ritter: octacnemus. 235 



otherwise. One of these is the presence of a decided ventral, or anterior, 

 lip to the branchial orifice. This is shown in Plate 1, Figure 1. This 

 considerably resembles the lip in the corresponding position in various 

 species oi Salpa, though as we shall see later this resemblance can have 

 no taxomomic significance. In the normal specimen in preservation it 

 gives the orifice a more semilunar shape, Figure 1, than Herdman's 

 Figure 6 indicates. 



As already stated, the posterior enlargement, on whose dorsal and 

 posterior surface the atrial orifice is situated, is more like tliat in 

 Herdman's than in Moseley's specimen. As a matter of fact, in all the 

 "Albatross " individuals it is even larger than in Herdman's figure. This 

 is, I consider, really to be accounted as part of the body of the animal 

 instead of a prominence on the body, as Herdman has expressed it. 



But the most important extension of our information about the 

 superficial characters of tlie species I am able to make is in connection 

 with the adhesive disc. Tiie interest attaching to this comes from the 

 question of whether or not the animal really lives fixed to the bottom 

 or is a swimmer, at least for a portion of its life. Moseley states that the 

 " process," as he calls the part of the animal of which we are now speak- 

 ing, is "terminated outwardly in a tangled mass of rootlets, massed 

 amongst which was found much sand and shell-particles from the 

 bottom." " The ascidian," he says, " was evidently attached by this 

 process or pedicle." The minute structure of the rootlets Moseley 

 appears not to have attended to particularly. With reference to the 

 South American specimen Herdman says : " The dorsal projection 

 which contains the viscera is roughened on its lower surface, and if 

 the body were attached to S(jme foreign object it must have been by 

 this part." Herdman has always, as I judge from mention of Octacnemus 

 in various of his publications, regarded it as only probable that the ani- 

 mal is attached. Metcalf, 1893, 1900, observed the hair-like processes 

 on 0. patagoniensis, recognized their similarity with those on various 

 simple ascidians, and consequently did not hesitate to conclude that 

 this is an attached species. 



It is thus seen that all who have studied Octacnemus have regarded 

 it as a bottom dweller. ]\Iy observations certainly confirm this view ; 

 but at the same- time the strength of" the circular muscle bands of the 

 oral disc suggests that at some period in its life the animal may possibly 

 be a swimmer.^ It is possible, however, that the co-ordinated action of 



1 Since writing the above Mr. Agassiz has called my attention to the fact that 

 he has recorded (Mem. Mus. Comp. Zool., Vol. 26, p. 91) the taking of Octacnemut 



