SOME A8C1DIANS FROM THE ISLE OF WIGHT. 131 



spring-tides having then almost reached their height. The follow- 

 ing descriptions refer to two individuals which I brought away 

 with me for more detailed examination ; they are given separately 

 in order to indicate the degree of variation the more naturally. 



A. Body oblong, elongated, attached by almost the whole of the 

 left side. Dimensions — Length, 3 inches ; breadth, 1^ inches ; 

 thickness, -f4 inch. An idea of its external appearance may be gained 

 from the figure which Heller gives (1. c. pi. v, fig. 5) to represent 

 a supposed specimen of Alder's Ascidia rudis, but the position of 

 the cloacal aperture is different. 



Test thin, hard, cartilaginous, greatly wrinkled in a longitudinal 

 direction on the right side, almost entirely overgrown by small 

 alg£e, and extensive colonies of the Foljzoon Alcyonidium mytili and 

 some Didemnids, Here and there on the right surface a few 

 minute tubercles may be detected. Oral aperture on the right side, 

 sub-terminal, not prominent, bounded by nine lips ; cloacal ai-terture 

 on the right side near the dorsal edge, very slightly nearer the 

 anterior than the posterior end of the body, bounded by six lips. 



Upon removal of the test the rest of the body is seen to be of a 

 yellowish colour, the musculature being of a rather deeper amber- 

 colour. The oral and cloacal siphons are tubular but short. The 

 oral siphon terminates in nine sub-triangular lips, which are rather 

 prominent, with rounded apices and with a spoon-shaped concavity 

 on their external surfaces. The edge of the siphon is bounded by a 

 thin red line which is discontinuous towards the tips of most of the 

 lips. A small red ocellus is found behind the red line between each 

 pair of lobes, and the surface of the siphon is slightly sprinkled 

 with red dots. The cloacal siphon terminates in six lobes, bounded 

 similarly by a thin red line, but without ocelli. It is directed 

 straight towards its external orifice. 



Musculature coarse and strong, the fibres amber-coloured. 



Viscera disposed as usual in the species, the posterior border of 

 the stomach being nearly ^ inch from the posterior end of the 

 body ; the anterior wall of the intestine at its first bend is on a 

 level with the ganglion ; the posterior wall at its second bend is on 

 a level with the opening of the oesophagus into the pharynx. 



Renal vesicles large, forming a soft yellowish coating over the 

 stomach and intestine ; concretions showing as a small brown spot 

 in each vesicle, when looked at with a lens, but resolving themselves 

 in each case into a compact mass of several concretions, of different 

 sizes and of a yellowish-brown colour, when examined under a low 

 power of the microscope (cf. Roulc). 



Tentacles about thirty in number, short, of unequal sizes, irregu- 

 larly arranged. 



