similarities such as the development of long, very 

 slender nasal flaps in species of each genus {H. 

 bivius and S. tenuis), the relatively short caudal 

 lobes in combination with long postpelvic trunk in 

 both groups, and certain somewhat subtle similari- 

 ties in denticle structure. 



Problems in connection with names to be ap- 

 plied to South American Halaelurus cannot be ade- 

 quately treated here because of insufficient study 

 material. My view that more species than Hala- 

 elurus chilensis (Guichenot, 1847) and HalaeVwrus 

 bivius (Muller and and Henle, 1841) are involved 

 in the material described by various authors has 

 been strengthened by discussions with Dr. Sic- 

 cardi. 



Some unresolved questions on the status of types 

 add to the difficulties with nomenclature. The 

 types of both H. bivius and H. chilensis are stuffed 

 specimens. The specimen designated as the type 

 of bivius by Giinther (1870) is said to be from 

 southwest. Africa but Gunther's description is not 

 in close agreement with the earlier description of 

 Muller and Henle (1841). The confusing synon- 

 omy of bivius can be seen in the treatment given 

 in Norman's work (1937) on Patagonian fishes. 



It seems probable that all of the accounts of 

 South American Halaelurus, including this one, 

 have been based on material quite inadequate to 

 delineate species. Available material suggests 

 that considerable differences in some characters 

 may exist between young and adults of the same 

 species. This makes the development of meaning- 

 ful synonymy impractical. It is possible that 

 both Berg (1895) and Lahille (1921, 1928) dis- 

 cussed the form here referred to H. chilensis under 

 the name bivium or bivius. Vaillant's account 

 (1891), under Scyllium chilense Guichenot, states 

 that he believes Scyllium bivhim Smith is not a 

 distinct species, but goes on to state that all the 

 small examples he had seen were females. 



A more extensive study of these scyliorhinids 

 should provide some answers of great interest to 

 the phylogeny of carcharhinid sharks because 

 these sharks, perhaps considered together with 

 Schroederirhlhi/s, have more characters approach- 

 ing the carcharhinid line than do other scylior- 

 hinids. The longer jaw of H. bivius together 

 with lower jaw spikelike teeth is a feature more 

 familiar in the Carcharhinidae than in the Scylior- 

 hinidae. The claspers and clasper siphons of 



Schroederichthys bear many resemblances to those 

 of the carcharhinids. 



Halaelurus bivius (Muller and Henle), 1841 



Figure 26; tables 7 and 8. 



The specimens of H. bivius from Chile examined 

 for this report are very easily separated from 

 Chilean examples of H. chilensis by differences in 

 general shape. As can be seen in the photographs 

 (fig. 26), H. chilensis has a shorter head, a some- 

 what shorter and definitely less pointed snout, and 

 a shorter and much less strongly arched jaw. 



The specimens of H. chilensis examined were im- 

 mature, showing a well-marked series of enlarged 

 denticles in rows along the back, and in this dif- 

 fered from the adult H. bivius available for com- 

 parison. The specimens of H. bivius, however, 

 had some enlarged dorsolateral denticles. 



In direct comparison of H. bivius with H. chU- 

 ensis specimens, it was noted that the nasal flaps 

 of H. bivius were longer and narrower, the gill 

 slits were somewhat longer, the anal fin base was 

 somewhat longer (see table 7 and 8) , and the denti- 

 cles prevalent on dorsolateral surfaces had longer 

 points. 



Halaelurus chilensis (Guichenot), 1847 



Figure 26 ; tables 7 and 8. 



Based on specimens from the Pacific coast of 

 South America, it appears that there are relatively 

 great differences between H. chilensis and H. , 

 bivius. It should be noted, however, that all of 

 the specimens of H. bivius seen were adult males 

 while all the specimens referred to H. chilensis 

 were immature. 



SUMMARY AND COMMENT 



To have accomplished its purpose, this study 

 should have indicated some of the kinds of infor- 

 mation about catsharks needed for an adequate 

 revision of the family. Great variation within 

 species, particularly in morphometries, the occur- 

 rence of sexual dimorphism (at least in one 

 species) , and the finding of a new genus and several 

 new species point to the need for more comprehen- 

 sive collections from the continental slopes and 

 from ocean basins as a basis for understanding 

 the group. 



Western Atlantic scyliorhinids all have been 

 taken at depths where relatively cool temperatures 

 prevail ; and in the course of a more general study 

 of the group, if will be interesting to note which, 



618 



U.S. FISH AND WILDLIFE SERVICE 



