30 Bulletin 47, Uniifd States National Museum. 



This genus is verj' close to Mustrltis, with which it agrees iu most ex- 

 ternal respects, the essential difference being in the presence of a placenta 

 connecting the embryo with the uterus. The teeth are rather sharper 

 than in Mufitclns. The boundaries of this group and the preceding are 

 not yet well defined, and it may be that the two should be reunited. 

 (>«/ito(;, a kind of shark, like yaA?/, the weasel.) 



(I. Midilli^ ot first dorsal about midway between posterior root of pectorals and anterior root 

 of veutrals; first dorsal longer than higli ; its tip not reacliing tip of posterior lobe, its free 

 margin scarcely incised, its base about half the interval between dorsals; teeth sharpish. 

 (Knibryo not examined.) dorsalis, 32. 



aa. Midille of fir.ft dorsal much nearer root of ventrals than pectorals; snout rather short, its 

 length from mouth a little less than distance between angles of mouth; teeth rather 

 sharp. CALiFOUNicus, 33. 



32. «.iLEUS DORSALIS, (Gill). 



Lower lobe of caudal not acute; tail less than |^ total length, its terminal 

 lobe less than i its length; pectorals obtuse, their free edges almost 

 straight, their tij)S reaching first fourth of dorsal ; inner lobe of ventrals 

 not produced, the free edge of the fin straight. Embryo with placenta. 

 Color dark gray, axils of pectorals and ventrals dusky. L. 3 to 4 feet. 

 Panama and neighboring waters, north to the Gulf of California, the 

 largest species of the group, (dorsalis, pertaining to the back.) 



3/hkMhs (?o)-su?(,s-, Gn,l,, I'roc. Ac. Nat. Sci. Phila., 1804, 149, Panama. 

 Miustehts dorsalis, Jordan & Gilbert, Proc. U. S. Nat. Mus., 1882, 110. 



33. GALEUS CALIFORXICUS, (Gill). 



First dorsal longer than high, its blunt tip when depressed not reaching 

 tip of posterior lobe, its margin deeply incised, its base 2i times in the 

 interval between dorsals ; lower lobe of caudal blunt ; terminal lobe of 

 tail more than ^ its length, pectorals rather obtuse, their free margin 

 Utile concave, their tips reaching little jjast front of dorsal ; inner lobe of 

 ventrals somewhat produced ; embryo attached to uterus by a jdacenta. 

 Dark grayish ; axils of pectorals and ventrals dusky. L. 30 inches. Cali- 

 fornia, north to San Francisco; rather common. 



Mttstehts californicus, GiLL, Proc. Ac. Nat. Sci. Phila., 1864, 148, San Francisco. 

 Mustehts cdUforniais, .Jordan A Gilbert, Proc. IT. S. Nat. Mus., 1882, 110. 

 Mustelus californicus, Jordan & Gilbert, Synopsis, 870, 1883. 



20. RHINOTRIACIS, Gill. 



Hhinotriacis, Gill, Proc. Ac. Nat. Sci. Phila., 18C2, 4S(i, (henlei). 



General appearance of Galeus, but with the teeth distinctly tricuspid 

 and not paved. Snout sharp. Embryo attached to the uterus by a 

 placenta. Coloration plain. One species known. {()iv, snout; Triads). 



they have been accepted by nearly all later authors. It seeras to us best in cases like this to 

 follow the rules of nomenclature strictly. The strict letter of the law seems to require the use 

 of G'llcns in place of J'lem-ucrnmylon. 



The name MnsleJm was at first api)lied by Ouvier to the whole group of smooth-mouthed 

 sharks. It has, however, been restricted liy Gill to the subgenus tvpified by J)f. emus and >' 

 should be retained for this subdivision, leaving Pleuracromijlon, or Galeus, as'the name of the 

 Other genus or subgenus. 



