The ?iatural History of the Frilled Shar\ 315 



C. LAWLETL — The first discovered fossil form was named by J. W. Davis in 1887 

 from a description by R. Lawley (1876) of two complete and seven fragmentary teeth from 

 the Pliocene of Tuscany. These teeth much more closely resemble those of the recent 

 fish, the chief difference being that they lack the secondary cusps found in C. arxguineus 

 on either side of the main cusp. They definitely belong to a species apart from the next. 



C. A?iGUl7<lEUS. — The present'day species, the subject of this paper and of others 

 to follow, is usually accepted as the lowest living member of the great group Elasmo' 

 branchii. The external characters of this fish are dealt with throughout our paper 

 in extenso, and for that reason it seems best to quote Carman's brief characteriza-tion 

 (1913), inserting some corrections based on our studies: 



Body long, slender, subcylindrical, compressed behind the vent, which is behind the 

 middle of the total length. Head broad, wider than high, slightly convex. Snout broadly 

 rounded, hardly extending beyond the jaws. Nostrils lateral, behind the forward end of the 

 mouth. Eye rather large, elongate, about midway from eye [sic — angle of jaw?] to end of snout, 

 near a vertical from the mid-length of the mouth. Spiracle very small, distance behind the eye 

 about equal to distance from eye to end of snout. Mouth very large, extending as far back' 

 ward as the skull [cranium] ; upper and lower jaws of equal length. No labial folds. Teeth 

 small, similar in both jaws, several of each row in function; each tooth with three long, 

 slender, curved, backward directed cusps. A small cusp at [each side of] the base of the 

 middle cusp is not always [?] present. Bases of teeth broad, each with two prongs reaching 

 backward beneath the base of the next tooth in the row. Upper jaw with [approximately] 

 fourteen rows on each side, no median row. A median row on the symphysis of the lower jaws 

 [jaw] with [approximately] thirteen rows on each side of it. Pterygoquadrate attached to the 

 skull [cranium] in front of the postorbital process, between the eyes. Gill openings six, very 

 wide, oblique [?], in front of the pectorals; those of the two sides narrowly separated on 

 the isthmus, which is crossed by the free margins of the first gill cover. 



Pectorals moderate, broad, rounded. Dorsal small, base opposite and shorter than that 

 of anal. Anal larger than ventrals, tip reaching origin of caudal. Caudal long, pointed, armed 

 on upper edge by modified scales, subcaudal deep anteriorly, narrowing backward, not 

 [often] separated by a notch from the tip. 



Uniform [?] brown [darker on dorsum and on margins of fins]. 



