DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 21 



In tbe Mediterranean it is found at considerable deptlis. In July, 1S79, Prof. Giglioli, 

 Hsliing off Genoa with trawl lines, took 50 individuals at depths of 400 to 500 fatlioms. 



PRISTIURUS ATLANTICUS, Vaillant. (Figure 20.) 



T'riKihinis allanticits, Vaii.i.ant, Hxp. Sclent. Trav. et Tal., 1888, .59, ])1. i, fi;;. 1. 



A Pristiiirus closely resembling P. melafitomus, liatinesi|ue, bat with its snout some- 

 what more obtuse, its length t'lom the extremity of the upper lip being less than the dis- 

 tance between the labial commissures, while in the other species it is equal or greater. The 

 teeth are somewhat stouter, less elongate, and on their sides are two deuticulations instead 

 of the single one. Tliey also appear to be more numerous — 31 on each side of the upper 

 jaw, in i)lace of 28 in P. melanostomus. The cutaneous plates, although similar in character 

 and very like in form, liave the margin proportionately narrower, and the middle rib more 

 narrow and salient, the lateral teeth being less divergent. Tlie branchial openings decrease 

 in width i)osteriorly, tlie last not more than half the height of the first; while in F. melanos- 

 tomns it is at least three-fourths. 



The above description is a translation of the description by Yaillaut, who, though 

 admitting that the differences taken singly are slight, considered that taken together they 

 impart to the animal a peculiar physiognomy, and that the comparison of a number of 

 specimens of the same size seemed to him to justify the establishment of a new species. 



Vaillant is of the opinion that possibly this form may be that described by Lowe from 

 Madeira, under the name rristiurm mdanostomus. 



A single female, 440 millimeters in length, was taken at a depth of 540 meters ofi' Cape 

 Spartel, from Station viii of the French expedition. 



Family CETORHINID^^. 



Cetorhinidw, Gill, Arr. Fain. Fish., 1872, 24. — .Iokdan and (iILBEut, Bull, xvi, U. S. Nat. Mas., 1883, 30. 



Selachians with very wide gill openings in advance of pectorals, extending from the 

 back nearly to the midiUe line of tlie throat. Mouth moderate, the teeth small, numerous, con- 

 ical. Nictitating membrane lacking. A small spiracle between eye and first gill opening. 

 First dorsal large, above space between pectorals and ventrals ; second dorsal and anal 

 small. Pectorals and ventrals large. Caudal fin lunate, a pit at its root, the upper lobe 

 considerably the larger. Sides of tail keeled. 



CETORHINUS, Blainville. 



Ccloihiniis, Blainville, Bull. Soc. Philom., 1816, 121. 

 Selache, Cuvier, Eegne Animal, 1829, 390. 

 PuIyproso})us, COL'CH, Brit. Fish.. I. G7-68, pi. XV. 



Bye destitute of membrana nictitaus ; a small spiracle between the eye and the first 

 gill opening. Gill openings v(ny large. Gills furnished witli gill lakers for filtering pur- 

 poses, and consisting of an elastic apparatus of dentine. Teeth small, conical, without 

 dilated bases, and their sides smooth. First dorsal fin above the interspace between the 

 pectoral and ventral; second dorsal and anal small. Caudal with a lower lobe and a pit at 

 its root; sides of the tail keeled. (Day.) 



CETORHINUS MAXIMUS, Gunnek. (Figure 17.) 



Sqiialits iiiaximiis, Urx.VER. Tromllij. Selsk. Skrift., 1765, iii, 33, pi. ii, iv, U, pi. in. — LiXN.Ers, Syst. Nat., e<l. 

 XII, 1766, 400. 



Selache maxima, Cuvier, Regno Animal, 1829, 391. — Muller and Henle, S. B. Plagiost., 71. — Dum^ril, 

 Elasm., 143. — GOntiier, Cat. Fish. Brit. Mus., viii, 394. — Bocage and Capello, Peix. Plagiost., 14. — 

 Cetorhimis maximus, GooDE and Bean, Bull. Essex Inst., xi, 29. — Gioi.ioli. Elenco, 1883, 112. — Jordan 

 and Gilbert. Bull, xvi, U. S. Nat. Mus., 31.— Dav, Fish. G. B. & Ireland, ii, 303, pi. CLViii, fig. 1. 



Squalus elephas, Le Sieir, .Journ. Acad. Nat. Sci. Phila., ii, 343, fig. — Dk Kay, Zotil. N. V., Fish., 357, pi. 

 LXiii, fig. 208. 



