MUSEUM OF COMPAKATIVE ZOOLOGY. 87 



their tubules, as those of the occipitals, start out, but turn and cross the tubes 

 toward the middle. Opposite the fontanelle the cranials make a broad open 

 bend, from which the short rostrals pass about half-way to the middle of the 

 mouth. From the front end of the rostrals the subrostrals turn back, around 

 and behind the nostril, to meet the nasals on the sides of the face. The pre- 

 nasals lie. on the upper surface ; they are nearly transverse, and turn back at 

 the ends as if to join the rostrals, but without making a junction. Apparently 

 the very short median is vertical. The orbitals are entirely on the upper sur- 

 face. From the cranials, they go obliquely outward until past the orbit, then, 

 turning forward at a right angle, the suborbitals run a short distance beyond 

 the eye, where they turn out and backward, making a deep loop, convex in 

 front. They meet the angular opposite the eye. Both angular and jugular 

 are on the top of the disk. The orbito-nasal is on the side of the face; it is 

 comparatively elongate, running from opposite the middle of the orbit to 

 within a short distance of the nostril. The orals and the nasals belong to 

 the lower view. The former are elongate, disconnected, and do not reach the 

 symphysis; the latter are moderate and transverse, with a shallow curve for- 

 ward toward the middle. The tubules from the suborbitals are rather long 

 and pass outward; they, like the others, are unbranched. 



The appearance of all the tubes, except orals and nasals, on the top, looks 

 as if resultant from depression that had caused great expansion of the ven- 

 tral portions of the body, and but little of the dorsal. This peculiarity alone 

 would serve to distinguish the genus from the other genera. There is nothing 

 in the canal system that favors the idea of close affinity with the Batoidei. 



Pristiophorus. 



Considerable uncertainty exists in connection with several points on the 

 sketch of Pristiophorus cirratus (Plate XXII.), because of the bad condition 

 of the specimen, a dried skin. 



Back of the head the laterals turn outward somewhat; on the tail they 

 appear to lie near the middle of the muscular portion, stopping at the end of 

 the column. 



The halves of the aural meet in a sharp angle at the middle; behind the 

 openings of the aqueducts they form a V, from the apex of which a short 

 tube extends directly back. A low inward sweep is made b) r the cranials, on 

 the crown. Beneath the eye the orbital does not quite reach the front edge 

 of the orbit; turning backward, it descends to join the angular on a vertical 

 from the centre of the pupil. The angular is longer than the jugular. Ap- 

 parently there is no oral. The orbito-nasal is rather long; and. with the 

 angular and the subrostral, it forms a longitudinal line. In front of the mouth 

 the nasal is turned back; it has a moderate nasal curve, and does not connect 

 with its fellow to form a median. Prenasals and subrostrals are very long. In 

 the specimen they cannot be followed near the end of the rostrum. 



There are marked resemblances between this Shark and Acanthias, which 



