio, are sufficient to show that the form of the body was rounded and PRIMEVAL SHARKS, 23 elongated (see fig. 10, and the enlarged drawing 9 at the top of Wall-case 1). Two dorsal fins are present, but no anal fin. The caudal portion of the vertebral axis is strongly upturned, and distinctly hinged upon the rest of the vertebral column, but the outline of the tail is symmetrical about a horizontal plane. A Fie. 10.—An extinct and archaic Shark, Cladoselache fyleri, side and ventral views, restored. (From Bridge, Camb. Nat. Hist., vii, 1904, after B. Dean.) short dermal expansion forms a horizontal keel on each side of the base of the tail. No calcifications are recognisable in the sheath of the notochord ; the skeletal cartilages are calcified in the form of cubes, closely fitting like a mosaic. The teeth are of various forms, each with a principal cusp and a variable number of lateral cusps. The eye has a ring of small dermal plates; the remainder of the body is covered with minute denticles. ACANTHODIDES (Acanthodian Sharks). The Acanthodian fishes are Paleeozoic Sharks of small size, rarely exceeding one foot in length. The restoration of Climatius shown (11) is about four times the natural size (linear). The Climatius, 24 FISH GALLERY. placoids of the skin are flattened and closely fitted together. The calcifications of the cranium, jaws, and pectoral girdle present the appearance of membrane bones, although bone cells are wanting. The fins, both paired and median (except the caudal), bear each a stout spine along the front edge, and in some cases there occur ' between the pectoral and pelvic fin of each side a row of four or five spines of a similar nature (see 11, and fig. 11). The cartilaginous supports of the fins must have been insignificant, and the fin- membranes but feebly supported by dermal fin-rays. The earlier forms, those of the Upper Silurian and Lower Devonian, are included in the family Diplacanthide (e.g. Diplacanthus and Ch- matius) ; these have two dorsal fins. The family Acanthodide (e. g. Acanthodes) includes the later forms, those ranging from the Lower Devonian to the Lower Permian, which have but a single dorsal fin, and pelvic fins of smaller size than the pectorals. In Cli- matius (11) the fin-spines are remarkably broad, and are marked with coarse longitudinal ridges. The most perfect specimens known are about seven inches in length, but fragments have been found of specimens which must have measured eighteen inches or more when complete. SELACHII (Modern Sharks and Rays). The order Selachii includes all the modern Sharks and Rays, and a number of extinct forms as well. The great majority of the Selachii are marine, but a few species live in fresh water. The denticles of the skin are closely set to form shagreen, but in the Rays there is a tendency for the spines to become fewer and larger. The calcifications on the surface of the cartilages do not resemble membrane bones, and have not the microscopic structure of true bone. The basal cartilages of the pectoral fin, namely, those in contact with the pectoral girdle, are usually three in number, less commonly two; there is no long segmented axis to the fin. With a few exceptions the vertebral centra are well calcified, but the form of the calcified layers varies considerably (compare specimens 20, 28, 65, 80, 85, 90, 113 in Wall-cases 1-4). The Selachii range back to Carboniferous and Permian times. The suborders recognised are :—Notidani, Squali, and Rai. ACANTHODIAN SHARK. Fie, 11,—An Acanthodian Shark, Climatius macnicoli, restored. Chlamy- dosela- chus. Noti- danus. 26 FISH GALLERY. Noripant (Notidanid Sharks). The Notidani constitute a small suborder of archaic Sharks in which the gill-openings are Six or seven on each side of the body. The vertebral column is imperfectly segmented, and the centra are feebly if at all calcified ; there is but a single dorsal fin, which is, set rather far back, opposite the anal fin. There is no nictitating membrane or third eyelid, such as occurs in some Sharks (e. g. 67, Wall-case 2). There are two families, the Chlamydoselachide and the Notidanide. The family Chlamydoselachide includes but a single genus, Chlamydoselachus, a long, slender-bodied Shark (specimen 12, and fig. 12) found in the deep seas of many parts of the world, and first obtained off the coast of Japan in 1884. The head is depressed, and the mouth is terminal. There are six pairs of gill-openings, with backwardly directed frills or flaps of skin, whence the popular name “ Frilled Shark” given to this fish. The skull is hyostylic, 2. e. the jaws are suspended from the cranium by means of the upper element of the hyoid arch (for illustration of ‘““hyostylic”” see specimen 18). The teeth are of primitive character and several rows are simultaneously in use ; the crown consists of three slender curved cusps, separated by a pair of small denticles ; the embedded bases are broad and backwardly extended, and overlap one another in the gum. In the Notidanidz the skull differs from that of the previous family in being “ amphistylic,” 2. e. the jaws are connected with the cranium or brain-case in two ways, by a direct articu- lation between the upper jaw and the optic region of the cranium, and by means of the hyomandibular cartilage, or upper piece of the Fic, 12.