4 rnii'crsity of California Publications in Zoology. [VOL. 4 



of attachment, wholly free from foreign substances. Siphons pro- 

 jecting scarcely at all above the general surface. Attached 

 usually by posterior end, the area of attachment being usually 

 broad and often extended by a flange, more or less regular, of 

 test. Color light grey ; in some regions, especially about the an- 

 terior end, approaching white. Size, longest diameter of largest 

 specimens, 4 cm. ; short diameter of same specimen, 3.5 cm. ; more 

 usual size, longer diameter about 2 cm., shorter about 1.5 cm. 

 Test thin and papery, entire surface beset with minute stellate 

 tubercles, each of which contains several short, rod-like cal- 

 careous spicnles (pi. 1, figs. 1, 2 and 3). Except for presence of 

 the opaque white tubercles just mentioned, test quite transparent. 

 Mantle. Delicate, easily separating from the test, its muscle 

 bands delicate though numerous, especially in the anterior half 

 of the animal, where they are disposed both meridianally and cir- 

 cularly, with also some fibres running obliquely. 



Branchial Apparatus. Siphons very short or wholly absent. 

 Branchial orifice appearing on the surface usually as a longi- 

 tudinal slit. Branchial orifice probably with six lobes. Branchial 

 tentacles from twelve to fourteen, compound, rather large, with 

 several intervening ones much smaller (pi. 1, fig. 4). Hypo- 

 physis mouth simple, elliptical, situated slightly to the right side 

 and far removed from the tentacular circlet. Peripharyngeal 

 groove distant from the tentacular circlet and pursuing a mean- 

 dering course by bending in between the anterior ends of the 

 branchial folds, fig. 5. 



Ganglion Extremely long and narrow, extending from in 

 front of the hypophysis backward behind it to a distance three or 

 four times the length of the latter. Dorsal lamina a broad, 

 heavy, crenulated membrane beset with numerous conical pro- 

 cesses. Branchial sac, with nine folds on each side, eight of which 

 are large, the one on each side of the endostyle being small. In- 

 ternal longitudinal vessels on each side of each fold varying from 

 six on the smaller folds to nine or ten on the larger. Infundibula 

 large, quadrilateral, frequently notched at their inner borders, 

 i.e., the borders toward the inner margins of the folds. Stigmata 

 small and irregularly distributed, usually short elliptical, but in 

 some regions somewhat curved. Those of the infundibula gener- 



