MUSEUM OF COMPARATIVE ZOOLOGY. 19 
tomus has a very short bulbus and two rows, and Heterodontus francisce 
has three rows in a bulbus little if any more than half as long as the 
ventricle. Selache has three rows in a bulbus equally short (see Pavesi, 
Del Genere Selache, Pl. III, S. rostrata). A specimen of Somniosus 
microcephalus has a short bulbus and four rows of valves. 
Behind the ventricle, in the partition, between the peritoneum and the 
pericardium, there is a spongy mass of dark tissue an eighth of an inch 
in thickness. 
A Cardiac Parasite, Tetrarhynchus wardi, sp. n. 
The worm figured on Plate XVIII. figs. 8-10, was found within the 
cardiac chamber, attached to the lower side of the auricle, between it 
and the ventricle and bulbus. Dr. E. L. Mark, to whom it was sub- 
mitted, pronounces it a Tetrarhynchus, and thinks it possesses characters 
which will not admit of placing it in any of the described species of the 
genus. The head is large, subelliptical in transverse section, and sub- 
quadrangular or oblong in longitudinal outline. Against the scalpel or 
needle it is as hard as bone. The groove on each side extends back half 
the length of the head. When the hardened mucus is removed, the sur- 
face is seen to be covered with small papilla. Some of the teeth are 
much curved, forming arcs of ninety degrees; others are a little nearer 
straight. All seem to be compressed, and the base extends under the 
cusp or claw nearly the length of the latter. 
The slender portion, or tail, in a measure resembles the flattened tails 
of certain angle-worms. It does not show marks of division into seg- 
ments. Entrance into the cardiac chamber must have been effected when 
the worm was small, for at present the walls seem entirely closed against 
intruders. 
Being indebted to Professor Ward for our knowledge of it, we have 
taken the liberty of introducing the species in his name. 
Ovaries and Oviducts. 
Plate XIX. Fig. 1. 
Fortunately for us, when the captor tore the viscera from the speci- 
-men he left several important pieces. A section of some twelve inches 
in length of the ovaries and oviducts is represented in the sketch. The 
ovaries had been badly preserved and were much torn. Three inches 
from the anterior opening of one of the oviducts it bore a nidamental 
gland ; the gland of the other tube was an inch farther back. A piece 
