30 SUMMARY OF CURRENT RESEARCHES RELATING TO 



older naturalists, he places under the Ascidice simplices. He discusses 

 their proper systematic position, and, as against those who would look 

 on them as being intermediate between the simple and the compound 

 Ascidians, he points out that the power of reproducing by gemmation 

 has a more apparent than real importance. " The buds on the stolons 

 of the Clavelinidce are developed from the ends of the blood-vessels, 

 and are at first merely slight enlargements similar to and comparable 

 with the knobs on the end-twigs of the vessels in the test of an Ascidia, 

 these last vessels being comparable with those in the stolons of the 

 Clavelina." In fact, the simple Ascidians have been observed to form 

 stolons, though gemmation is not known to occur. In fine, the author 

 forms a family — the Clavelinidge — to contain those simple Ascidians 

 v?hich reproduce by gemmation and form colonies. In addition to 

 Clavelina, Perophora, and, possibly, Wiopalcea, this family contains a 

 new genus, Edeinascidia. Like Ciona and Bhopalcea, it has well- 

 marked internal longitudinal bars, but, unlike them, it has no papillae 

 to its branchial sac. Three species are placed in this genus, all of 

 which are new — E. crassa, E. fusca, and E. turbinata. Clavelina 

 oblonga is a new species, as is also C. enormis. Of the latter the author 

 notes a specimen which is evidently " pathological " — two individuals 

 being in adhesion, and having an irregular stem-like base, which seems 

 to owe its development to the irregular surface to which the colony 

 was attached. 



North Polar Polyzoa.* — The number of species of Polyzoa 

 brought home from the North Polar Expedition is not large, as the 

 present list only consists of fifteen species, of which Mr. G. Busk 

 considers three new ; the remainder are all known, and mostly com- 

 mon in the Northern Seas. 



The new species are named Flustra serrulata, Eschara perpusilla, 

 Farella sp. 



Metamorphosis of the Bryozoa.f — M. J. Barrois gives a detailed 

 account of the different stages of the development of the Escharine 

 group of the Bryozoa, in which he is enabled to connect them better 

 than was done in his own well-known previous memoir and those of 

 other investigators. 



Stage 1. Blastula. — Consists of eight rows of five cells each, 

 running parallel to the long axis of the ovum, to the poles of which 

 the two lateral rows alone extend, and round which they form a 

 ciliated zone. Stage 2. Gastrula. — Formed by the invagination of 

 four large cells on the oral surface. The aboral series of cells become 

 transversely segmented ; those of the ciliated zone longitudinally so ; 

 the median cells of the aboral face elongate, producing a cross. 

 Stage 3. Mounded Embryo. — Has the same general shape, viz. rounded 

 oblong, with the long axis at right-angles to the invagination-orifice, 

 as in the last stage. The four invaginated cells form eight or nine 

 cells by segmentation ; of these, a central raised mass, in which the 

 individual cells are difficult to distinguish, becomes free from the 



* Joura. Linn. Soc. (Zool.), xv. p. 231 (1 pi.)- 



t Ann. Sci. Nat. (Zool.), ix. (1880) Article No. 7, 67 pp. (4 pis.) 



