542 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The stem, though practically cylindrical, nevertheless increases 
somewhat in diameter toward the ends, the narrowest part being 
nearer to the body than to the base. 
Mantle thin, with distinct muscle bands which are neither very 
numerous nor closely placed. Radial and circular bands about the 
Text-fig. 28. — Culeolus suhmi Herdman. X 2. 
apertures rather poorly developed, the most conspicuous muscles 
being somewhat irregular bands crossing the ventral region trans- 
versely. 
Large tentacles twice compound, the branchlets few in number 
and somewhat pointed at the tip. There are ten or twelve of the 
largest tentacles and about an equal number of second-order tentacles 
alternating with them. Third-order tentacles (simply branched) 
appear to be present only in some of the intervals; still smaller ones 
if present are few and inconspicuous. 
Dorsal tubercle (distinguished in only one specimen) small and 
rounded, though prominent, with a simple pit-like aperture. 
Dorsal lamina broken up into a series of large leaf-like languets 
corresponding in number to the transverse vessels. They arise 
irregularly, with their broad surfaces transverse, oblique, or occasion- 
ally even almost parallel to the course of the median dorsal vessel. 
Branchial sac with six folds on each side, very delicate, consisting 
only of transverse vessels and internal longitudinal vessels. The 
transverse vessels are apparently about forty in number in the largest 
specimens, and except for a few short irregular smaller vessels here 
and there, are all of one order. The internal longitudinal vessels 
generally are so spaced that they form square or nearly square meshes 
on the interspaces between folds ; on the folds they are closer. They 
present nothing peculiar in their appearance or distribution, which 
