ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 53 



fertilised externally. Segmentation was not very regular, the blasto- 

 meres frequently not dividing simultaneously, so that odd numbers of 

 cells occurred. The " plasmic corpuscles " described by other authors 

 were found within the advanced blastula, and shown to be distinct from 

 the mesoblast cells. In regard to gastrulation, the author finds that 

 both the anterior diverticula and the ventral groove are simply temporary 

 remnants of the original mesentoblast, and sooner or later split into 

 mesoblastic and entoblastic cells. 



In regard to the Actinotrocha, it is probable that the four forms 

 found near Misaki represent as many species of Phoronis ; the four 

 types are described by the author in detail. The author believes that 

 Masterman's " oral and pharyngeal grooves," compared by the latter to 

 the gill-slits of Chordata, are artifacts. The body-cavities of the larva 

 are not enterocoelic but schizocoelic in origin, and do not genetically 

 correspond to those of the adult. The preoral cavity of the larva largely 

 disappears in the adult, the collar-cavity becomes avascular space in the 

 adult, while the trunk-cavity only of the larva persists as the infraseptal 

 cavity. The author does not find that, as stated by Masterman, the 

 canals of the nephridia open into the collar-cavity in the larva, the 

 nephridia seem to him to end blindly. The paper contains numerous 

 other details in regard to the structure of the Actinotrocha and the 

 process of metamorphosis, but for those the original paper must be 

 consulted. The author does not make any suggestions as to the affinities 

 of Phoronis. 



New Species of Phoronis.* — Harry Beal Torrey has examined five 

 specimens of this genus from Humboldt Bay, California, and three from 

 Puget Sound. This is the first time Phoronis has been recorded from 

 the Pacific, and all the specimens prove to belong to one species, 

 described as Ph. pacifica. The lophophore is spirally coiled with li— 2 

 complete turns, the tentacles number 170-200, the lophophore organ 

 when present is very variable in form, and may be absent, the tube is 

 straight, cylindrical, and encrusted with sand, the sexes are possibly 

 separated. The material was not well preserved, but it was made out 

 that the longitudinal nerve-trunks unite across the median line between 

 mouth and anus. Just beneath the median longitudinal blood-vessel 

 there is a ridge of thickened epithelium in the descending limb of the 

 digestive canal. 



Free Phase in the Life-Cycle of Orthonectids. f — M. Caullery and 

 P. Mesnil think that they have found evidence to prove that there is a 

 free phase in the life-history of Orthonectids, — a phase in which the 

 female is fertilised by the male, and in which the ova develop into free- 

 living embryos. Eventually, the embryos invade new hosts and assume 

 plasmodial form. 



From observations on Bhopalura ophiocomse (from Amphiura squamata) 

 the investigators conclude that there is an alternation of (1) a parasitic, 

 sporocyst, or plasmodial phase producing males and females; and (2) a 

 free-living phase of non-sexual embryos which become plasmodia after 

 invading a new host. 



* Biological Bulletin Boston, ii. (1901) pp. 2S3-8 (5 figs.), 

 t Comptes Kendus, exxxiii. (1901) pp. 502-3. 



