Alcyonella. Z. ASCIDIOIDA. 313 



and is crowned with a " beautiful expansion of tentacula, about fifty 

 in number, arranged in an unbroken circle, which is, however, de- 

 pressed into a deep concavity on one of its sides, so as to produce the 

 appearance of a double row of tentacula in a horso-shoe form. About 

 one thousand six hundred polypes are situated on a square inch of sur- 

 face of the mass, consequently the number of polypes" in one speci- 

 men which weighed 17 ounces, and measured 14^ inches in circum- 

 ference, " may be computed at one hundred and six thousand, and the 

 tentacula at five millions three hundred and twenty thousand I" The 

 mouth is, as usual, in the centre of the crater formed by the tenta- 

 cula, and is the entrance to an alimentary canal that, descending in 

 the body, swells out into a stomach, and then bends to gain an up- 

 ward course, having its termination exterior to and underneath the 

 indenture in the tentacular circle. " The lower portion of the stomach 

 is of a bright brown colour, longitudinally striated. The colour ap- 

 pears to depend upon the alimentary materials which it contains, and 

 the vertical striae are probably produced by folds in the organ. On 

 lacerating the stomach, the brown matter escapes in the form of in- 

 numerable minute grannies. A sort of vermicular motion is some- 

 times observed in the stomach." 



The ova ai'e generated in that portion of the polype-tubes which 

 is prolonged from the stomach through the common mass, (fig. 2,) 

 not germinating in any certain point, but from all the gelatinous sides. 

 ♦' Those which are perfectly matured are of a dark reddish-brown 

 colour. Others of the same size have their external envelope opaque 

 and white ; others are somewhat smaller and translucent, whilst some 

 are very minute and perfectly transparent. The mature and imma- 

 ture ova appear scattered indiscriminately throughout the tube. The 

 ova ai*e stated by Raspail to occur in a double series ; I have, how- 

 ever, almost invariably found them in a single row. M. Raspail also 

 says he has been able to see the small filament which connects the 



ova to their containing membranous tube." There appears to be no 



duct or aperture through which the ova can escape, their liberation 

 being apparently dependent on the decomposition of the body. This 

 is of two kinds : " In the first, the papilla which during life closes 

 the tube, dies and becomes softened, ragged, and flocculent, and in 

 this state no longer forms a barrier to the exit of the ova. In No- 

 vember, many of the specimens were seen in this condition. On ex- 

 amining the surface of the polypiferous masses, they were seen co- 

 vered with ragged shreds of membrane instead of the well-defined 

 conical papillae' or expanded polypes. In the second stage, air is dis- 

 engaged from decomposition of tlie contents of the horny tube or 



