548 MR. T. GOODEY OX THE SKELETAL [Mar. 15, 



at right angles to the axial portion. The cartilages forming this 

 pair are fused in the median line, and are closely united by liga- 

 ment with the large posterior basi branchial. In another example 

 they are not fused with each other, but are closely and firmly 

 attached together by ligament (fig. 6). The fifth pair is repre- 

 sented by rather prominent lateral processes (hbr. 5) which lie 

 close to the anterior end of the large basibranchial. The sixth 

 pair is also represented by lateral processes, not so pronounced, 

 however, as the fifth pair. 



Ceratobranchials. — I have little to add here to Garman's 

 description, except to say that all — excluding the sixth — have a 

 forward bend at their lower extremities, which brings these parts 

 parallel with the median horizontal axis. The first and second 

 pairs are curiously expanded also in this region, having an almost 

 bilobate appearance. The posterior part of the expansion is 

 rounded and underlies the expanded part of the following hypo- 

 branchials. 



The sixth pair is very massive and on its anterior ventral 

 border each has a thin, almost wing-like portion, which Fiirbringer 

 considers as the representative of the branchial rays of this arch. 

 There is nothing of note in the epi- and pharyngo-branchials of 

 the first five arches. In the case of the sixth, however, it is 

 probable that only the epibranchial is present; the pharyngo- 

 branchial being perhaps incorporated with it. It has a peculiar 

 shape, quite different from the slender, tapering bar figured by 

 Garman. At its point of attachment to the distal end of the 

 ceratobranchial it has an irregular outline. It next narrows 

 somewhat, and then carries a small process on its inner concave 

 border. The outer edge is convex and the whole piece gradually 

 tapers to a rounded end, which is anteriorly and inwardly 

 directed. 



Seventh vestigial arch. — This is not present in the specimen which 

 serves for the description of most of this paper, unless it be that 

 it is represented by a pair of rather sharp ridges on the ventral 

 side of the last basibranchial at the proximal ends of the sixth 

 ceratobranchials. In the case, however, of the large female 

 specimen it is present, and takes the form of a pair of small seg- 

 mental, tapering pieces (v.b.a. 1) lying on the ventral side of the 

 last basibranchial at the bases of the sixth ceratobranchials. 



Each arch consists of two small pieces of cartilage united by 

 connective tissue fibres to the surrounding parts. The more 

 anterior portion in each is rather irregular in outline and on its 

 posterior border carries a second slender, tapering portion. 

 Fiirbringer (6), who was the first to describe this very interesting 

 vestige, merely speaks of it as a small piece of cartilage, and his 

 figure gives no adequate idea of its structure and disposition 

 relative to the surrounding parts. 



As a matter of fact, it is very variable in structure ; for that 

 described by Hawkes (17) was made up of four small pieces on 



