REPORT ON THE CALCAREA. 33 



Hetcrcpegma nodus gordii, Leucilla liter, Leuconia typica. In all these cases the larvae 

 belonged to the type known under the name of Amphiblastula. 



As far as the spermospores are concerned, I can only corroborate my former state- 

 ments ! as to their existence in the Calcarea, as well as in reference to the mode of their 

 development. I have observed them in Leucosolenia poterium (?), in most of the 

 Syconidse, in Leucilla uter, Leuconia multiformis, Leuconia typica, Leucetta hceckeliana, 

 Eilhardia schulzei, in Sycon arcticum and Leucilla uter together with Amphiblastulse. 

 In one specimen of Leucosolenia poterium (?) the spermospores were pretty numerous ; 

 but in almost all cases I found them outside the walls of the sponge, close to the 

 flagellated cells. I was not able to account for this strange phenomenon, till 

 Dr. Vosmaer kindly showed me this spring in Naples some sections with spermospores 

 made from an Asconid exceedingly well preserved. As the observation belongs to 

 Dr. Vosmaer and not to me I cannot here enter into particulars ; I can only say that 

 what I have seen in his preparations gives a very simple explanation of how Prof. 

 Hfeckel arrived at his statements 2 as to the endodermic origin of the spermospores. Be 

 that as it may, their mesodermic origin is beyond all doubt, and, apart from the 

 Syconidas and Lenconidse, I found in one case in the same Leucosolenia poterium (?) one 

 spermospore lying quite obviously in the mesoderm. No mistake was possible, for it 

 was found in a spot forming a common meeting-point of several branches of the 

 colony, so that the mesoderm appeared in the section, not as usually happens in the 

 Asconidse as a, so to speak, mathematical line, but as a plane of comparatively broad 

 surface. In this (PI. III. fig. 1), as well as in other instances, a thin membrane around 

 the spermospore was to be discerned very easily. In two cases this membrane had a 

 slight thickening upon it as represented in the figure just alluded to, which I am inclined 

 to regard as corresponding to the place of the nucleus of the covering cell. This 

 supposition will appear to the reader very natural if he compare the picture just mentioned 

 with the fig. If, PI. VI. representing two spermospores of Leucilla uter. The few 

 spermospores I was able to discover in Leucetta hceckeliana were found lying, not in the 

 parenchyma, but in the cortex, not very far, however, from the zone of the flagellated 

 chambers (PI. VIII. fig. 2). 



It is a very interesting fact that the mode of development of the spermospores, as I 

 have described it in Sycandra raphanus, by no means seems to be confined to the Class 

 Calcarea. I have also found the same in a horny sponge (an Aplysinid), and I shall 

 return to the matter in my Report on the Challenger Keratose Sponges ; and as in the 

 form just mentioned the spermospores are also very small, there can — in view of 

 F. E. Schulze's statements as to the spermatogenesis in Aplysilla, 3 Spongelia* and 



1 Sitzungsb. d. math.-naturw. CI. d. k. Akad. d. Wiss. Wien, Bd. lxxxvi. p. 277, 1882. 



1 Kalkschwamme, Bd. i. p. 150. 



3 Zeitschr.f. wis*. ZooL, vol. xxx. p. 412, 1878. * Ibid., vol. xxxii. p. 145, 1879. 



(ZOOL. CHALL. EXP. — PART XXIV. — 1883.) Aa 5 



