INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. S87 



The ectoderm of each metamere is composed of a single transverse 

 row of large cells, of which the first and last metamere contain four 

 each, the others, with the exception of the papilliferous zone, in which 

 the number is not readily made out, contain six or eight each. 



The endoderm forms a sac, the external surface of which exhibits 

 the appearance of delicate muscular bauds. These, the author believes, 

 are due not to separate muscular fibres, but to processes of the 

 endoderm cells, of the same nature as the well-known process of the 

 ectoderm cells of Hi/dra, so that inwj^alura may be said to possess a 

 splanclmopleural pseHclo-mesoderm, while Hijclra has a somatojoleural 

 pseudo-mcsoderm. If this discovery is confirmed it will be one of 

 very great importance.* 



2. Intosliia f gigas.—ThiH species is two and a half times as long as 

 Bhopalura, which attains a length of 0- 108 mm. The body is some- 

 what flattened, instead of regularly cylindrical, less produced at the 

 ends than Bhojjalura, with less distinct metameres and no papilliferous 

 zone. Each segment is composed of several rows of cells, these latter 

 being much smaller as well as more numerous than those of BJiojMlura. 

 No trace was discoverable of the muscular bands, although the author 

 is inclined to think that they exist in a reduced condition. 



3. Gemmiparous Bcprodiiction of Orthonectida, — Under certain cir- 

 cumstances the cells of the endodermal sac undergo great modification, 

 and the sac, increasing gi'eatly in size, breaks through the endoderm, 

 and escapes as a sporocyst. In'the interior of this buds are formed, and 

 from these secondary buds arise, sac-like bodies being finally produced, 

 formed of one layer of cells, from which a second layer is afterwards 

 formed by delamination. 



4. Oviparous Beproduction. — A few developmental stages of Bhopa- 

 lura were observed : enough to show that yolk-division is of a well- 

 marked amphiblastic type, and that the gastrula is formed by ej)iboly. 

 Caryolytic figures were observed in the nuclei of the dividing cells. 



In Intosliia development is as markedly archiblastic : the blas- 

 tula is composed of columnar cells radiating from the central cleavage 

 cavity. The central end of each cell subsequently becomes divided 

 off to form an endoderm cell ; the inner layer arises therefore by 

 delamination. 



5. Systematic. — The Orthonectida are defined by the author as 

 follows : — Metazoa, retaining throughout life the planula form ; 

 having a ciliated ectoderm which exhibits a division into metameres, 

 which do not correspond with any internal division; having also a 

 sacciform endoderm, giving rise to a splanchuo pleural pseudo-meso- 

 derm. Eeproduction (a) asexual, by gemmte, and (&) sexual, the 

 sexes being probably lodged in different individuals. 



The group includes a single species of Bhopalura (B. ophiocomoi), 

 and three species of Intosliia (I. gigas, parasitic on Ophiocoma neglecta ; 



* Professor Giard's figures are unfortunately not good enough to enable the 

 reader to judge for himself of the soundness of the author's conclusions. They 

 show nothing more than a striation of the endoderm. 



1 This genua should properly be Mclntoahia, having been named in honour of 

 Dr. Mcintosh. 



