508 G. HERBERT FOWLER. 
and careful search during April, May, and half of June in this 
year (1889), neither hydroid nor medusoid could be found, I 
publish this incomplete account in the hope that the re- 
mainder of the life-history may be worked out in some future 
year, should this interesting form reappear.! 
The hydroid was originally observed by Mr. F. A. Parsons 
(‘ Proc. Quekett Microsc. Club’ (2), ii, p. 125), but was first 
described in a short note by Professor A. G. Bourne (‘ Proc. 
Roy. Soc.,’ 1884, p. 9), who had discovered it independently, 
and regarded it as a probable stage in the ontogeny of Lim- 
nocodium. This remarkable polyp was in 1888 distributed 
over the whole of the tank, attached to stems and leaves, bits 
of dead wood, and alge, generally in little permanent colonies 
of two or three individuals branching from a common base. 
It is a simple cylindrical tube, about 6 m.m. long, with a 
minute mouth, and is always devoid of tentacles; but, in spite 
of their absence, catches and swallows small Crustacea and free 
Nematoda. No perisarc is secreted, but it forms a loose case 
of vegetable detritus, beyond which the oral end always pro- 
jects. The ectoderm is but little differentiated ; a cap of cubic 
cells at the oral end passes into more flattened cells over the 
general surface, and at the base of attachment are longer 
columnar cells. The nematocysts, as in Hydra, are of two 
kinds, the one oval with an unbarbed thread, the other and 
larger flask-shaped, like that of Millepora, and barbed. The 
mesoglcea lamina is so thin as to be practically unrecognis- 
able. The endoderm is divisible into two regions, which pass 
imperceptibly into each other ; the cells of the upper third are 
highly vacuolated and clear, those of the lower two thirds are 
filled with very brilliantly staining spherical bodies of varying 
size. It is from this latter region alone that gemmation of a 
new hydroid takes place, and the endoderm of the bud con- 
sists only of these cells. As the bud when freed does not 
develop a mouth for some little time, and from their refrin- 
gent and deeply-staining appearance, it is possible that these 
granules are a store of reserve nutriment. Besides the cells 
1 The medusa did not reappear at all this year—November, 1889, 