—Frilled Shark, Chlamydoselachus anguineus, NOTIDANID SHARKS. ib hyoid arch, which is much more slender than is usual in Sharks (see skull of Notidanus, 13, and compare with the hyostylice skull of Scyllium, 18). The mouth is inferior ; the gill-clefts are six in number on each side in Hexanchus and seven in Heptanchus; there are no flaps or frills over the gill-clefts. The teeth have a characteristic form (see 15, and fig. 13), and in the Fie. 13.—Tooth of Wein EL sae aes eat a a = gigas. use at atime. The principal teeth in their most perfect development pos- sess a number of backwardly-sloping compressed cusps arising from a long base; the anterior edge of the first cusp is finely serrated. The teeth at the front of the upper jaw are smaller, and have each a single awl-shaped cusp with one or more small lateral cusps. The teeth of Notidanus are found in rocks as old as the Jurassic ; examples are shown (164 and B) of fossil teeth of Tertiary age. The Notidanid Sharks attain to a length of fifteen feet, and are distributed over the tropical and sub-tropical seas. In Wall-case 1 is shown a small specimen of the Perlon or Seven- gilled Shark, Notidanus (/Teptanchus) indicus, 14, and suspended from the rail in front of the case is a Grey Shark, or Six-gilled Shark, Notidanus (Hexanchus) griseus, 1141, caught off the Orkney Isles. Squat (Sharks and Dog-fishes). In the suborder Squali are included all the Sharks and Dog- fishes except the few embraced in the former suborder, the Notidani. There are two dorsal fins instead of one and the gill- clefts are five in number on each side. These fishes differ from those of the following suborder, the Raii (Wall-case 3), in the gill-clefts being laterally placed, and in the body being of the usual Shark type, without any great enlargement of the pectoral fins er flattening of the body. The Rhinidz show a tendency to modification in these directions, although they do not necessarily lead on to the Rays. It is convenient to divide the suborder into two groups, which may be designated Group A and Group B. Group A of Squali. Port Jackson Shark. 28 FISH GALLERY. In the fishes of Group A an anal fin is present between the cloaca and the tail fin, and there is a tendency for the spiracle to become reduced in size. The vertebral centra are astero-spondylic, i, e. if viewed in transverse section they are seen to be strengthened by calcified ridges or radiatmg lamin which predominate over the concentrically disposed laminze (compare the asterospondylic vertebree of Cestracion (20) and Scyllium (28) with the tecto- spondylic vertebre of Rina (90, Wall-case 2). Group A (From Giinther, “ Study of Fishes.’’) includes the families Cestraciontide, Cochliodontide, Scyllude, Lamnide, Rhinodontide, and Carchariide. In the family Cestraciontide, the best-known example of which is the Port Jackson Shark (24), each of the two dorsal fins is armed with a stout spine (see spine, 24.4), and the first dorsal fin is opposite the space between the pectoral and pelvic fins. The nasal and buccal cavities are confluent; there is no nictitating membrane; the teeth, except those at the front of the mouth, are blunt, and adapted for crushing the shells of molluscs and crustaceans (see jaws, 19, and fig. 14). Sharks of this family PORT JACKSON SHARK. 29 existed in Carboniferous times and were more numerous in Paleozoic and Mesozoic periods than at the present day. In Cestracion the mouth is rather narrow and nearly terminal. The spiracle is small and situated below the posterior part of the eye; the gill openings are rather small. The dorsal fin-spines are smooth and with no posterior serrations such as occur in Hybodus (see spine, 21, and fig. 15). The jaws are suspended by the hyomandibular cartilage, but the upper jaw also enters into extensive articulation with the ethmoid region of the eranium (see skull of Cestracion galeatus, 17 ; the more usual type of hyostylic skull found in Sharks is illustrated by a skull of Scyllium, 18). The vertebral centra of Cestracion are asterospondylic (see 20), but the