BIOLOGY. 
>S pong. 19 
E. Reproduction and Development. 
(i) Germ-Cells, Fertilization. 
Ova? of Euplectella marshalli ; I.tima (29) pp. 181-185. 
(ii) Embi'yology. 
(a) General Accounts. —Shipley & MacBride (53) pp. 73 & 74. 
Reproduction and embryology of bath-sponges; Seurat (52) pp. 267- 
269. 
(b) Early stages, larvae, and metamorphosis. —Larvae of 
Vitrollula fertile and Leucopsacus orthodocus , briefly described. “ The 
Hexactinellidan larva, as regards the arrangement of its cellular elements, 
is essentially similar to that of Monaxonid sponges.” Speculations as to 
the probable course of events in the metamorphosis; pp. 162, 163.— 
Development of the larvae of Leucopsacus orthodocus and Vitrollula fertile , 
pp. 187 & 188; Ijima (29). 
Eggs and larvae in Pachyclictyum glohosum and Spongilla (?) vasta ; 
Weltner (62) pp. 196 & 200. 
(c) Post-Larval Development, Organogeny. —Description of 
a series of young specimens of Regadrella okinoseana , comprising various 
stages “ from one in which the body is smaller than a grain of rice to such 
as have the characteristics of the adult nearly completely developed.” In 
the earliest post-larval stages the body has the wall smooth and imperforate, 
and provided with a single terminal osculum. In specimens 13-15 mm. 
in length the outer surface becomes uneven, and the parietal oscula make 
their appearance. Later (length 20 mm.) the sieve-plate is formed by 
addition of new terminal oscula to the one already present. In the 
youngest stages “ the dermalia are exclusively pentactins, not hexactins as 
in all mature Euplectellids.” Hexactins begin to be formed at about the 
period when the parietal oscula break through; pp. 239-247.—Young speci¬ 
mens of Euplectella marshalli , the smallest 18 mm. in length, and without 
parietal oscula, pp. 103-116.—Young specimens of E. imperialis , pp. 79-83; 
Ijima (29). 
(iii) Asexual Reproduction. 
(a) Fission and Vegetative Budding. —Vacant. 
(b) Germinal budding. —An apparent case of internal budding 
in Staurocalyptus glaber , p. 186 footnote.—Larva of Hexactinellids perhaps 
a “gemmule larva,” formed asexually from an archseocyte-congeries 
(vide ii, b, v, b); Ijima (29) pp. 185-190. 
Development of the buds of Tethya lyncurium. In this sponge-genus 
the asexual method of reproduction by budding seems to have completely 
replaced the sexual method. The entire material of the bud is derived 
from indifferent archseocytes which originate from the deeper parts of the 
sponge-body and travel to the periphery along the spicule-bundles. Each 
bud is at first a collection of numerous archseocytes, similar amongst them¬ 
selves, aggregated in or below the cortex, and is not derived from a single 
cell as formerly stated. The tissues of the bud arise by specialization of 
the indifferent cells, and in no case is differentiated maternal tissue taken 
over into the bud ; but the process of differentiation of the archgeocytes 
“ is not sharply defined as regards time or place,” and may be hastened or 
j retarded in different buds, which therefore differ considerably in early 
