No specimens from the coast of Argentina were 

 seen. Halaelurus Mvius (Smith) has been re- 

 corded from Argentina by Berg (1895), Lahille 

 (1921, 1928), and Norman (1937). Halaelurus 

 chUensis (Guichenot) mentioned by Lahille 

 (1928) as a synonym of Halaelurus Mvius 

 (Smith) probably is a valid species and two spe- 

 cies referrable to Halaelurus occur in Argentine 

 waters according to information received from 

 Professor Elvira M. Siccardi (personal communi- 

 cation). Professor Siccardi also found a popula- 

 tion of Scyliorhinus on the coast of Argentina, 

 either S. boa (Goode and Bean) or an undescribed 

 species very similar to S. boa. Species found on 

 the coast of Argentina are given very brief treat- 

 ment here, based chiefly on photographs, measure- 

 ments, and records of specimens that Professor 

 Siccardi has kindly allowed me to see. Illustra- 

 tions in this paper of Halaelurus are of specimens 

 from Chile in the collection of the U.S. National 

 Museum. 



Ideal study series, that is, series including adults 

 of both sexes, young in various states of growth, 

 and specimens collected from a number of locali- 

 ties sufficient to outline the probable limits of 

 geographical and vertical distribution, are not 

 available for any of the 15 species treated here. 

 For example : available specimens of ScyUorhinus 

 retifer (Garman) satisfy ideal requirements 

 except that no adult females with eggs have been 

 examined; the series of Apristurus riveri Bigelow 

 and Schroeder includes two adult males and three 

 adult females, one with a partly extruded egg case, 

 and a few young examples, material sufficient to 

 show sexual dimorphism in the teeth of the adults 

 and to show the oviparous habit, but the series 

 lacks immature males. 



Family SCYLIORHINIDAE 



The definition of the family given by Bigelow 

 and Schroeder (1948, pp. 195-196) is followed 

 provisionally. Separation of the cat sharks from 

 members of the family Orectolobidae on the basis 

 of external form is comparatively simple when 

 dealing witli American material. No Atlantic 

 American cat shark has barbels or has the nostrils 

 connected with the mouth by a groove, while 

 orectolobids in general have these characteristics. 

 One Indian ( )cean genus, C onoporodernia , referred 

 to Scyliorhinidae by Bigelow and Schroeder, has 

 barbels and another, HaploolepTuirus, does have 



the nostrils connected with the mouth by a groove. 

 Otherwise the use of these characters to separate 

 the Scyliorhinidae from the Orectolobidae is the 

 most practical one. Of the characters given by 

 Bigelow and Schroeder for separartion of the two 

 families, Orectolobidae and Scyliorhinidae (1948, 

 pp. 178 and 195), the only characterization of the 

 Scyliorhinidae always applicable is that the 

 scyliorhinids have three rostral cartilages, united 

 at their tips; whereas orectolobids have none, one, 

 or three rostral cartilages which are small and, if 

 present, are not united at their tips. I have veri- 

 fied this only in a few western Atlantic species. 

 Even tooth characters do not hold unless excep- 

 tions are noted. Adult males of Apristurus riveri 

 Bigelow and Schroeder, instead of having small 

 teeth with several cusps as in all other known 

 scyliorhinids including female ^4. riveri, have 

 single cusped teeth in about 20 median rows. 



Grace White (1936), commenting on forms 

 generally known as cat sharks, states that varia- 

 tion in the catuloids (cat sharks and allied groups) 

 is so extreme as to make the distinction even among 

 genera difficult. Certainly it is difficult to find 

 family characteristics to which there are no excep- 

 tions and which set off scyliorhinids sharply from 

 obviously related families. Although there has 

 been reasonably general agreement on the kinds of 

 sharks constituting the group known by the 

 common name cat shark, precise morphological 

 definitions of the family or families constituting 

 the cat sharks and their allies have been various 

 and apparently not entirely satisfactory even to 

 those proposing the definitions. The cat sharks 

 are, with few exceptions, small demersal forms of 

 moderately deep water, and, again with excep- 

 tions, are not well known and are poorly repre- 

 sented in study collections. It is not unlikely that 

 the group contains representatives of several evo- 

 lutionary lines and that at the family level most 

 of the classifications that have been proposed em- 

 brace horizontal groupings. 



Miiller and Henle (1841) placed all the sharks 

 known by them to be egg layers in the family 

 Scyllia, including both the scyliorhinids and the 

 orectolobids without making a distinction between 

 sharks in which egg cases are resorbed after for- 

 mation or are retained in the oviducts until hatch- 

 ing (ovoviviparous species) and forms that dis- 

 charge eggs in leathery cases at an early stage in 



,->N2 



U.S. FISH AND WILDLIFE SERVICE 



