Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. ^^ 



line, for nearly its entire length, the groove being widest and 

 deepest between those processes of the preorbital ossifications 

 that give articulation to the palato-quadrate. The ventral 

 edges of these latter articular processes are capped with thick 

 bands of cartilage, which extend outward, on each side, from the 

 ventral portion of the chondrocranium. Anteriorly the mid-ven- 

 tral groove becomes shallower, and finally disappears entirely 

 not far from the extreme anterior end of the chondrocranium. In 

 front of the anterior extremity of the groove there is a short and 

 narrow ungrooved surface, and then the chondrocranium ends 

 in a hooked or beak-like portion. 



The median longitudinal groove on the ventral surface of the 

 chondrocranium of the adult Salino is said by Parker to represent 

 the obtuse angle and space which, in earlier stages, lay between 

 the then unfused trabeculae (No. 50, p. 107). The trabecul^e 

 are said by him to arise, in Salmo, independently of each other 

 and of the "investing mass"; to fuse, later, wdth each other, and 

 with the anterior end of the investing mass ; and then, still later, 

 to become again separated from the latter mass. All of these 

 statements are confirmed by Stohr (No. 71, p. 97), but they are 

 not in accord with my interpretation of Vrolik's statement (No. 

 76, pp. 252, 254) that the " Schadelfalten" are outgrowths of the 

 "Schadelbalken." In the adult Saliiio the free hind end of each 

 of the trabeculae is said by Parker to present, on its ventral surface, 

 a facet, which is called by him the "anterior pterygoid process," 

 or posterior "facial connective growth." This facet or process 

 is said by him to be the basipterygoid of Huxley. The trabeculce 

 themselves are said by Parker to be the first facial arches 

 of the animal (No. 50, p. 114), a conclusion supported by Piatt's 

 recent work on Necturus (No. 56). 



The median groove on the ventral surface of the antorbital car- 

 tilage of Scomber lodges, throughout its entire length, a median, 

 longitudinal process, or rib, which rises vertically from the dorsal 

 surface of the parasphenoid, the latter bone itself fitting into a 

 larger, but slight depression only, in the same cartilage. Slightly 

 in front of the anterior end of this latter depression the chondro- 

 cranium ends in the hooked or beak-like portion already men- 

 tioned. The base of the beak is slightly wider than the cartilage 



