vol. 2. pt. 2.] A TAXONOMIC STUDY OF THE SALPIDAE— METCALF. 155 



be one. In that case Quoy and Gaimard's name multitentaculata 

 will be retained for this species. But, as the published descriptions 

 now stand, we must recognize two subspecies. It seems hardly 

 possible that such restudy will show the form I have named radiata 

 to be the same as multitentaculata, as Apstein thought, for both 

 Apstein's and Dober's figures show a character quite divergent from 

 the latter species. 



The arrangement of its muscles, and especially the character of 

 its eyes, show that Traustedtia is more nearly related to Pegea than 

 to any other subgenus. 



The feature of the Traustedtias, which at first glance is most 

 noticeable, is the presence of numerous tentacle-like processes in the 

 solitary individuals. These all correspond in structure to the hollow 

 protuberances found in its aggregated zooids and in other species at 

 the postero-lateral angles of the body. The Thalias show similar 

 but less developed tubes at other points on the body. Some aggre- 

 gated zooids of Thalia, democratica, especially those collected by the 

 Albatross in Philippine waters, have numerous well developed ten- 

 tacle-like processes, which very closely resemble those of Traustedtia 

 (fig. 107, C, p. 114). In this connection we may remember that 

 among the Ascidians — as among the Botryllidae— there are num- 

 erous tubular protuberances of the mantle into the test. The 

 structures in the Salpidae seem essentially of the same character, 

 though far more definite. The postero-lateral protuberances are 

 symmetrically developed in the solitary forms of those species which 

 bear them. In the aggregated zooids, on the other hand, they are 

 unequally devloped on the two sides of the body, as in Pegea confed- 

 crata bicaudata and Traustedtia multilentaculata . It is quite possible 

 that the single postero-lateral protuberance seen in the aggregated 

 zooids of the several species of the subgenus Salpa may be homo- 

 logous with one of the pair present in Pegea or Traustedtia. It is 

 doubtful how far this comparison may be carried, whether it may 

 include the divisions of the postabdomen in the Cyclosalpae and the 

 asymmetrical posterior processes in the other subgenera. The strict 

 homology of these structures throughout the aggregated Salpidae 

 is doubtful, but they are all in the same region of the body, are all 

 protrusions of the test, which, so far as described, contain an inner 

 tube of mantle tissue, the lumen of the tube being continuous with 

 the spaces of the mantle. 



THE SALPIDAE IN GENERAL. 



STRUCTURE AND RELATIONSHIPS WITHIN THE FAMILY. 



Such a review of the species of Salpidae, as we have made, brings 

 out the falseness of the distinction usually used in taxonomic keys 

 to separate the Salpidae from the Doliolidae. The muscle bands in 