radiating arrangement of the secondary lamin of calcareous matter does not occur in the more ancient genera of the family, e. g. Hybodus and Paleospinax. The egg-shell of Cestracion has a curious spiral flange projecting from its surface (see 6). The species of Cestracion occur in the seas of Australia, Japan, California, &c. The specimen 24 shown in Wall-case 1 is a small example of the Port Jackson Shark ; a larger specimen (four feet long) is shown in the Table-case 23, in the centre line of the Gallery ; a full-sized individual is about five feet long. For comparison with the teeth of Cestracion (19) are shown the teeth of the extinct Acrodus (22) and Asteracanthus (23). The Sharks of the family Cochliodontide so flourished in Carboniferous times, and their spine of Hybodus. ; : (From Giinther, "mains are practically confined to the rocks of “Study ofFishes.”) that age. The dentition differs from that of the Cestraciontide in one or more of the transverse series of teeth being fused into a continuous curved plate. Whereas in Cestracion the reserve members of the series of crushing teeth arise as separate teeth on the lingual or inner Cochli- odus.. Dog- fishes. Spotted Dog-fish. 30 FISH GALLERY. side of those in use, in Cochliodus the teeth are coalesced into a continuous plate, which receives additions to its lingual border and slowly moves outward and forward in a spiral manner over the surface of the jaw. ‘Two views are given of the dental scroll of Cochliodus, 25 and 26 (see also fig. 16). In the family Scyllide the dorsal fins have no spines; the first is situated above or behind the pelvic fins. The spiracle is distinct; there is no nictitating membrane. The teeth are small and several series are in use at the same time. The nasal and buccal cavities are more or less confluent ; the fourth and fifth gill-slits are close together in the genera Chiloscyllium, Crossorhinus, Ginglymos- toma, and Stegostoma, but not in Seyllium. The common Dog-fish of the South coast of England is Scyllium cantcula, 30. The plates of qMaeegneaue term “‘ Dog-fish ” is applied loosely toany con tortus. small Shark-like fish, the difference between (From Giinther, “Study a Dog-fish anda Shark being one of size of Fishes.”) only*. The Dog-fishes found around the British coast include the one just mentioned, Scyllium canicula, 30, the Smaller Spotted Dog-fish; the Larger Spotted Dog-fish or Nurse Hound, Scyllium catulus, 27; and the following three which do not belong to the family at present under considera- tion, the Piked Dog-fish, Acanthias vulgaris (75, in Wall-case 2), a Dog-fish which on the East coast is more common than the Spotted Dog-fish ; the Smooth Hound, Mustelus vulgaris (68, Wall-case 2), and the Tope, Galeus canis (64, Wall-case2). The commonest of these are the Smaller Spotted Dog-fish and the Piked Dog-fish, which in some parts of the coast are sufficiently plentiful to prove troublesome to fishermen by taking the bait intended for more valuable fish. The Spotted Dog-fishes are ground feeders and live mostly on crustaceans and molluses, and they keep fairly close to the land. On some parts of the coast these Dog-fishes are eaten, but the flesh is not in great favour. The smaller Dog-fish is distinguished from Fic. 16.—Jaw with tooth- * This does not apply to extinct forms. Acanthodian fishes, for instance, rarely exceed a foot in length, but it is customary to speak of them as “ Shariks,”” DOG-FISHES, ol the larger, not only by its smaller size, but by its anal fin being situated farther forward as compared with the second dorsal fin, and the right and left nasal flaps are nearly continuous in front of the mouth, whereas in Scylliwm catulus they are some distance apart. These Dog-fishes lay pillow-shaped eggs with a flexible yellow-brown or black egg-shell, the four corners of which are | produced into tendril-like threads which serve to anchor the egg to sea-weed and rocks (see specimen 4 in the introductory series below the label “ Elasmobranchii”’). Two eggs are laid at a time, and five or six months elapse before the embryo fish hatches out. The Black-mouthed Dog-fish, Pristiurus melanostomus, 31, is a small Dog-fish common in the Mediterranean and occasionally caught in British seas ; it has a series of small flat spines on each side of the upper edge of the tail fin. The genus Ginglymostoma includes Sharks some of which grow to twelve feet in length, with small eyes and minute spiracles; they are of pelagic habit and occur in the warmer parts of the Atlantic and Indian Oceans. The specimen of Ginglymostoma brevicaudatum shown (83) is small, the jaws of the same species (34) give an idea of the size to which the fish grows.