ON THE ANATOMY OF FISHES. 
189 
contracted proximally and expanded distally, and lias its long axis disposed at right 
angles to the axis of the body (fig. 78). Except at its root, which is nearly fiat, the 
transverse process of the fourth vertebra has the anterior margin curved down- 
wards towards the ventral surface, and of this decurved portion the mesial part is 
prolonged backwards as a somewhat triangular lamina of bone to form a partial 
floor for the osseous funnel. Near the flat root of the process the decurved 
anterior margin abruptly ceases, and leaves a cleft between its free inner edge 
and the lateral surface of the complex centrum, through which the tripus passes 
backwards from its connection with the scaphiura to gain the interior of 
the funnel. The posterior margin of the process is but slightly decurved except 
at its outer extremity, where a slender process of bone curves downwards, and 
forms tlie posterior lip of the distal aperture of the funnel. The transverse process of 
the fifth vertebra is comparatively slender, with a flat root and an anterior 
margin which is suturally united to the posterior edge of the preceding process in the 
roof of the bony funnel. The distal half of the process, however, has its hinder 
margin bent downwards and also a little forwards, to meet the recurved anterior edge 
of the preceding transverse process in the floor of the funnel, and finally ends in 
a somewhat irregular indentated edge. In this way the transverse process of the 
fourth vertebra furnishes the anterior and dorsal walls of the funnel and a partial floor, 
and, in addition, the posterior lip of its terminal aperture, while the corresponding 
process of the fifth vertebra forms the incomplete posterior wall. So far as the trans- 
verse processes are concerned, the bony walls of each funnel are incomplete, both 
proximally and distally, on the ventral and posterior surfaces ; proximally, however, 
the floor is to some extent completed by a thin, flattened, and tapering process of 
bone {v.p.), which grows out from each of the two lateral ridges bounding the median 
aortic groove in the region of the complex centrum, and extends outwards to the 
point where the recurved margins of the two transverse processes nearly meet in the 
floor of the funnel. This process is clearly the greatly enlarged representative of the 
ventral process of Bagarius and Glyptosternum, to wdiich attention has already been 
directed. Immediately behind the origin of these processes the two lateral aortic 
ridges are deeply emarginate, to admit of the passage of the median and tubular 
portion of the air-bladder across the ventral surface of the complex centrum from one 
lateral air-sac to the other. The anterior margin of the flat root of the transverse 
process of the fourth vertebra may be traced forwards along the external surface of 
the neural arch of the complex vertebra in the form of a longitudinal ridge, which 
finally ceases near the upper lip of the external atrial aperture. A somewhat similar, 
but more extensive, ridge (/.?’.), apparently a local thickening of the superficial ossifi- 
cations of the complex centrum, may also be traced from the lower lip of the atrial 
aperture obliquely backwards and upwards along the side of the centrum, where it is 
situated ventrad to the j)revious ridge, and then curves outwards across the ventral 
surface of the root of tiie transverse process of the fourth vertebra, ultimately dying 
