470 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Branchial sac of very delicate structure with six fairly prominent 
folds on each side, each of which bears a row of well developed in- 
fundibula, six in number. These are separated by the five principal 
transverse vessels, and each divides more or less completely into an 
anterior and a posterior apex separated by a short transverse vessel 
of the second order confined to the summit of the fold. The internal 
longitudinal vessels are confined to the folds. In a fairly large 
individual their total number was as follows: 
vidv. (7) (8) (7) (6) (5) (4) en. 
In the respects just described the branchial sac resembles that 
of our other species of Caesira, but in the arrangement of the stigmata 
there is in this species an approach to the condition prevailing in the 
genus Eugyra and in young specimens of the genus Bostrichobranchus. 
As in those genera, the spirals in alternate vertical columns of infun- 
dibula have opposite directions, and the free ends of the spirals 
terminate near the odd-numbered principal transverse vessels (nos. 
1, 3, and 5). The two spirals on the two apices of an infundibulum 
often, if not regularly, have opposite directions of twist. A very few 
slender radial vessels strengthen the infundibula, crossing without 
interrupting the stigmata. 
Intestinal loop fairly widely open for some distance from its reflected 
end. The whole loop is much less bent than in many of the other 
New England species, the reflected part being only slightly turned 
up toward the dorsal side of the body. Stomach wall with rather 
numerous irregular glandular folds. 
Kidney rather small, sausage-shaped, and only moderately wide. 
It has an oblique position against the body wall in the right posterior 
ventral part of the body. 
The gonads, which have the usual positions dorsal to the intestinal 
loop and the kidney respectively, are unusually wide and short. 
Each consists of a central flask-shaped ovary (containing in all the 
specimens studied very numerous small eggs) bordered, except at and 
near the small open end, with the numerous small lobed or pyriform 
testes. 
This species, readily distinguished by the fine moss-like processes 
on the outer surface and by the long spirally arranged stigmata and 
the short, broad, gonads, seems to be confined to moderately deep 
water (67 to 142^ fathoms) off the coast of southern New England 
