244 BULLETIN OF THE BUREAU OF FISHERIES. 



<;, Nostrils cmifluotil with iiiimlU lin species included hcroiiiV with a nusoral groove and 



a cirrus on the uiilcrior nasal valve ; (irst dnrs;il alvivo vcntrals Oroctolohidse. 



gg. Nostrils nut oiitluont with the mouth (in species inohided hcrrinV cirri absent or 



nidinientarv; first dorsal l>ehiiul veiitrals ... .Catitlidic. 



re. Nictitating inenihrane present; sjiiracles absent or pres<-nt 



/i. Teeth niore or less conipros.sed , trianijnlar. one or two series functioning. 



i. Head normal, not expiuidcd acniss the orbital region Circharhinidoe. 



It. Head much expanded across orbiUil region, hammer-headed or kindney- 



shaped CcstraciontidsE. 



Iih. Teeth depressed, paved, several series functioning Galeorhinidoe. 



hh. Anal iin absent; tw^) dors;ils each with a spine; spiracles present; mouth protrusiblc, with a 



deep gnxi ve at each angle Squalidas. 



(Ki. Ilody and head depressed; no aital Iin; pectorals produced but free from the head; twx) spine- 

 less <lors;ils on (he tail Rhinidie. 



II. 1'i.aTosomia: Body disxxiid; pectorals alt.iched to the heail; gill ojieningson ventral surface of disk. 

 (I. Tail c^)niparatively thick, with tw) <lors;ils and a caudal tin; no serrated caudal spines. 

 h. Na.soral grooves absent; disk narrow and elongate; tail strong. 

 (■. Snout sawlikc. much produced. Hat, armed with stmng teeth on each .side, set at right angles 



to its axis; disk small; pectorals not continvied forward at side of head Pristida:. 



iX. Snout more or less produced, not s;iwlike, t(K)thless; disk moderate; pectorals continued at 



side of head, not reaching end of snout Rhinobatidx. 



hb. Nasoral grooves present; disk bn»^>d, rounded, or angular; tail moderate to .short. 



i/, Disk subeircnlar; .skin smooth; an electric battery at each side of head. . . .Narcaciontida!. 

 </(/. Pisk rhomboidal; skin usually nnigh, with spines or tubercles; no eleolrio batterj'. .Rajidte. 

 art. Tail slender, with one or no dors;d Iin and usvially w ilh one or more serrated siMnes. 



t. IVctoral tins uninterrupted, confluent aroimd the snout; teeth small; disk subeircnlar to 



rhoml>oidal D.isylMtida?. 



ee. Head bearing a pair of rostral or cephalic fins, representing a jvartly or entirely separated 

 section of the pectoral tins; disk very bnwd and angular, 

 /. Head bearing a pair of nxslral lins: teeth bnvul, molarial. 



g. A pair of rostral Inis joined in front of .snout, forming a single lobe Myliobatida!. 



gg. Snout in two separate lobes, the rxistr.d tins not joined in front of the skull imd not 



continuousat the sides of the head with the pectorals Rliinoptcrida;. 



//. Head beariitg a cephalic fin, a separate section of the pectorals, extended forward as a 

 hontlike process from each side; teeth small, numerous, in jwvemcnt. . . .Mobulida-. 



Family CARCH.\KIII).4'. The sand shaiks. 



G«nus CARCHARIAS Rafiuesque. 

 1. Carcharias taurus Rafiuesque. S:md shark; s.'ind-h.ir shark. 



Em^mf>k\tH.t litti^Ah}^, Yanvw, i.S??, p. ot?. 

 CarftntrM/t Amrtir^itns. }oT\iAn and Gilbert. iS^, p. 3S?. 



Ctuharias Itlhiralis. Jordan. i.^Sft, p. j*; Jenkins, tSSj, p. S4; Jordan and Evermnnn. 1S9S, p. jm8; Smith, 190?, p. 3:; Cud- 

 g«r, r9t,il>, p. »S; CoIm, iiju, p. «i. 



Tect*.— Teeth slender, in ^-^ ('*,,"*)'' rows; bases two-rooted, with one or twx) slender, shiup- 



planted denticles at each side of cusp; teeth in fmnt of mouth long, stibnlate, sinuate, slightly pr\itniditvg; 

 on Ujc sides of the jaws they arc graduated, the length and crxwkcdncss of median cusp diminishing, the 

 loor 13 rows ncatrst ai^glesof mouth being tricusjudatc. several rows at angles minute; teeth of lirst row- 

 in upper jaw slightly smaller titan the second; those of tlic fourth row in the upper jaw and Uic first row 

 in the U>wcr jaw much smaller; some of the tipjKr teeth have two small denticles on one or botli sides; 

 two rows of functioning teeth. 



" G«nnan. PI»siostomia. p. sj. 



