DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 473 



sion, is equal to the length of the head; the preorbital extension about two-fifths of the 

 length of the snout. The preorbital processes are flat, unarmed, and somewhal divergent : 

 a ridge arises at the base of the preorbital process and extends to the angle of the preoper 

 < - 1 1 1 1 1 1 1 1 . where it terminates in a blunt spine; a low ridge on the operculum, ending in a 

 rather inconspicuous spine; another above, and close t" it, pointing npward. The length 

 of the opercular ridge of spines is nearly equal to the horizontal diameter of the eye. 



Jaws feeble and apparentlj toothless; barbels on the lower jaw so inconspicuous at 

 present as to be scarcely visible. 



The maxillary extends almost to the vertical through the anterior margin of the eye; 

 the diameter of the eye is contained 1 times in the length of the bead without its pro 

 Ionizations. 



The dorsal origin is over the tip of the opercular spine; the origin of the anal apparently 

 behind that of t lie second dorsal; ventrals slightly in advance of the pectorals, and not so 

 tar back, though their tips reach somewhat beyond the vent; pectorals rather long; about 

 t\\ eiity five row s of scales. 



The type, about 2 inches in length, is in the Museum of Comparative Zoologj at 

 Cambridge, and has been studied in the preparation of this description, but the example 

 being unique and very small, we have nol ventured to examine it so closely as would have 

 been practicable with mine material. It is, however, apparently a well marked species. 

 resembling in a general way /'. longispatha. It was obtained by Poey from the stomach 

 of Polymixia noMlis, taken near Cuba in deep water. 



PERISTEDION GRACILE, Goode ami Bean, n. 8. (Figure 387). 



Body very slender; its greatest height (18 millimeters) is nearly one-sixth of its length. 

 The length of the head to the tip of the prolongated rostral spine is 48 millimeters; without 

 the prolongations its Iengthis36 millimeters or twice the greatest heightof the body. The 

 interorbital space is deeply concave. Theinterorbital width (10 millimeters) equals one half 

 the length ofthe snout including the rostral spine. The forehead descends gently towards 

 the snout and the supraorbital crests are very little elevated. The rostral spine on each 

 side is continued backward by a slight bony ridge ending in a blunt spine at the angle of 

 the preoperculum. The opercular spine is small, the length of the operculum with the 

 spine being about equal to the length of the eye. The length ofthe snout with preorbital 

 extension (29 mil li meters) is a little more than one-fourth of the standard length ; the length 

 of the spine alone (13 millimeters) is nearly equal to the length of the mandible. The jaws 

 are feeble and toothless. The length ofthe maxilla (12 millimeters) is one fourth the length 

 ofthe head. The length of the mandible (15 millimeters) is one-half the length of the 

 SnOUl with the preorbital extension. The mandible has two groups Of barbels, one on each 



side of its lower edge. The length of the longest barbel (0 millimeters) equals that of the 

 eye. The barbels are subdivided into several fringes; the number of barbels on each side 

 ofthe mandible may be divided up into 8 or 9 clusters. The mandible extends to the ver- 

 tical through the front ofthe eye. Twenty- six gill-raker s on the first arch, the longest one 

 half as Ion-' as the eye. The longitudinal diameter of the eye (9 millimeters) is nearly 

 equal to the width ofthe interorbital space. Greatest width of the head over the prcorbi 

 tal ridge (15 millimeters) is one half the length of the snout including the preorbital ex ten 

 sion. The spinous dorsal originates directly above the end of the opercular flap; the first 

 spine is slightly the longest, its length (15 millimeters) equals the length ofthe snout and 

 its projecting spine; it also equals the short diameter of the eye. The longest ray of the 

 second dorsal | 1 1 millimeters) is nearly one-fourth the length of t he head. The least height 

 of the tail (3 in il I i met ets) is one third the length of the eye. The anal origin is under the 

 second ray of the soft dorsal ; the fin extends as far back as the dorsal, the length of its 

 base (II millimeters) being I times the width of the interorbital area, the lays 

 about as long as those of the second dorsal. The length of the middle caudal rays (12 



millimeters) is four-thirds the length of the eye, the tin being emarginate. The ventral 

 base is under the pectoral base, the fin reaching to the vent, its length (18 millimeters) twice 



