1873.] 351 [Morse. 
and likewise tipped the clusters therein contained, only these clusters 
were not supported on long threads, as in those which sprang from 
the genital band in the perivisceral cavity. The glandular portion 
of the segmental organ in the male appeared much darker than in 
the female. As Rhynchonella presents similar features in the ovaries 
contained in the pallial sinuses, we believe that the spermaries will be 
found in like positions. 
In this connection we must also consider the accessory vescicles of Huxley 
(accessory hearts of Hancock). After careful study of these minute organs 
from a large number of living specimens, I am convinced that they do not bear 
Hancock’s interpretation, and that they properly belong to the genital system 
and not to the circulatory system as stated by him. Hancock describes the 
walls of the “‘accessory hearts’? as more delicate than the walls of what he 
regards as the central dorsal heart. This is certainly not so in regard to Tere- 
bratulina. In J. septentrionalis, the organ presents all the appearance of a 
gland. The walls are thick and glandular, in fact, no sure evidence of a cavity 
within has yet been met with. It is irregularly pyriform in shape, slightly flat- 
tened, and in some is attached by a very constricted neck to the genital band 
just beneath the flaring margin of the mouth of the segmental organ. 
The exterior wall is made up of prominent transparent cells; at the base of 
the gland, and also on its walls, masses of yellowish granules in patches appear. 
On the genital band also I have seen irregular masses of cells, presenting all the 
appearances of the accessory vescicle. Repeated observations failed to detect 
any vascular communication with the band to which itis attached, not the 
slightest trace of circulation within its walls has been observed, nor the slightest 
evidences of dilatation or contraction, nor evidence of muscular fibre. I have 
repeatedly crushed it beneath the compressor, yet no signs of forcing out con- 
tents has been observed. Moreover the organ differed in appearance in different 
specimens, and even differed in appearance in the same individual upon the 
right and left sides of the body. With the idea at first that the sexes were 
united in Terebratulina, I was inclined to regard them as the testes, since they 
always occur in the immediate vicinity of the segmental organs. 
Where a single pair of segmental organs occur, as in Terebratulina, two 
accessory vescicles occur, one to each segmental organ. Where two pair occur 
as in Rhynchonella, four accessory vescicles are found likewise; one accom- 
panying each segmental organ. In Lingula, and Discina, though the segmental 
organs are large and conspicuous, and their study rendered comparatively easy, 
yet in no case has the accessory vescicle been met with. So far as we know 
then, the accessory vescicle occurs in Rhynchonellida and Terebratulide, or in 
those groups with the dorsal and ventral plates interlocking, which have no 
anus, and in which the ovaries are contained in the vascular sinuses of the 
pallial membrane. The accessory vescicles do not occur in Lingulidee or Dis- 
cinide, or in those groups having the dorsal and ventral plates free, possessing 
an anal outlet, and which have the ovaries entirely free in the perivisceral 
cavity. That they have nothing to do with the circulation is evident from the 
