470 Harorn Hear, 
walls suggest that in life it may, in the act of eopulation, be extended 
beyond the cloacal opening. | | 
Immediately behind the papilla bearing the reproductive opening 
the walls of the cloaca become developed into several large folds 
(Pl. 25 Fig. 16), filled with blood corpuscles, that thus probably serve 
as respiratory organs. Behind these, but not directly connected with 
them, is a slightly greater number of folds (Fig. 8), but in the 
present specimen they contain no blood corpuscles. A vast number 
of gland cells (Fig. 20), grouped into lobules, are situated in the 
visceral cavity between the posterior end of the pericardium and a 
point about level with the line I in Fig. 12, Pl. 24. They are more 
or less vacuolated and in a few cases appear to be pyriform (possibly 
due to pressure) but not a single, undoubted outlet for their secretion 
has been found. If they are not of the nature of plasma cells, 
related only to the blood streams in their midst, then their outlet is 
probably by intercellular channels into the cloacal chamber. 
The circulatory system may be dismissed with a few words 
only as it presents no especially noteworthy features. The peri- 
cardium is of unusual size, but in the present specimen the heart 
is highly contraeted and accordingly relativly small. As may be 
seen in Fig. 12 Pl. 24 the heart is free from the pericardial wall 
throughout the greater part of its course, and comprises two distinet 
divisions apparently guarded by a valve at the point of union. 
Into and out of the heart the blood follows the usual channels. 
The nervous system, even as regards its broader features, is 
difficult to follow, owing chiefly to the fact that where the nerves 
or ganglia crowd their way between the glands and other organs 
they become so compact that they assume the appearance of muscle 
fibres. The results obtained are represented in Pl. 24 from which it 
may be seen that, with few exceptions, this system is similar to 
that of several other solenogastres. T’he three pairs of nerves passing 
out from the forward surface of the brain are typically disposed 
and distributed; and the three pairs of connectives are likewise 
normal. The ventral cords are connected as usual by commissures, 
and on the other hand are united with the lateral ganglia by con- 
nectives. One unusual feature presents itself in the form of a strong 
nerve that springs from the anterior end of each lateral ganglion 
and after branching repeatedly is distributed to the body wall. It 
is possible that some of its delicate branches pass over to the ganglia 
about the bases of the eirri, but generally speaking its subdivisions 
