316 
WILLIAM F. ALLEX. 
tlie embiToiiic trunk to be a single trunk that later divided’ 
in order to encircle a ray. At frequent intervals from either 
side numerous connecting branches are received from each of 
the lateral veno-lymphatic sinuses. Below and immediately 
behind the lateral processes of the median ventral cartilagi- 
nous bar this portion of the ventral trunk received the three 
terminal branches of the posterior or transverse portion of 
the longitudinal haemal lymphatic trunks (Figs. 2 and 4, 
L. Hse. T. (ij)^ which is a short vertical trunk formed by the 
posterior union of the two longitudinal hasmal lymphatic 
trunks. 
From this point caudad the remaining portion of the 
ventral lymphatic trunk can be designated as the posterior 
portion of the ventral trunk (Fig*. 4), or possibly as the 
caudal trunk from its similarity to the caudal lymphatic 
trunk of the Teleosts. This canal, situated immediately 
below the caudal hearts^ traverses the ventro-laterai border 
of the median ventral bar to its distal end, where it receives 
a large anastomosing branch from each lateral sinus. Like 
the anterior portion, it is a single trunk between two rays and 
paired in the region of the rays. It also receives many com- 
municating branches from the lateral sinuses. In the region 
of the anterior portion of the caudal hearts one or two 
branches (Figs. 1 and 4) are given off dorsad to communicate 
with each caudal heart, and each orifice is guarded by two 
valves opening' into the heart (Fig. 1, Veil, (i).) In the case 
of a heart receiving but one communication from the posterior 
portion of the ventral trunk, there was always noted in all 
specimens examined a ridge in the floor of the heart wdiere 
one would expect the posterior communication w4th the 
ventral trunk to occur; possibly this may represent fused 
valve-folds that had formally guarded an orifice of an 
embryonic ventral trunk communication. 
Longitudinal Htemal Lymphatic Trunks (Figs. 2,3,. 
4, and 4 a, L. Hse. T. or R. and L. Hse. T .). — ATithin the haemal 
canal there is a pair of large lymphatic canals situated on 
either side of the caudal artery and between the caudal artery 
