ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 751 



of the one which is turned towards the tip of the ovary is jiyriform, and its 

 walls consist of a delicate wall with flat epithelium ; the cords either float 

 freely in the fluid or remain attached to the point where they were de- 

 veloped. In addition to these ovarian cords there are in the ovary three 

 kinds of free cells, some of which have a distinct nucleus, while in others 

 the nucleus is not stained by carmine, and yet others are degenerate egg- 

 cells. The first form of cell is developed by the internal cellular layer 

 enlarging into the interior of the ovary, and in these processes one or two 

 nuclei become apparent ; there are a number of intermediate stages between 

 these and the second kind of cell, and it seems certain that the two kinds 

 differ only in size and in the possession of a nucleus. In the degeneration 

 of egg-cells the yolk-mass disappears, the nucleus and nucleolus alone 

 remaining. 



The formation of the germogen is effected in the following manner : the 

 cells of the sub-epithelial layer, after growing into the interior of the ovary, 

 lose their contour, and their nuclei divide. These form the protoplasmic 

 matrix in which the nuclei of the primitive cells are inclosed. During the 

 growth of the germogen the connective-tissue makes its way inwards. In 

 Hirudo, Nephelis, and others the formation of eggs begins when these cells 

 have developed into egg-cells ; at first the egg-cells are all of the same size, 

 but later on some grow faster than others, and the latter diminish in size. 

 In the egg-cells nuclei, with connective-tissue filaments, make their appear- 

 ance, the filaments being developed when the germogen is converted into 

 the cord. 



New Genus of Lumbricidae.* — Mr. F. E. Beddard describes the type of 

 a new genus of Lumbricidae from British Guiana, which he proposes to call 

 Tliamnodrilus gulielmi. It appears to be most closely allied to the South 

 American genus Anteus by the absence of dorsal pores, position of the 

 nephridiopores, and in the presence of a single pair of spermathecse in the 

 seventh segment. In both genera the setas are similarly disposed, and are 

 in the region of the clitellum, where the setae are specially modified, and 

 resemble those of Urochseta in form, differing, however, in the fact that both 

 ventral and dorsal setee are modified. The nephridia are differentiated into 

 three series, the first of which is represented by one pair. Each gland hero 

 consists of a flattened mass of glandular tubules ; in the second set, of four- 

 teen, the glandular part of the nephridium is very slightly developed in 

 comparison with the extremely elongated muscular sac which communicates 

 with the exterior. In the remaining nephridia the muscular sac is provided 

 with a diverticulum, which is nearly as long as itself. The chief points of 

 difference between Anteus and Thamnodrilus appear to be the much greater 

 extent of the clitellum in the former, the thickening of its anterior 

 mesenteries, and the special modification of the nephridia of its genital 

 segments. The representatives of this new genus are about 6 inches long 

 and 3/8 inch broad. 



Ctenodrilus parvulus.j — Dr. E. Scharff describes a new species of 

 Ctenodrilm lately found by Mr. Bolton in his sea-water aquarium. It is of 

 remarkably small size, being only about 4 mm. long, and having from seven 

 to ten segments. It agrees with G. pardalis in having dark green or violet 

 spots in the skin. The number of bristles in each of the two rows of either side 

 is subject to great variation, and they cannot therefore be used for diagnostic 

 purposes. The " segmental organs " are found in the head segment only ; 

 the dorsal blood-vessel is found only in the three anterior segments. 



* Proc. Zool. Soc. Lond., 1887, pp. 154-63. 



t Quart. Journ. Micr. Set., xxvii. (1887) pp. 591-603 (1 pi.). 



3 D 2 



