186 I. IJIMA : HEXACriNELLIDA. I. 



situated in the outermost part of the parenchyme under the 

 dermal layer. On a pi'iori grounds, it seems to me nearly certain 

 that that Anlage is, or is derived from, an aggregation or congeries 

 of archœocytes, much the same as tliat which is so commonly 

 found in the deeper parts of probably all Hexactinellida after 

 maturity. The said Anlage is incorporated in the newly formed 

 bud, with perhaps a portion of the maternal dermal layer in 

 addition ; and, from it should originate by differentiation most of 

 the different soft parts, or at any rate the flagellated chambers 

 of the progeny,— a fact, which is readily conceivable on account 

 of the blastomeric character I ascribe to the archœocytes 

 (pp. 165, 172). Be that as it may, there stands nothing in the 

 way, so far as we know, of calling the above mode of reproduc- 

 tion in R. 7îiirabilis asexual budding,"^' in which process the 

 archseocytes seem to play a very important role. 



*From the character of the organization of the Hexaclinellid body, it is not to be 

 wondered at, if a siniihir budding should take place in the interior of the sponge-wall, in- 

 stead of, or in addition to that, on the external surface. As an indication of such an internal 

 budding is perhaps to be regarded a remarkable case of Sliurocalyptus glabcr Ij , in which I 

 found an innumerable number of small whitisli bodies, distributed throughout the entire 

 parenchymal mass. On close examination they proved to consist of small, thick-rayed 

 hexactins fused together into an irregular fiamework, which was traversed by a few parenchymal 

 spicules. The framework, which I call the baskUctyonalia, is undoubtedly the same as that 

 described by vSciiulze ('99, p. 64; PI. XIV, figs. 2-6) from the buds on the prostalia lateralia 

 of B. mirabilin. It may safely be concluded that a brood of the young had fixed themselves 

 on the parenchymal spicules of the aforesaid specimen of S- (jlaher. The young may have 

 been asexual ly produced exactly as those of R. mirabilis, though not necessarily so. In my 

 opinion, the basidictyonalia is a structure which is formeil quite generally in Rossellids and 

 in certain other Lyssacine families evidently under the inlhience of the hard substratum 

 with which tlie sponge comes in contact at its l)asi.'. It has hitherto been generally overlooked, 

 though the particularly small-meshed and most superficial layer of it has long been known 

 through Scnui-ZE. The little mass of basidictyonalia in both B, mlrabilifi and S. ghiber is to 

 be regarded as having arisen in relation to the old spicules on which the young had attached 

 themselves. It may therefore be ecjually developed in all tlie yomig irrespective of these 

 having been produced asexually or iVom fertilized ova. However, under the assumption that 

 tlie brood in the above case of S. (jlabcr oi iginated from eggs, it seems somewhat strange that 

 the ciliated larvfw were prevented from being si-t at large during the free-swimming period.— 

 Of several Tl. (ßtbr examined by me, the above was the only specimen in possession of a 



