L 



II 



|CO 



\1 



5 mm 



I CO 



11 



I? 



IU5 



Figure 10. — Camera lucida outlines of teeth of 405-mm. 

 adult female Apristurus riveri (left) compared with 

 same scale outlines of teeth of 430-mm. adult male 



( right) both specimens from 860- to 914-ni. depth off the 

 Caribbean coast of Panama. 



changes in tooth form occur at sexual maturity or 

 whether several species with different tooth forms 

 are involved with or without changes during 

 growth. South American HaZaelurus (not in- 

 cluding the deeper water form ScyUhim eanescens 

 Giinther) shows a trend toward development of 

 spike dentition in the lower jaw. Spike teeth in 

 the lower jaw and cutting teeth in the upper jaw 

 always characterize species of the larger and more 

 specialized galeoids wherever differences in ap- 

 parent function between upper and lower jaws 

 exist. In contrast, in the notidanoids and squal- 

 oids it is the upper jaw that has spike teeth. 



It has been customary to express a tooth for- 

 mula for extant sharks simply as the number of 

 teetli in the upper jaw over the number of teeth 

 in the lower jaw. In sharks having only one 

 functional band of teeth, the counts are rather 

 easily determined. In C ' archarhinm leucos, for 

 example, this would be 27/25 where 27 is the num- 



ber of teeth on the upper jaw and 25 is the number 

 on the lower jaw. A refinement of this kind of 

 formula, used for example by Bigelow and 

 Schroeder (1948), breaks down the count to indi- 

 cate the number of very small teeth at or near the 

 jaw symphyses. In C. leucas such a count might 

 be expressed as 13 + 1 + 13/12 + 1 + 12, where 13 

 is the number of teeth on each side of the upper 

 jaw, 12 the number on each side of the lower jaw 

 and 1 represents the number of very small teeth at 

 the symphysis. Leriche (1905) developed a clas- 

 sification of the various types of teeth found in 

 the jaws of fossil sharks which permits the use of 

 a more descriptive and meaningful formula to ex- 

 press conditions found in various species. Apple- 

 gate (1965) has proposed some modification of the 

 Leriche system and an extension of its use to ex- 

 tant species. This system has obvious merits al- 

 though its formulas are perhaps less informative 

 about scyliorhinids than about, species in most 



REVIEW OF WESTERN ATLANTIC CAT SHARKS 



593 



