162 CAUR1RNIA ACADEMY OF SCrENCI-:S 



Family TllIGLID.K. 



299. Prionotus xenisma Jordan iL- Bollman. 



nrctlgcd at Albatross Stations 2795 and 2805, in Paiinina Hay, 33 and 51 .\ 

 fatlionis; the types only known. 



300. Prionotus loxias Jordan. 



Only the types known; dredged at Albatross Station 2805, Panama Bay, 511 

 fathoms. 



301. Prionotus quiescens Jordan tt- Bollman. 



The types were dredged by the Albatross in Panama Bay, in depths of 7 to 

 511 fathoms. 



302. Prionotus albirostris Jordan d- Bollman. 

 The types from Albatross Station 2795, Panama Bay, 33 fathoms. 



303. Prionotus horrens Richardson. 



This species is very similar in general ap])earance to P. ruscarius, with which 

 it has been freqnently confnsed. The two agree in having a continuous sharp ridge 

 running from the margin of the snout across preorbital and cheek to the preoper- 

 cular spine, this ridge bearing several strong bramble-like spines standing out from 

 the head at right angles, and hooked backward. In this respect, both species diller 

 conspicuously from /-". trihnluA, in the adults of which the rostral spine, the spine on 

 the middle of preorbital, and that on the middle of cheek become inconspicuous or 

 wholly wanting. P. tribulus cannot be considered a representative Atlantic species of 

 either of these Pacific forms, for the relationship is not so close as has been assumed. 



P. horrens seems to be less abundant than P. ruscarius. We secured four 

 adults at Panama. Three others have been reported by Jordan and Bollman 

 (1889, p. 182) from Albatross Station 2800, in Panama Bay. Aside from these, the 

 species is known only from the Gulf of Fonseca, where the tyjies were obtained. 

 The following description is drawn from the seven specimens above noted: 



Head 2? to 2| in length to base of caudal; depth 4 to 4 J. Snout equaling maxillary, 2^ to 

 2^ in head; eye 5|^ to 6; interorbital width 4. Dorsal X, 11; anal 9. Snout depressed, the longi- 

 tudinal profile nearly straight, the sides concave, flaring strongly outwards to the sharp ridge at its 

 lower margin. Beneath the ridge, the surface of the preorbitals is horizontal, continuous with that of 

 the widely exposed dentigerous portion of the premaxillaries, and with the lower surface of the head. 

 The snout is squarely truncate, or the preorbitals, especially in the young, may project slightly beyond 

 its tip. They are never strongly produced, as in P. ruscarius, and permit a wide strip of the premax- 

 illaries to be seen from above in the closed mouth. 



The interorbital space is wide and flat, bounded by bluntly rounded supraocular ridges, which 

 are usually low, but vary somewhat. This space is never deeply concave, as in P. ruscarius and 

 P. tribulus. 



