b GWe@hSOO TOEO O WONT 00 IOHM/18lN ‘ ' * 4 1 = te - i ’ c 4 # w i i i Nr f f ; ae j A a a i . f t ¢ « i 1 { a A i a i ; t ; " \ i e e t i zm) ey i ? ’ i} i f i ( J i} i ip ’ Bil, e un : ; ‘ i i i i f i i i Jj | : i J if 1 i / el J 1 A ay i i ! a ; A al 7 i rey TaAlt i i : i! { j THE ELASMOBRANCH FISHES bp. - ~vi nea ELASMOBRANCH FISHES 6 Bigs. 1-9, 1. Cephaloseyllium, the California swell shar acanthias, 6, Torpedo (Tetronarce), the electric ra Storer; and 7 and 9, original.) 2. Alopias, the thresher. 3. Rhinodon typicus, the whale shark, 4. Cetorhinus (Selache) maximus, the basking shark. 5. Squalus Rhinobatis productus. 8. Myliobatis californicus, 9, Urolophus halleri. (From Garman, except figs. 3, from Bean; 2 and 4, from fare meASMOBRANCH Fist hs BY LORAIN DAWN LE Professor of Zoology in the University of California ENV RS LEY OF (CALLER O RIN TA PRESS prkieh LE oCALTREORNITA 1934 First Eprrion ISSUED JUNE, 1922 SECOND EpiITIon ISSUED APRIL, 1928 THIRD, REVISED, Epirion IssuED Marcu, 1934 CoPyYRIGHT, 1922 AND 1928 BY J. FRANK DANIEL COPYRIGHT, 1934 BY THE REGENTS OF THE UNIVERSITY OF CALIFORNIA SALES REPRESENTATIVES UNIVERSITY OF CALIFORNIA PRESS BERKELEY, CALIFORNIA CAMBRIDGE UNIVERSITY PRESS LONDON, ENGLAND For orders originating in Great Britain only PRINTED IN THE UNITED STATES OF AMERICA PREFACE TO FIRST EDITION Tue ELASMOBRANCH FisHeEs are, I believe, unsurpassed as material on which to study the fundamental plan of the vertebrate body. The ease with which a large, cartilaginous form may be dissected makes a study of its systems of organs a relatively simple matter, and the comparative simplicity of most of the systems shows that at least some of the present-day Elasmobranchs closely approximate the early vertebrates. The importance of the shark as a type for classroom study has, I think, not been generally appreciated in this country. This has been due in part to the difficulty of obtaining specimens in centers removed from the seaboard; in part, it has been due to the paucity of available literature. This I say in face of the fact that an abundant literature in practically all languages exists. I have attempted to remedy this latter difficulty by adding to each chapter a working bibliography. In my studies of the Elasmobranchs I have been fortunate in having at hand perhaps the most generalized of these fishes, Heptanchus maculatus. In addi- tion to a study of the systems of organs in this and in other forms, I have at- tempted to collect and unify the work done by many workers on the various types. These combined studies I present with the hope that they will serve as a guide for undergraduate students of college grade, and at the same time be sufficiently inclusive to be used as a book of reference on the entire subject. I am indebted to the Scripps Institution for Biological Research for liberal support during five summers at La Jolla, and to the Research Board of the University of California for a grant in the final finishing of the plates. I am further indebted to many students who have helped me. Among them I single out Dunean Dunning, who, as a sophomore and junior student, made many of the most important drawings in the book. J. FRANK DANIEL BERKELEY, CALIFORNIA, January 16, 1922. PREFACE TO SECOND EDITION IN THE SECOND EDITION of the Elasmobranch Fishes I have followed the same plan as in the first, but I have added subject-matter and illustration which should make this edition somewhat more complete. Especially is this true for the chapter on the blood system to which has been added the work of Keys on the hypobranchial arteries of Hexanchus. The findings on Hexanchus supple- ment and add to my work on Heptanchus and make it more certain that the blood supply to the pectoral area in primitive vertebrates was from the hypo- branchial system, rather than from the dorsal aorta (the subclavians) as is true for higher vertebrates. | have also included in this edition Professor Van Wijhe’s discovery