292 MR. H. N. MOSELEY ON TWO NEW 



Between the mouth and rectum, in the middle line, lies the heart-shaped nerve- 

 ganglion, immediately heneath which is a spherical body, which had the appearance of a 

 thin-walled sack full of a milky fluid. The wall of this sac is composed of a layer of 

 cells of rectangular outline, from the inner surface of which fine hair-like processes 

 depend (fig. 13). The hairs are not straight, hut wavy, and appeared stiffer than 

 ordinary cilia. This sense-organ was not in sufficiently good preservation to allow of 

 more accurate histological investigation. A large nerve from the ganglion passed directly 

 over it in the middle line. 



A pair of strong muscular masses is developed at the posterior part of the nucleus, 

 one mass lying on either side. These muscles appear to take origin from the under- 

 side of the thickened horizontal membrane above, and to terminate on the sides of the 

 posterior part of the nucleus. The terminations of the muscular slips composing the 

 muscles are bifurcate (fig. 10, mn). Other narrow transverse muscular bands are present 

 between the mouth and rectum, embracing the fore part of the nucleus (fig. 10, mb). 

 The use or homologies of these muscles are not apparent. 



The endostyle lies in the middle line, at the back of the nucleus, between the pair 

 of posterior muscles of the nucleus (fig. 10, n). It is very short. It showed the cha- 

 racteristic structure of the Asciclian endostyle — long, fine, granulated, spindle cells, packed 

 close side by side, with their long axes at right angles to the length of the organ. 



The relation of the endostyle to the horizontal membrane was not observed, since the 

 organ was only discovered after the nucleus had become detached from the membrane. 

 The endostyle was then found tucked in between the paired posterior muscles of the 

 nucleus. It is placed in the position given to it in the figures, because this seems to be 

 the necessarily correct one. The organ, at all events, is on the ventral side of the 

 animal, or on the side of the mouth opposite to that on which the nerve-ganglion lies, 

 which is its normal seat. 



The length of the base of the Ascidian was 5'5 centims., breadth 4'7o centims. ; extreme 

 length between tips of the protuberances 7"5 centims. 



On the whole this very perplexing animal appears to be an Ascidian in which the 

 respiratory sac is flattened out so as to become nearly horizontal, and in which no gill- 

 network is present. In Cystmgia (Bronn, Kl. und Ord. ii. p. 131) a gill-network cannot 

 be distinguished. 



The radial muscles belong to the longitudinal set of other Ascidians and are internal ; 

 the circular are external in relative position. I can find no homologues of the muscles 

 of the nucleus. In having the viscera contracted into so small a nucleus, the animal 

 resembles Salpa. The nerve- ganglion is abnormal in position, in being situate on the 

 nucleus. It, nevertheless, is normal, in lying between mouth and anus, whilst the endo- 

 style is on the opposite side of the mouth as in other Ascidians. 



The name Octacnemus bytliius is proposed for this curious eight-rayed deep-sea form. 



The above account is the result of an examination of the animal in the fresh condition. 

 A further investigation of the specimen as preserved in spirit is much to be desired. 



