ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
367 
Previous investigations show that eyes such as those now described 
are widely distributed among the Sabellidre and Serpulidae, but most of 
the observations were too superficial to admit of detailed comparisons as 
to cell-structure. They are all too simple in structure to admit of any 
direct comparison witn the eyes of Arthropods ; with the eyes of certain 
Mollusca, however, they exhibit close agreement. The protuberant 
mantle organs of the Lamcllibranchs Area and Pectunculus have quite 
the same structure as those of these Annelids, save with regard to the 
sense or refractive cell. There does not appear, in Molluscs, to be 
any specialized axial region external to the nucleus, but there is a 
peculiar conical body which occupies the apical part of the cell. 
In both sets of forms the animals respond very quickly to slight 
sudden changes in the intensity of illumination. The occurrence of stiff 
hair-like processes upon these organs raises the suspicion that some 
other sense organ in addition to or in place of an eye may be here con- 
cerned. The great number and position of tho organs suggests doubts 
as to their usefulness as eyes. And, finally, much of our present 
evidence is very dubious ; Hydroides dianlhus, which has no eye-like 
branchial organs, nor, so far as is known, any other special sense- 
organs, responds fully as well to very slight shadows passing over it 
as does Potamilla. 
Siphonostoma diplochaetos.* — Mr. E. J. Bles has some observations 
on the structure of this Polyclue te, in which he has been able to detect 
the nephridial funnels which escaped previous observers. He is inclined 
to believe that this form is really a modified tubicolous worm, which 
has secondarily acquired an errant habit. 
New Branchiate Oligochsete.f — Mr. F. E. Beddard describes a 
new genus of branchiate Oligocliasta, to which he gives the name of 
Branchiura Sowerbyi ; it was found in some mud from the “ Victoria 
regia tank ” in the Botanical Society’s Gardens, London. It is remark- 
able for having at its hinder end a series of delicate dorsal and ventral 
processes. These last, which give a feathery appearance to the hinder 
part of the body, number about fifty pairs, one pair to each segment. 
In Chsetobranchus, a form recently described by Prof. A. G. Bourne, 
the branchiae are anterior in position, and there is a connection between 
the setae and the branchiae which does not exist in Branchiura. In 
the latter the branchial process arises in the middle dorsal and ventral 
lines ; the structure of these processes is very simple ; they are covered 
by a firm cuticle, beneath which lies the epidermis ; no cilia were 
detected on them. The axis of the branchia is occupied by a cavity 
which evidently belongs to the coelom. Immediately beneath the 
epidermis is a layer of muscles which appears to be continuous with 
the circular layer of the body-wall, and beneath this is the peritoneum. 
Immediately beneath the epidermis there is on each side a blood-vessel. 
In addition to this there is an extensive integumental network of capil- 
laries. After describing other anatomical details, the author points out 
that Branchiura is evidently one of the Tubificidae, but it is nearly 
equally remote from all the genera at present comprised in that family. 
* Rep. Brit. Ass.. 1891 (1892) pp. 373-6. 
t Quart. Journ. Micr. Sci., xxxiii. (1892) pp. 325-41 (1 pi.). 
