52 AN EXTRAORDINARY SHARK ; 



body and the sides of the head and tail. The smaller 

 Sketches show the upper and lower surfaces of the head. 

 The smallest figures give the outlines of a tooth viewed 

 froni above and from the sides. 



From the foregoing it appears that there is neither 

 genus nor family to which the species described may prop- 

 erly be assigned. The characters given below are se- 

 lected for provisional diagnoses. 



Chlamydoselachus. Branchial apertures six. Oper- 

 cular Aap broad, free across the isthmus. Teeth simihir 

 inboth jaws, with slender subconical cusps and broad 

 backward produced bases. No teeth in the middle in 

 front above ; a row on the Symphysis below. Mouth wide, 

 anterior ; no labial fold. No nictitating membrane. Fins 

 broad, pectorals far in advance of the others. Caudal 

 without a notch posteriorly. Gill arches slender, long, 

 basihyal not wide. Intestine small. 



CHLAMYDOSELACHiDiE. Body much elongate, increas- 

 ing in size very little anter iorly. Head depressed, broad. 

 Eyes lateral, without nictitating membrane. Nasal cav- 

 ity in skull separate from that of mouth. Mouth anterior. 

 Snout broad, projecting very little. Cusps of teeth re- 

 sembling teeth of serpents. Spiracles small, behind the 

 head. One dorsal, without spine. Caudal without pit at 

 its root. Opercular Aap covering first branchial aperture 

 free across the isthmus. Intestine with spiral valve. 



