ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 435' 



Incertee Sedis. 



Development of Phoronis.* — M. de Selys Longchamps gives a 

 full account of his investigations on material from Helgoland and from 

 Naples. Total almost equal segmentation results in a blastula, ciliated 

 in the Helgoland form ; the gastrulation is by embole, a typical in- 

 vagination in the Helgoland form, by a modified " incurving process " 

 in the other species ; the circular blastopore, which is very large, closes 

 from behind forwards, leaving an anterior entrance to the arcbenteron. 

 At the posterior end, on the ventral surface, a median ectodermic diver- 

 ticulum insinuates itself into the blastocoel between the ventral surface 

 of the arcbenteron and the ectoderm. The mesoblast arises from endo- 

 derm cells, liberated from the archenteric wall, but most actively from 

 the anterior region surrounding the persisting portion of the blastopore. 



Larval characters begin to appear ; the stomodaBum is formed, the 

 pre-oral lobe is transformed into a cephalic hood with the central 

 ganglion at its summit, the tentacles originate, the anal papilla becomes 

 distinct. Within this great internal changes go on, the posterior part 

 of the archenteron becomes the intestine, an anus is formed without a 

 proctodaeum, the ectodermic diverticulum seems to form the posterior 

 cavity of the body (ccelomic ?), while the anterior cavity is blastocoelic. 

 But the history of this diverticulum aud the excretory structures re- 

 mains very vague. In a second part of his memoir the author describes 

 the actinotrocha, and his results are closely similar to those of Ikeda, 

 which he did not know of until after his work was done. 



Notes on Actinotrocha.f — K. E. Menon describes this larva with 

 particular reference to the epistome (a new structure, an outgrowth of 

 the collar region, and not a remnant of the pre-oral lobe), the body- 

 cavities, the nephridia, the " notochords," the sub-neural gland, the 

 tubular nerve-ganglion, and the sense-organ in front of the ganglion. 



" If Actinotrocha is related to the Chordata at all, as the presence of 

 three divisions of the body with their corresponding cavities, of collar 

 nephridia, of a dorsal diverticulum of the anterior part of the gut, and 

 of a dorsal tubular nerve-ganglion renders probable, the absence of such 

 important structures as the gill-slits, and of the proboscis pores, shows 

 that the relationship is to be traced through a form like Rhabdopleura." 



A. T. Mastermann J reviews Iwaji Ikeda's § observations on the de- 

 velopment, structure, and metamorphoses of Actinotrocha. He notes 

 their confirmatory value in reference to his own work, and points out 

 that the discrepancies are mostly due (a) to differences of interpreta- 

 tion ; (b) to specific variation ; and (c) to unintentional misunderstanding 

 of his (Mastermau's) statements. 



Rotifera. 



New Rotifers. — F. E. Dixon-Nuttall and E. Freeman || describe 

 Diglena rostrata sp. n., which they have found in the large lake of 



* Arch. Biol., xviii. (1901) pp. 495-597 (3 pis.). 



t Quart. Journ. Micr. Sci., xlv. (1902) pp. 473-81 (1 pi.). 



t Tom. cit., pp. 485-92. 



§ Journ. Coll. Sci. Tokyo, xiii. (1901) pt. 4. 



|| Journ. Quek. Micr. Club, viii. (1902) pp. 215-6 (1 pi.). 



