310 University of California Publications in Zoology [Vol. 11 



only a very few had a tendency toward a small apical cone. The 

 bell terminates abruptly with little decrease orally in diameter 

 and i.s partly closed by the thin velum {I'el., pi. 13, figs. 1, 2) 

 which leaves a small opening, about one-third to one-fourth the 

 diameter, in the center. Within the thick jelly-like mas.s (mes.) 

 of the outer bell (o.w.) can be seen the outline of a smaller 

 one similar in shape, formed by the lining {in. w.) of the bell. 

 In the large adult the outer and inner bell attain a height of 

 24 mm. and 18 mm. respectively, and a diameter of 22.5 mm. and 

 17 mm. The smallest specimens observed were 1 by 1 mm. These 

 measurements differ from those of Pewkes, (1889), who gives the 

 dimensions as one and one-half times as high as broad. 



The four-lipped manubrium (man.) extends from the open- 

 ing in the velum to an enlarged sae-like stomach at the apex of 

 the inner bell. From this branch the four radial canals (r. can.) 

 which extend down the sides to the outer edge of the velum where 

 they connect with the circular canal {cir. can.). Throughout 

 most of the length of the radial canals are lateral branches or 

 diverticula (div.). 



Tlie gonads {gon.) are suspended in four groups, one along 

 each of the radial canals where they leave the stomach pouch. 

 They are long, finger-like structures, in advanced .stages reaching 

 nearly to the bottom of the bell. They vary in number from four 

 to eleven in each group, averaging about eight. 



Around the rim of the bell are found in mature forms from 

 forty to one hundred and fifty tentacles (tent.) arranged in from 

 two to four circular groups or rows. Fewkes (1889) gives only 

 three rows. The number varies from as few as eight in the 

 smallest forms (four radial and four inter-radial) to one hundred 

 and sixty in the largest adults. These seem to have been added 

 four at a time or in multiples of four, since those 2 mm. in 

 diameter have twelve to sixteen, those 3 mm. in diameter twenty- 

 four, and so on, only a very few having an odd number. The 

 size also differs, usually the smaller ones being on the inner 

 rows (see pi. 14, fig. 3). In the immature and half -grown speci- 

 mens those tentacles on the four radial canals are larger than 

 the others, bvit this difference becomes negligible in adult forms. 

 These four remain, however, a trifle higher on the bell (pi. 14, 



