60 bulletin: museum of comparative zoology. 



For the name of the species I am also indebted to Dr. Ritter, who 

 has kindly allowed me to quote his manuscript name, DistapUa occi- 

 dentalis. With the material at my disposal, which, for the most part? 

 consists of only pieces of colonies, and these from but one of the many 

 localities where the species has been encountered, it would be unwise to 

 attempt a complete diagnosis. I will, therefore, endeavor to give only 

 a few of what seem to be the distinctive features. 



The colonies vary in shape, being both incrusting and pedunculate ; 

 in the latter case they are often mushroom-shaped. The color also 

 varies j in preserved specimens it may be whitish, salmon-yellow, brown- 

 ish, or purple. The zooids are small, adult ones exceeding 3 mm. by a 

 few micra only, and they are always hermaphrodite, ovary and testis 

 being well developed at the same time. The ramifications of the pyloric 

 gland do not end in swollen ampullae. The stomach, though nearly 

 smooth on the outside, is thrown into irregular folds within, so that in 

 whole preparations it has a reticulated appearance. The test is com- 

 posed of the thin walls of numerous lacunae. It contains many ectoder- 

 mic vessels, and these do not anastomose. These characters easily 

 separate D. occidentalis from D. magnilarva (Delle Valle, '82, p. 200 ; 

 Lahille, '90, p. 157), D. luhrica (Drasche, '83, pp. 22-23), D. vallii^ 

 (Herdman, '86, pp. 128-132), and I), livida (Sars, '50, p. 154; Huit- 

 feld-Kaas, '96, p. 1 1). It appears to be distinguished from D. clavata 

 (Sars, '50, p. 154; Huitfeld-Kaas, '96, p. 11) by the great length, 

 6 cm. of the narrowly clavate colony. This leaves D. rosea (Delle 

 Yalle, '82, p. 202; Lahille, '90, pp. 174-175; Caullery, '95, p. 8) and 

 D. intermedia (Heiden, '93, pp. 348-349), with which our species 

 seems to be closely related. If D. intermedia is found to have unisexual 

 zooids, then this character will separate it from D. occidentalis. If, on 

 the other hand, the colonies examined by Heiden were not fully mature, 

 and the zooids become hermaphroditic later, then his species and D. rosea 

 must be united. Thus wo get D. rosea as the closest, and a very close, 

 relative of D. occidentalis. In fact, the only differences seem to refer 

 to characters of minor importance, such as the range in shape and color 

 of the colonies, and the inequalities on the inner surface of the stomach. 



1 If, as Herdman says (pp. 128, 130), D. valUt contains no bladder cells in the 

 test which "consists of a homogeneous matrix in which are scattered numerous 

 small test cells and larger pigment cells (Plate XVIII. Fig. 4)," tlien this species 

 must be considered rather distantly related to the other members of the genus, for 

 in all of these in which the structure of the test has been examined, it has been 

 found to be lacunar. 



