ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 755 



the characteristic form is evidently Acanthodrilus ; Rhododr'dus and 

 Neodrilus may be peculiar genera, and Deinodrilus has not been met 

 with elsewhere. The i*auna of New Zealand presents a marked agree- 

 ment with that of Kerguelen, Marion Island, Patagonia, the Falkland 

 Islands, and South Georgia ; so that w'ith regard to the terrestrial 

 Oligochaeta it seems permissible to speak of an "antarctic fauna." 



Anatomy and Histology of Phreoryctes.* — An abstract has been 

 published of Mr. F. E. Beddard's nieraoir on this Oligochfete. Among 

 the new points discovered by the author are the absence of genital and 

 penial setfE ; the clitelluni occupies three to four segments, from the 

 tenth to tlie thirteenth ; its epidermis is formed by a single layer of 

 cells, ditfering from those of the epidermis generally by their greater 

 length and glandular character. The nephriclia of the sexually mature 

 worm commence in the sixteenth segment. In both vasa def runtia and 

 oviducts the distal section is lined with a chitinous membrane, which is 

 continuous with that covering the body; they are in otlier respects 

 closely similar, and the position of the external orifice of the second 

 pair of vasa deferentia is intermediate bftweeu that of the first pair of 

 vasa deferentia and of the oviducts. The ova, which arc, whtn fully 

 mature, of large size (one-half the diameter of the body), and loaded 

 with yolk-granules, undergo their development in egg-sacs which are 

 contained in the fourtemth to the sixteenth segments. The ova and 

 egg-s:ics are more like those of the Tub:ficida3 than those of earthworms. 

 The author agrees with Vejdovsky in regarding PJireorycfes as the type 

 ofadist.net family; this must be placed between the earthworm and 

 the lower Oligochaeta. 



Polar Body Formation in Aulastomum.t — Herr G. Platner describes 

 the f.irmatiou of the first polar body in Aulasfomum gnio, with special 

 reference to the so-called achromatin substances. The centrosoma, 

 which he regards as a constant characteristic of the cell, is recognizable 

 as a definite body, but in the ripe ovum it is quite n.iked wd'hout 

 distinct ensheathiug archoplasma. The polar body extrusion is intro- 

 duced by the division of the centrosoma, roixnd the products of which 

 the yolk spherules become radially disposed. Soon, however, two 

 typical archoplasmic spheres are established round the t^vo daughter 

 centrosomata. Contrary to Boveri's opinion that the ripe ovum w.ia 

 without centrosoma, Platner maintains that spermatozoon and ovu'u are, 

 as regards nucleus and division centres, exactly equivalent at the time 

 of formation of the first segmentation spindle. 



3. Nemathelmmthes. 



Ovary and Oogenesis of Gordius.j — M. A. Yillot describes the 

 long ovarian tubes of the female G'-rdius as consisting of a very d( licate 

 outer layer of the nat ire of connective tissue, and a much thicker inner 

 layer formed of epithelial cells. The ova are not developed in the 

 cavity of the ovarian tiib3S, but in lateral diverticula which are an 

 essential part of them, and which are fe)rmed by exogenous budding of 

 their wall. The contained ova are nothing but isolated and modified 

 epithelial cells. The ova do not pass into the cavity of the ovarian 



* Proc. R. Soc. Edinb., xvi (lSSS-9) pp. 1 17-9. 



t Areh. Mikr. Auat, xxxiii. (18S9) pu. •204-l() (1 p] ). 



: Comptes Rpiidns, cix. (1889) pp. 411-2. 



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