118 STUDIES ON THE ELASM03RANCH SKELETON, 



Explanation of the Plates. 



Au — Auditory apertures in parietal groove. Ar — Articular surface for 

 hyo-mandibular. PSC — posterior semi-circular canal. ASC— anterior 

 seini-circular canal. Po — post-orbital process. Pr 0— prse-orbital 

 process, fo — fontanelle. or— foramen of exit of ophthalmic nerve from the 

 orbit— op 1 foramen by which the ophthalmic nerve passes downwards and 

 outwards towards the nasal capsule (posterior opening of the ethmoidal 

 canal ) R — rostrum. 01 — Olfactory capsule. Vg — foramen of exit of the 

 vagus nerve. II— foramen for the optic nerve. Bp — Basal plate. PI-- 

 palato-quadrate. Mck — -Meckel's cartilage. HM — hyo-mandibular. Hy — 

 hyoid arch. Br 1 , Br 2 , etc. — Branchial arches, p pt — propterygium. m pt — 

 mesopterygium. mt pt — metapterygium. p — pectoral arch, pi— pelvic 

 arch, ppt' — anterior basal cartilage of pelvic fin. m pt' —middle basal carti- 

 lage of pelvic fin. mt pt' posterior basal cartilage of pelvic fin. cl. — axial 

 cartilage of clasper. 



Plate I. 



Fig. 1. Skull of Carcharodon Rondeletii from above. 

 „ 2. The same from the side. 

 ,, 3. Pectoral fin of the same. 

 ,, 4. Dorsal fin of the same. 



,, 5. Pelvic fin of Heptanchus indicus. M pt! — mesial basal cartilage . 

 ,, 6. Skull of Crossorhhius barbatus from above. 

 ,. 7. Pectoral fin of the same. 

 ,, 8. Pelvic fin of the same. 



,, 9. Skull of Pristiophorus cirratus from above. 



„ 10. Branchial skeleton of the same. 



„ 11. Pectoral arch and pectoral fins of the same. 



,, 12. Pelvic arch and pelvic fins of the same. 



Plate II. 



Fig. 1. Skull of Trygonorhina faseiata from above. 

 ,, 2. Branchial skeleton of the same. 



j, 3. Lateral view of pectoral arch of the same. Sf — superior nerve- 

 foramina, if, inferior nerve foramina, p, facet for propterygium. 

 m, facet for mesopterygium. mt, facet for metapterygium. 

 ,, 4. Pectoral fin of the same— r — rays articulating directly with the 



pectoral arch. 

 ,, 5. Pelvic arch and pelvic fins of the same. 

 ,, 6. Skull of Hyjmos subniger. 



„ 7- Diagram showmg the connections of the hyo-mandibular, the 

 hyoid, and the first branchial arch with the skull in Hypnos 

 subnig r. 



