386 W. G. VanNatne — J^rmuda Ascidians. 



Polycarpa obtecta Traustedt. 



Polycarjja obtecta Traustedt, Vestindiske Ascidias Simplices, Aftryk af 



Vidensk. Meddel. fra den naturh. Foren. i Kjobenhavn, p. 51, pi. v, figs. 



7-8, plate vi, fig. 15, 1882. 

 Polycarpa obtecta Sluiter, Tuniciers receullis en 1896 par la " Chazalie," 



M^m. Soc. Zool. France, vol. xi, p. 11. 

 Polycarpa multiphiala Verrill, Additions to the Tunicata and Molluscoidea of 



the Bermudas, these Trans., vol. x, part 2, page 591, 1900; vol. xi, pi. ix, 



fig. 7, 1901. 



Plate LVII. Figures 88, 89 and 92 to 94 inclusive. Plate LXIII. Figures 

 140 and 144. Plate LXIV. Figures 151 and 153. 



Though the type of P. multiphiala Verrill differs in some points 

 from Traustedt's description and figures of the West Indian form, 

 other specimens from Bermuda agree with the latter more closely, 

 and I do not think there is sufficient reason for regarding the two 

 species as distinct. 



The body usually measures somewhat more in length (that is 

 antero-posteriorly) than in breadth (dorso-ventrally) and is, when not 

 distended with water, decidedly compressed in a lateral direction. 

 The test is tough, yet soft and flexible, rather thin toward the pos- 

 terior end of the body, but thickened and much toughened near the 

 anterior end, so that the siphons, though in reality fairly well devel- 

 oped (as may be seen when the animal is removed from the test), 

 usually appear very short. The surface is sometimes partly covered 

 with sand and shell fragments, in other cases bare. The inner sur- 

 face is smooth and nacreous. 



The color of the test is a dirty yellowish or brownish gray, often 

 darkening to red, broAvn, or purplish brown about the apertures. 



The animal is usually attached by a very small area near the pos- 

 terior end, which may be thickened or even produced into a very 

 rudimentary peduncle. Sometimes several individuals are attached 

 together in a loosely connected group. 



The largest specimens found do not much exceed 45™™ in greatest 

 length. They are somewhat less in breadth, and not over 12 to 15™" 

 in thickness when not distended with water. 



The mantle is smooth and rather thin, of a uniform dark biown 

 color. The rather narrow muscle-bands run transversely, longitu- 

 dinally and obliquely, forming a rather open and regular network. 

 The apertures are distinctly four-lobed. The branchial siphon is the 

 longest. 



