104 PROCEEDINGS OF THE ACADEMY OF [Feb., 



Tlie following four sections (figs. 6e-h) all pass through the 

 coiled posterior end of the gland, at the points indicated by the 

 corresponding letters in fig. 6k. The apparent complexity of these 

 four sections will be made plain by compaiing them with the dia- 

 grammatic lateral view^ of the gland (fig. 6^). In all four sections, 

 what we have called the lateral pairs of cell-groups (Leg.) remain 

 the same and may be recognized by their long, curved, lateral 

 ciliated chambers (l.c.h.). 



In fig. 6e the median pairs of cell-groups are seen in a mid- 

 ventral position (m.c.g.) as they are followed in an anterior-poste- 

 rior direction, again in a mid-dorsal position (m.c.g'.) as they are 

 followed in a posterior-anterior direction, and again in nearly the 

 centre of the gland at m.c.g". as they are followed toward the pos- 

 terior end again. This is easily understood by noting the position 

 of the line e in fig. 6^, which shows that the section is cut at the 

 point where the posterior-anteriorly directed part of the median 

 cell-groups (m.c.g'.) turns ventralward, to pass again toward the 

 posterior (m.c.g".). The central ciliated chamber (m.c.h.) is thus 

 seen, in this section, to be continuous from the dorsal (m.c.g'.) to 

 the middle (m.c.g". ) position of the median cell-groups. The gen- 

 eral character of the various groups and layers of cells remains 

 about the same in all four of these sections, so that it will be only 

 necessary to speak of their position and arrangement in the sections. 



The next section (fig. 6/. ) cuts the median cell -groups in four 

 places, as is shown in fig. (Sk — at m.c.g. in the antex'ior-posteriorly 

 directed portion, at?n.e.f/'. in the dorsal posterior-anterior portion, 

 at m.c.g". in the part that is directed again toward the 

 posterior end, and at m.c.g'". in the last whorl of ihe coil which is 

 directed toward the anterior end of the gland. It will be noticed 

 in this and in the other sections passing through the coiled part of 

 the gland, that the median lamella (m.l.) extends into the coil only 

 a short distance. It extends thi'ough the dorsally directed part of 

 the coil shown in fig. 6 A, and for a shoi't distance in the posterior- 

 anteriorly part lettered m.c.g'. Whether it was never found in 

 this end of the gland, oi whether it was flattened out by compres- 

 sion was not determined. The shape of the median ciliated cham- 

 ber varies considerably in the different whorls of the coil, as is seen 

 in fig. 6/, m.c.h. In its ventral position — that is, in the position 

 lettered m.c.g. — the ciliated chamber has the same outline as in pre- 



