REPORT ON THE TUNICATA. 47 



The alimentary canal of the specimen collected on May 12, I87G, is shown in 

 PI. III. fig. 7. 



DoUolum affiue, n. sp. (PI. III. fig. 6). 



Body of the usual cask-like form. 



Mantle liavino- the usual eight muscle bands. 



Branchial Sac large. Stigmata commencing dorsally midway between the first and 

 second muscle bands, and extending back to midway between the fifth and sixth ; 

 ventrally they extend forwards nearly to the third muscle band. 

 . Endostyle extending from the second to the fourth muscle Ijand. 



In this new species I place the following specimens collected during the Challenger 

 Expedition : — 



(1.) April 3, 1875 ; Pacific; surface; lat. 24' 49' 0" N., long. 138° 34' 0" E. ; surf 

 temp. 71°'5 ; half a dozen specimens. 



(2.) April 4, 1875 ; Pacific; surface; lat. 25° 33' 0" N., long. 137° 57' 0" E. ; surf, 

 temp. 69° ; two dozen specimens. 



(.3.) June 17, 1875; Station 237, North Pacific; surface; lat. 34° 37' 0" N., long. 

 140° 32' 0" E. ; surf. temp. 73° ; one hundred specimens. 



(4.) October 19, 1875; Station 287, South Pacific; surface; lat. 36° 32' 0" S., long. 

 132° 52' 0" W.; surf. temp. 57°-8 ; fifteen specimens. 



Plate III. fig. 8, shoW'S the dorsal surface of a specimen of this species irom the 

 South Pacific, October 19, 1875. 



This species is closely related to DoUolum chrenbergi (PI. 111. fig. 5). 



DoUolum tritonis, Herdman (PI. III. fig. 3). 



DoUolum dcnticulatum, Herdman, Trans. Roy. Soc. Edin., vol. xxxii. part i p. 93, 1883. 



Vast numbers of this species were obtained by Dr. John jMurray in the summer of 

 1882 in the North Atlantic, during the cruise of H.M.S. " Triton." In reporting upon 

 the Triton collection of Tunicata in 1883,^ I described these specimens under the name 

 of DoUolum clenticulatum ; but I am now convinced that they do not belong to that 

 sj)ecies, but to one which has not been previously described, so I take this opportunity 

 of changing the name to DoUolum tritonis. For a detailed description and figures I 

 refer to my " Triton" Report ; but it may be useful to note here that the stigmata in 

 the branchial sac commence dorsallj^ behind the third muscle Ijand and extend to the 

 sixth ; while the ventral series terminates anteriorly a little behind the fourth muscle 



1 Report on the Tunicata collected during the cruise of H.M.S. " Triton •' in the summer of 1882, Trans. Roy. 

 Soc. Edin., vol. xxxii. part i. p. 9.'!. 



