36 University of California Publications in Zoology. [Vol. 4 



greatly so. Semi-transparent, the strong muscle bands of the 

 mantle, and the digestive tract distinctly visible through the test. 

 Siphons distinct though not long. Some of the specimens clinging 

 to fragments of hexactinelid sponge by the posterior end and left 

 side ; others adhering to a compound ascidian, and still others to 

 an anemone. Largest specimens about 2.5 to 3 cm. in length. 

 Test, soft, transparent, rather thin, containing great numbers of 

 cells, many of which are of peculiar granular character. Mantle 

 muscle bands strong, usually six on each side, scarcely stronger 

 on one side than the other, those running lengthwise of the body 

 converging to a point at the posterior end of the animal (pi. 3, 

 fig. 35) ; circular fibers in the siphons only. 



Branchial Apparatus. — Siphons both at anterior end and not 

 far apart, rather prominent, the atrial a little longer. Branchial 

 with eight lobes (normally) and the atrial with six (normally). 

 Branchial tentacles numerous, more than 200, filiform, of 

 several lengths, the longer and shorter not regularly alternating 

 (fig. 36). Hypophyseal mouth simple, narrow-elliptical, the 

 long axis extending radially with reference to the tentacular 

 circle; gland on ventral side of ganglion, smaller than the 

 ganglion. Dorsal languets finger-like with broad transversely 

 expanded bases, rather close together. Branchial sac Avith both 

 longitudinal and transverse internal vessels ; also with stout 

 papillae. Transverse vessels of two sizes, the larger crossing the 

 stigmata at their middle, the smaller in pairs one each side of 

 each larger vessel, both crossing the stigmata. Longitudinal 

 vessels slightly larger than the smaller transverse ones. Bran- 

 chial membrane proper, without folds, stigmata straight, long 

 and narrow, in regular series, the vessels separating the series 

 of two sizes, the larger and smaller alternating regularly. From 

 four to six stigmata between each two internal longitudinal 

 vessels (pi. 3, fig. 38). 



Digestive Apparatus. — Situated on left side far toward the 

 dorsum, general form that of an elongated open S. Esopliagus 

 short, stomacJi regular, elliptical in longitudinal section, the long 

 axis usually about twice the length that of the transverse; wall 

 regularly and closely plicated, the plicae about twenty in num- 

 ber; situated at the extreme posterior end of the body, the long 



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