390 W. G. Van Name — Bermuda Ascidians. 



riorly. The test is tough and coriaceous, of a dirty yellowish color, 

 becoming a purplish brown or red toward the anterior end of the 

 body. It is not very thick at any point. On the outer surface it is 

 finely wrinkled ; within it is smooth and glistening. 



The largest of these specimens does not exceed 30 mm in length, 

 and most of the individuals are considerably smaller. 



When removed from the test the body is ovate, with both the 

 siphons near one end. The mantle is of a yellowish color, and rather 

 thick and opaque, with numerous longitudinal muscle-bands, but few 

 conspicuous bands running in other directions. The internal organs 

 cannot be seen very readily through the mantle. 



The tentacles vary in number in different specimens. As a rule 

 the larger the specimen the more tentacles. The individual shown 

 in figure 78 had hardly over 30, those shown in figures 76 and 77 

 had from 40 to 50. The tentacles are of several sizes. Sometimes 

 they are arranged with some regularity ; one tentacle of a given 

 size being placed midway between two of the next larger size and so 

 on ; but this arrangement is not very strictly adhered to. Often 

 those of the smallest size will be wanting in many of the places 

 where, according to the above scheme, they should occur, or they 

 may be represented by a mere tubercle, so that it is hard to say 

 whether it should be counted as a tentacle or not. No doubt as the 

 individual increases in size these grow out into tentacles. 



The dorsal tubercle is variable in size and form, and its orifice 

 had a different shape in each specimen examined, though always 

 some modification of the U-form. The ends were not spirally coiled 

 in any case. Evidently the form of the dorsal tubercle will not do 

 as a specific character in this genus, if indeed it is of much value in 

 any other genus of this family, which I am inclined to doubt. 



The branchial sac has four distinct folds. These vary in size rela- 

 tively to the interspaces in different individuals. Figure 09 shows a 

 section extending clear across one side of the sac near the middle of 

 the body. (Toward the ends of the body, the sac is more contracted 

 and the number of stigmata between the bars becomes smaller.) It 

 is taken from the individual shown in fig. 77, a fully adult and fairly 

 large specimen. In this it will be seen that there are about 10 

 stigmata in the largest meshes in the interspaces between the folds 

 (14 each side of the endostyle and 8 each side of the dorsal lamina). 

 In the dorsal part of the sac, the bars are more crowded, and the 

 maximum number of stigmata in a mesh is about eight. The first 

 fold begins at the third bar from the endostyle and there are four 



