396 W. G. Yan Name — Bermuda Ascidians. 



Microcosmus Heller, 1877. 



Distinguished from Halocynthia by the plain, nntoothed dorsal 

 lamina, and by the narrow intestinal loop. 



Microcosmus miniatus Veirill. 



Mierocosinus miniatus VeiTill, Additions to the Tunieata and Molluscoidea of 

 the Bermudas, Trans. Conn. Acad. Sci., vol. x, p. 590, 1900. 



Plate LVI. Figure 79. Plate LVII. Figures 91 and 95. Plate LXII. 

 Figures 129 and 130. Plate LXIV. Figure 148. 



Test more or less comj^letely red or dull orange-red externally, 

 rather thick and tough, somewhat cartilaginous. In adult specimens 

 it is much wrinkled and raised (especially on the dorsal surface and 

 about the apertures) into prominent ridges with sharp rough edges. 

 Young specimens are much smoother. 



The shape is ovate, more or less elongated; the apertures are widely 

 separated. The attachment is by an area of considerable extent on 

 the ventral side, generally near the posterior end. In external 

 appearance this species closely resembles Halocynthia rubrilabia, 

 described above, but is usually colored more intensely and extensively 

 red than that species, and the body is often somewhat more elon- 

 gated. Internally the test is smooth and peai'ly and less deeply 

 coloi'ed than on the outside. 



Size of the largest specimen, 50 by 35 by SS"^"". 



Removed from the test, the animal is ovate wnth very widely sep- 

 arated and divergent siphons of very vai'iable size and length in 

 different specimens, both four-lobed. The mantle, especially near the 

 apertures, is more or less tinged with red. Its muscles, stronger on 

 the dorsal part of the body, are gathered into very distinct and mod- 

 erately thick bands, which for the most part cross each other nearly 

 at right angles and form a rather open network, so that the internal 

 organs are more or less distinctly visible through the mantle. 



The tentacles are bipinnately branched. There are about 8 or 10 

 larger ones alternating with others of smaller size and between them 

 are a variable number of still smaller ones. Even the smallest ai"e 

 somewhat branched. The aperture of the dorsal tubercle had 

 spirally incurved horns in the specimens examined. 



The number and arrangement of the folds of the branchial sac 

 proved to be quite constant in a number of individuals of various sizes 

 from about 15™™ in length up to individuals of full size. There are 

 nine folds on each side of the sac, but the last one (that nearest the 



