Spengelomenia. 469 
some parts of the duct has separated from the basal part. About 
midway between the pericardium and the shell gland are two small 
saceulations (Pl. 24, Fig. 12) that, since they contain spermatozoa, 
are probably seminai vesicles. It may be added that the sperms 
are not attached to the walls, but form a confused mass. 
At the point of union of the dorsal section of the gonoduct with 
the ventral limb or shell gland on each side two short diverticula 
appear that present different appearances and probably perform 
different functions. The more posterior sac is identieal with those 
just described and may be considered as a seminal vesicle, though 
like the one immediately in front it is empty. The anterior diver- 
ticulum is located in the usual position of a seminal receptacle, and 
furthermore resembles one in being attached to the shell gland by 
a short stalk, the opening into the expanded, distal portion being at 
the summit of a small papilla composed of slender columnar cells 
(Pl. 24, Fig. 11). 
The shell gland consists of two distinet elements, (a) a slender 
tube, of somewhat larger calibre than the dorsal limb, composed of 
cubical or low columnar cells between which great numbers of (b) 
pyriform gland cells pour their secretion. This ventral tube runs 
parallel with the dorsal section, but is nearer the median plane of 
the body, and by a union with its fellow forms an undivided section 
opening into the cloaca. The gland cells form a dense envelop about 
each ventral duct from the undivided portion to a point about half 
way to the seminal receptacles where they disappear from the outer 
surface of the duct, but continue to be attached to its inner face 
throughout the remainder of their course. These glandular elements 
form small groups or lobules, their delicate ductules pursuing a 
course of varying length to the coelomoduct. The secretion they 
contain almost completely fills each cell in the form of a finely 
granular, moderately staining substance that accordingly renders them 
distinguishable from the mass of gland cells adjacent to the cloacal 
walls. 
The terminal, undivided section of the coelomoducts is a simple 
tube, composed of slender columnar cells, that makes its way dorsally 
to open into the cloaca. Throughout its entire extent it is sur- 
rounded by a heavy sheath of ceircular muscles. As may be seen in 
Fig. 12, Pl. 24 the reproductive opening is borne on the summit of 
a great, flat-topped papilla whose muscular character and corrugated 
