desirable treatment of other characters. Measure- 

 ments remain useful in description, but some bet- 

 ter balance and the use of a large number of char- 

 acters, including some that can best be described in 

 illustrations, seems desirable and perhaps neces- 

 sary for a revision of the family. 



KEY TO GENERA OF WESTERN ATLANTIC 

 SCYLIORHINIDAE 



The following key to western Atlantic genera 

 is sufficient for their separation, but the degree of 

 difference between them is better illustrated in 

 the chart given as table 2. 



KEY TO WESTERN ATLANTIC GENERA OF 

 SCYLIORHINIDAE 



1A. Color uniform lilaek or dark brown except for lighter 



or darker fins in some species Apristnrus 



IB. Color variegated with spots, blotches or saddles. 



lighter below 2A or 2B 



2A. Crest of enlarged denticles along upper edge of caudal 



fin Galeus 



2B. No crest of enlarged denticles along upper edge of 



caudal fin 3A or 3B 



3A. Tip of snout to anus about one-third of total 



length Schroederichthys 



3B. Tip of snout to anus about three-eighths to one-half 



of total length 4A or 4B 



4A. Labial fold present only along lower jaw 



Scyliorhinus 

 4B. Labial fold around corner of mouth extending along 



both jaws Halaelurus 



Genus Scyliorhinus Blainville 1816 

 Type species — Squalus canicula Lac£pede, designated 

 by Gill, 1861. 



Western Atlantic species of /Scyliorhinus differ 

 from one another primarily in color pattern al- 

 though one species, Scyliorhinus torrei, is much 

 smaller than the other four and another, S. meadi, 

 has more erect and slightly larger denticles than 

 any of the others, giving it a somewhat shaggy 

 appearance. 



Scyliorhinus t&razame (Tanaka) [ = Halaelurus 

 nulls (Pietchmann)] of Japanese waters, S. stel- 

 lar Is (Linnaeus) and S. canicula (Linnaeus) of 

 eastern North Atlantic waters, and S. capensls 

 (Miiller and Henle) of South Africa and the east- 

 ern Indian Ocean, all differ in details of color pat- 

 tern from one another and from American species. 

 No eastern Pacific species are known. Specimens 

 of S. torazams that have been examined have the 

 pelvic fins united to a point somewhat nearer their 

 tips than most specimens of the American species 

 and have enlarged and nearly erect dorsal denticles 

 rather regularly scattered on dorsal surfaces 

 among more numerous smaller ones ; but the larger 

 denticles are not arranged in rows, and the charac- 

 ter seems to be variable. The American species, 

 excepting S. torreL have slightly longer snouts 

 than other species. The European S. canicula has 

 the two nasal flaps united at the midline, and the 

 confluent flap reaches the edge of the upper lip. 

 As for other members of the genus, nasal flaps are 

 often smaller in examples of the American species 

 than in others, but specimens can be selected from 

 series of S. stellaris and S. retifer, for example, in 



Table 2. — Characteristics of genera of the family Scyliorhinidae as present in western Atlantic species 



Characters 



Scyliorhinus 



Halaelurus (shortest 

 snout) 



Galeus 



SchToederichthys 



Apristurus (longest 

 snout) 



Color. 



Caudal crest. 



Labial grooves 



Union of pelvic fins 

 posterior to anus. 



Enlarged dorsal 

 denticles. 



Claspers 



Clasper siphons. 

 Egg retention 



Sexual dimorphism in 

 tooth shape. 



Pores on snout 



Liver size in adults 



Variegated; dorsal sad- 

 dles present but 

 sometimes obscure. 



None 



Weak; present only on 



lower jaw. 

 About two-thirds 



united. 

 Present in embryos; 



and scars in very 



young. 

 Short; hooks weak or 



absent. 



Moderately short. 



Oviparous as far as 



known. 

 Not found 



Not prominent 



Large; posterior tips 

 usually reach as far 

 back as anal opening. 



As in Scyliorhinus. 



Strong on both jaws... 



Basal one-fourth to 

 one-half united. 



A few remain in some 

 adults. 



Not examined 



Not examined 



Oviparous as far as 



known. 

 Said to be present to 



slight degree. 



Not prominent. 

 Not examined... 



Plain color or variegated 

 but without well- 

 marked saddles. 



Present 



Moderate on both jaws.. 



Basal one-half to two- 

 thirds united. 



Few scars on very 

 young. 



Long; hooks present 



Moderately long 



Both oviparous and 



ovoviviparous species. 

 Not found 



Prominent 



Moderate; posterior tips 

 of liver lobes not 

 reaching as far back 

 as anus. 



As in ScyliOThinus. 



None. 



Moderate on both jaws. 

 No union 



Not found on material 

 available. 



Long; no hooks 



Long 



Oviparous as far as 



known (in 1 species). 

 Not found 



Not prominent 



Short; small; not ex- 

 tending appreciably 

 into posterior half of 

 body cavity. 



Black or sometimes 

 brown; color uniform 

 without strong mark- 

 ings. 



Absent except partly 

 developed in one 

 species. 



Strong on both jaws. 



Only trace of union. 

 Not found. 



Short; no hooks. 



Short. 



Oviparous as far as 

 known (in 2 species). 



Strong tooth dimorph- 

 ism in 1 species, not 

 in 3 others. 



Very prominent. 



Large; very long; tips 

 reaching posterior to 

 anus. 



REVIEW OF WESTERN ATLANTIC CAT SHARKS 



597 