that the thymus gland in the embryo of Heptanchus cinereus is not ductless, and I have added experimental evidence to show that the cutaneous vessels in Elasmobranchs are true blood-vessels. BERKELEY, CALIFORNIA, J. FRANK DANIEL February 24, 1928. PREFACE TO THIRD EDITION AMONG THE CONTRIBUTIONS ADDED to the third edition of Elasmobranch Fishes is the work of Marine on the transformation of the endostyle of Ammocoetes into the thyroid gland of the adult Cyclostome. Other contributions made since the publication of the second edition are on the lymphatic system by Hoyer, on the external carotid artery by O’Donoghue, and on the ampullae of Lorenzini by Dotterweich. O’Donoghue has shown that the external carotid in Elasmobranchs, as in higher types, belongs to the lower jaw, and that the artery in the orbit pre- viously designated as the external carotid or posterior carotid is, in fact, com- parable to the stapedial artery of mammals. Through this work we now have a complete history of the externa! carotid artery from sharks to man. Dotterweich has shown that the wall of an ampulla of Lorenzini is made up of two types of cells. One of these, a large goblet or gland cell, pours its secre- tion into the ampulla; the other type is pyramidal and has an inside hex- agonal face which is sensory in nature. An efferent nerve supplies the gland cell, and an afferent nerve leaves each of the sensory cells. BERKELEY, CALIFORNIA, J. FRANK DANIEL January 4, 1934. [vi] CONTENTS Introduction . I. EXTERNAL FORM External Form of Heptanchus maculatus . External Form of Elasmobranchs in General . Transitional series External form in its deeclopmene: Form and position of adult fins . External form of fin and its bearing on Ginetion Form of fin in its beginning . Bibliography Il. INTEGUMENT Integument of Heptanchus maculatus . Modified scales : Integument of leew obranehen in (Conerale Gland cells Glands of claspers E Poison glands of sting ray . Light organs Placoid scales Finer anatomy of scale Modification of scales Fin spine Saw tooth . Stine. 2 2 Gill rakers . ; Stomodeal denticles . Teeth as modified scales Bibliography III. ENDOSKELETON Endoskeleton of Heptanchus maculatus Axial skeleton Skull . Visceral skeleton Spinal column . ; Appendicular skeleton Skeleton of paired fins Skeleton of unpaired fins Dorsal fin Caudal fin Anal fin. : Endoskeleton of Hlaemobranchal in cell Axial skeleton Skull . Cranium . ; Visceral skeleton Extravisceral arches . Spinal column . [vii] 26052 PAGE 26 28 28 Endoskeleton of Elasmobranchs in General—Continued PAGE Appendicular skeleton . . . PERO, Ne re co EUS Skeleton of paired fins and of ap Pordien Age ee s, S ag a ae aera ae cane I) Rectoralstingskelevomey Gin. 2 eeteesh oe bey eikke) “kets cu Ce en ectoral @irdlevee ©" sf fs ke as = eo at ek ee Pelweranuskeleton 6) 2 02 2 <-- & ‘geek “2 cs Gy ee ee Pelvic girdle beh lo, \bes. RG RS eee ae ee Te ee Skeleton of unpaired fins: ws 4. <4 (ee a) fet vate gt): Je ee Biphorraphy |="... +... USE cTRASSE AS Ge cs cto eos ee get IV. MUSCULATURE Musculature of Heptanchus maculatus ae oe Ee a a eel Toho) Muscles of theeye . . 5 ae en alee ee ede Dyes 3. GY) Buccal and pharyngeal TATO GS eR, AS Pa go ee OU Dorsaliconstrictorse= 2. = fo ay eR ee ee oe ee Ventraliconstrictorss # af. co eowe OR Ae, OnE IMteTATCUALCSH. “Sue Gros ee oS ke oS: ek Gh wie toes oebl ate, a nee Adductors . . a or eee ees EE Ventral longitudinal meen a eee PY MeN ee ble a a Ge er Muscles of the fins . . . eM ER oF ate Apes a an CE Musculature of Elasmobranchs in General ja fet 2s wile, of. o- SSR SO IMusclesvofatheteye. 49 © 2 & 202 6 ‘ew tee sul seine) eee eee INuscles ofmvasceralvarches@ec s)he eae eee Superficial constrictors of pharynx- . . . . .°. . . » «= . % = —etOr Dorsal constrictors oo ee oe we Pe Ue ee vee SA cp mci OO Ventral constrictors. . « «9. .-« « « 5 « «© % © cee uueeMenne Deeper muscles of pharynx << : 2 «= = + 3 «+.» > oSiine Beate Imnterarcusles. a) a0.) 242) sO le as