Royal Microscopical Society. 145 



and it seems to be inserted into the front wall of the intestine ; it 

 is surrounded by the usual layer of striated muscular fibres, which 

 do not quite extend to the proximal end of the central axis. Neither 

 the vascular canal described by Dr. Moss, nor the ganglionic chain 

 first mentioned by Professor Huxley, is visible in this specimen, 

 but the individuals were so few in number, and the duration of their 

 stay was so short, that the whole of my attention was concentrated 

 on the body, so that those structures, had they existed, might have 

 perhaps escaped notice. The quadrangular elevations on the ap- 

 pendage which were mentioned by Gegenbaur * are not present in 

 this specimen. 



The movements of this animal when under examination are so 

 constant and so vehement, that it is impossible to use the camera 

 lucida in drawing the outlines of its body ; the proportions, there- 

 fore, of its different parts and their relative position to each other 

 may not be quite exact ; but I have endeavoured to get as near an 

 approximation to the truth as is possible by the unaided eye. The 

 length of the specimen given in Fig. 1 is about • 56 mm., while 

 the appendage extends to about three times that length. 



A few days after having found the above-described species, I 

 came across a supply of the short-bodied division of the Appen- 

 diculariae at Weymouth. These f presented several points of interest, 

 and differed a good deal in detail from the tyj^ical A. flabellum. 

 They were rather more quiet under the microscope, so that it was 

 possible to get a tolerably good outline with the camera lucida. They 

 present a pitcher- like form, and the outer tunic is composed of an 

 extremely transparent material, but the viscera, with the exception of 

 the posterior end, are enclosed in a covering of a granular nature. 

 At the anterior extremity this granular wall is continuous with a fine 

 double membrane, which turns inwards round the inhalent aperture, 

 and becomes continuous with the walls of the branchial chamber, 

 which is a globular cavity occupying the anterior portion of the 

 body. Anteriorly, this chamber opens externally by a circular 

 aperture, while posteriorly, it tapers ofi' gradually into the oesophagus. 

 At about the centre it is encircled by a band consisting of three 

 rows of what I take to be square openings or stigmata. If this 

 interpretation should turn out to be correct, these stigmata form a 

 remarkable approximation to the ordinary forms of Ascidians. In 

 no accounts of these animals that I have been able to obtain can I 

 find any mention of such structures. 



I could only find one ciliated branchial aperture, and that was 

 on the side of the body opposite to that which was tm-ned towards 

 the eye, that is to say, if the appendage be considered as being 



* Loc. cit. 



t Their length varied fiotn • 33 mm. to • CO mm., that of the tail from 1 • 08 mm. 

 to l"60mm. 



