ESPECIALLY MYCTOPHOIDS 67 
whereas the anterior processes incline slightly forwards. Pleural ribs articulate 
with the apices of the larger pair of transverse processes. Some of the smaller, 
posterior transverse processes appear to have thin bones articulating with them, but 
these are more likely to be some of the numerous intermuscular bones. Posterior to 
the 26th precaudal vertebra both the pairs of transverse processes begin to decrease 
in length so that by the end of the precaudal region, at about the 50th vertebra, the 
processes are much reduced and project ventrally as opposed to their more normal 
ventro-lateral inclination. The anterior pair of transverse processes fuses in the mid- 
ventral line to produce the haemal arches ; this seems to have occurred on the 51st 
vertebra. From the postero-ventral part of this haemal arch a protuberance occurs 
which on the succeeding caudal vertebrae becomes elongated, forming curved haemal 
spines which attain their maximum length on the 4th caudal vertebra. As has been 
pointed out, the haemal spine arises from the posterior region of the haemal arch, 
while the anterior region of the haemal arch projects forwards very slightly on either 
side to form ventral prezygapophyses. The posterior transverse processes also 
incline ventrally in the caudal region but do not fuse together, merely forming 
ventral postzygapophyses. Throughout the caudal region the ventral pre- and post- 
zygapophyses are extremely prominent. The entire length of the dorsal surface of 
each centrum is occupied by an elongated neural arch which is a separate ossification 
to the centrum, the suture between the two structures being clearly visible. The 
neural arches are long and low and bear neural spines as projections from the extreme 
postero-dorsal region. The anterior region of each neural arch is produced on 
either side to give prezygapophyses. The corresponding postzygapophyses are found 
on the postero-dorsal part of the centrum, posterior to the base of the neural spine. 
The neural spines themselves are not particularly prominent, being short, straight 
and relatively narrow. 
Genus PELARGORHYNCQAUS von der Marck, 1858 
DiaGnosis (emended). Dercetidae in which both the skull and body are 
elongated. Premaxillae do not extend in front of the mesethmoid. Mandible 
extends to the anterior region of the snout. Maxilla enters the gape and is toothed. 
Paired fins reduced in size, pectorals being low on the flanks, pelvics arising below the 
anterior end of the dorsal fin. Dorsal fin occupies the posterior half of the back, 
anal fin short and remote. A single row of heart-shaped flank scutes along the 
lateral line, and a dense intermediate squamation of small rhomboidal scales covers 
the remainder of the body. 
TYPE SPECIES. Pelargorhynchus dercetiformis von der Marck. 
REMARKS. The genus was erected by von der Marck (1858) for the reception of 
several poorly preserved specimens from Sendenhorst, Westphalia. The genus is 
not recorded from any other localities. 
