NO. 1989. A8GIDIANS FROM NORTHEASTERN PACIFIC— RITTER. 485 



more roughened, almost warty. Test thin and tough, of quite 

 uniform thickness throughout. All individuals firmly attached, some 

 to the peduncles of Boltenia and some to others of their own kind; the 

 area of attachment not large. Largest individuals about 1 cm. in 

 diameter; mostly smaller. 



Resjpiratory system. — Orifices indistinctly four-lobed. Branchial 

 tentacles about 55, simple, all in one circle, long, and of approximately 

 uniform length. Atrial tentacles present, slender, about 20 in num- 

 ber. Hypophysis mouth an almost but not quite closed circle, the 

 opening turned toward the left. Branchial sac with four folds on 

 each side ; formula of internal longitudinal vessels in two specimens 

 as follows : 



• No. 1. EndostyleJQ_^^_Q_^_^_^^_Q_^_Q ^ 



AT o -IT 1 . 1 [0-5-0-4-1-5-1-^-0 L. 

 No. 2. EndostyleJQ_^^_Q_^_j_^_^_^_Q ^ 



Stigmata straight, about 8 to 20 in a mesh. Dorsal lamina a plain 

 broad membrane. 



Alimentary system. — On left side of body; esophagus rather long, 

 slender and curved; stomach well-defined, regular, spindle-shaped, 

 waU closely and regularly longitudinally folded, the folds 25-27 in 

 number; from the stomach the intestine forms an almost circular 

 bend, coming back to form a contact with the esophageal end of the 

 stomach, at which point it makes an abrupt turn forward and down- 

 ward to terminate in a narrow hook; anus with a smooth lip. 



Rein-oductive system. — On right side, a trident-shaped body, the 

 three prongs springing from a common basal piece in general running 

 clearly parallel with one another. Endocar'ps present and well 

 developed. 



Hartmeyer expresses the view that B. adolphi may not bo a good 

 species; that it may have to be united with D. aggregata. 



The examination of these specimens puts beyond question the 

 validity of the species. From aggregata it is distinguished by the 

 greater number of tentacles and fewer number of gonadeal prongs. In 

 four specimens the tentacle numbers were 51, 54, 55, and 58. This 

 is more than double the number ascribed to aggregata, a difference too 

 great to be due to fluctuating variation. 



The three-parted state of the gonads appears constant, though in 

 one of the individuals examined one of the prongs was connected with 

 the others by a small isthmus only, suggesting that in other cases it 

 might be wholly separated, and so leave the gonad in the two-branched 

 state which Hartmeyer (1899) has found to prevail in some specimens 

 of D. IcuJcenthali. As a matter of fact, the last-mentioned species 

 would seem to be very close to D. adolphi, though Jcilkenthali has a 

 larger number, 64, of tentacles. 



