230 RITTER 



Taken in considerable abnndance at Popof Island, Shumagin group, 

 July S, 1S99 ; also in small numbers at Yakutat Bay and Glacier Bay ; 

 found on the under side of stones at low tide. Seventy-five or a hun- 

 dred specimens in the collection. Occurring also in Puget Sound. 



MOLGULA GRAPHICA sp. nov. 

 (PI. xxvii, figs. 6-9.) 



General characters. — Regular in outline, nearly spherical, though 

 somewhat higher than wide and considerably compressed laterally. 

 Attached by small area at posterior end. Siphons not prominent, 

 about 15 mm. apart. Surface of test somewhat uneven, though with- 

 out pronounced interruptions of any sort, no foreign bodies adhering. 

 Qiiite transparent, but the numerous, fine, much-branched, almost jet 

 black vessels showing through distinctly in all parts, giving the animal 

 the very characteristic appearance indicated by its specific name (p1. 

 XXVII, fig. 6). 



Measurements of the only specimen secured : length 3S mm., width 

 30 mm., thickness 22 mm. 



Test. — Thick and firmly gelatinous. Thickness in middle region 

 of body 6 mm. ; somewhat more than this at anterior end, and less 

 posteriorly. The black vessels within it confined mostly to the outer- 

 most layers ; the test cleaves away from the mantle very easily ; its 

 inner surface with a thin stratum, distinctly more opaque. Mantle 

 rather thin, of nearly uniform thickness throughout ; musculature of 

 the usual molguloid kind. 



Branchial apparatus. — Siphons (with animal removed from test) : 

 branchial short and broad with six small almost filiform lobes ; atrial 

 two or three times as long, considerably narrower, tapering at the end, 

 with fovn- lobes. Branchial tentacles, about eight, very large, bushy 

 ones, alternating with about as many more of similar size (p1. xx\'ii, 



%• 9)- 



Dorsal tubercle prominent, hypophysis mouth horseshoe-shaped, 

 opening turned to the right, horns rolled in with about two spirals 

 (p1. xxvii, fig. 8). Endostyle not large; dorsal lamina a plain, rather 

 broad membrane, though with suggestions of a few remote processes 

 on the edge. Branchial sac with seven well-developed and nearly 

 equal folds on each side, from twelve to fourteen longitudinal bars on 

 each fold, no bars between the folds. Transverse vessels very irregular ; 

 the largest and most constant of them placed between the deep infun- 

 dibulse of the sac which reach into the folds ; many finer vessels, ir- 



