STRUCTURES OF CHIMAEROIDS IOI 
the upper jaw (‘“premaxillary”’ and “ palatine’’) ; they are 
studded with hardened points, or “tritors”’ (Figs. 109-112). 
The sense organs are similar to those of sharks ; the nasal 
- capsule, VAS, has both an anterior and a posterior open- 
ing, O, O', the latter within the cavity of the mouth. 
The visceral parts are decidedly shark-like; the diges- 
tive tube is straight (p. 263) ; the intestine, /, with a spiral 
valve of three turns; the liver, Z, is prominent; the 
kidney, A, reproductive organs, 7, and their ducts, VD, 
SS, VS, and abdominal pores are as in sharks; the intes- 
tine, however, opens directly to the surface, A, separating 
an anal from a urogenital aperture, VG. The mesenteries 
are string-like. 
The male fish is provided with a highly specialized intro- 
mittent organ, CZ; it has a supplemental clasping organ, 
VC, at the front margin of each ventral fin, V (cf. also Fig. 
116 and Fig. 1162), and a retractile spine in the region of 
the forehead, 17SP (cf. Figs. 113 and 115). 
The skeleton of a Chimezeroid is shown in the following 
figure (Fig. 105). Its structure is cartilaginous. The ver- 
tebral axis is notochordal; its sheath, lacking in definite 
centra, is strengthened anteriorly by a series of calcified 
rings. In the anterior region of the trunk, neural proc- 
esses, interneurals, and neural spines, VP, JN, WS, to- 
gether with hzmal processes, occur as in sharks; toward 
the tail region they fade away, and before joining with 
the head at the occipital condyles, OC, they fuse into a 
compact mass, joining with the basa] supports of the 
dorsal fin. 
The cranium is of a highly compacted structure ; its 
vertical height has been greatly produced ; the orbits, OR, 
are of great size and are separated from each other by a 
membranous septum. The snout region is greatly meta- 
