ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
671 
from the dorsal vessel of worms. Haller describes some other features, 
such as the nerve-plexus on the stomach, but they are of less interest. 
He reiterates his previous conclusion that the Aplaeopliora are divergent 
forms which have lost gills, shell, &c., and become adaptively worm-like, 
degenerate rather than primitive. 
8. Lamellibranchiata. 
Eyes of Cardium muticum.* — Mr. K. Kishinouye has discovered 
eyes in this mollusc which can be easily found without a Microscope, 
as black spots on the siphonal side of the tip of a tentacle. All the 
essential parts of an eye are to be found, and there is a general resem- 
blance to the eyes of Pecten, Spondylus , and Cardium edule. The cornea 
consists of thin pavement cells, and not, as in most Molluscs, of columnar 
cells. The lens is large, consists of a great number of cells, and is 
ovoid, not biconvex in form. The retina is in contact with and directly 
below the lens ; it is very simple in structure, being formed of one layer 
of columnar cells. The rods are directed away from the retinophores 
and are separated from them by a false membrane. Below this are 
layers which are called choroid and tapetum, and, lastly, there is a layer 
of pigmented cells. 
The eyes are innervated from the viscero-parietal ganglia, and they 
appear to develope in two ways ; both of these are abbreviated, but one 
is shorter than the other. 
Molluscoidea. 
a. Tunicata, 
Budding of Diplosomidae and Didemnidse.j — M. M. Cauilery lays 
emphasis upon the part which the epicardiac tubes play in the formation 
of buds. In Diplosoma gelatinosum Edw. these two tubes persist in the 
adult, separate from one another and from the branchial sac ; their upper 
*>nds extend to near the level of the stomach, at their lower end the heart 
lies ; their epithelium is in a state of continuous proliferation, except on 
the margin turned towards the interior of the intestinal loop. The 
author describes in detail how these two tubes take the chief share in 
forming the thoracic and abdominal buds, which fuse to form one indi- 
vidual. The interesting double origin is considered, thus the alimentary 
canal is formed from three independent rudiments : — the oesophagus, 
from the right epicardiac tube of the thoracic bud ; the intestinal loop, 
as a diverticulum from the oesophagus of the parent ; the rectum, from 
the rectum of the parent. The double origin is compared with what 
Salensky has observed as to the origin of two individuals from one 
ovum in Diplosomidae. 
Synascidiae of Spitzbergen Expedition.^ — Herr B. Gottschaldt 
gives an account of the Synascidians collected during the late Dr. A. 
Walter’s expedition from Bremen. There were found Botrylloides rugosum , 
Colella KueJcentJiali, Leptoclinum structum , Goodsiria borealis spp. nn., 
Synoecum turgens Phipps., and Polyclinopsis Haeckeli g. et sp. n. This. 
* Journ. Coll. Sci. Imp. Univ. Japan, vi. (1894) pp. 279-85 (1 pi.), 
t Comptes Rendus, cxix. (1894) pp. 437-9. 
j Jenaische Zeitschr., xxviii. (1894) pp. 343-69 (2 pis.). 
