E. MARSHALL!. — EEPKODUCTIVE ELEMENTS. 183 



traceable to a different source, viz., to the archseocyte-congeries 

 ■\vliieh were commonly met witli in both of the specimens I had 

 of the species. I sliall return to this point soon again. 



The second case relates to a rather small specimen (110 mm. 

 long) of E. marshalli, which was killed August 10, 189o, by means 

 of corrosive-sublimate dissolved in sea-water. The specimen had 

 a portion of the wall evidently repaired after an injury by which 

 some of the external ledges had been torn ofi'. Xot only in the 

 parts thus restored but also in the old uninjured parts, there 

 were found a number of peculiar, plump-bodied, variously sized 

 cells (PI. V, fig. 4o, x.), the like of which I had never discovered 

 in any other specimen. The cells occurred in irregular distribution, 

 in pliices abundantly, on both the external and the internal 

 trabecule as well as on the dermal and the gastral membrane, 

 sometimes also on the apparently naked surface of certain spi- 

 cules. Less frequently were they met with on the convex ex- 

 ternal surface of chambers, along with the usual archteocytes. 

 They seemed to be simply adhering to the parts mentioned by 

 a small portion of their surface or by a broad base. 



In shape the cells are generally more or less spherical ; 

 under certain circumstances they are hemispherical, fusiform or 

 rather irregular. The larger ones measure 10-15 y, sometimes 

 23 /j!, in diameter, — a size which is on the whole considerably 

 larger than that of the largest thesocyte. The smallest cells are 

 in no way distinguisliable from, or are but slightly larger than, 

 the archseocytes, with which they are thus connected by an un- 

 interrupted gradational series of intermediate forms. There can 

 be no doubt that the large cells belong to the sponge and that 

 they take origin by growth from certain archfeocytes. I have 



