G6 THE VOYAGE OF H.M.S. CHALLENGER. 



Station 146, December 29, 1873; lat. 46" 46' S., bug. 45° 31' E. ; 1375 fathoms; 

 bottom, Globigerina ooze. 



Station 147, December 30, 1873; lat. 46° 16' S., long. 48° 27' E. ; 1600 fathoms; 

 bottom, Diatom ooze. 



The above cited Monograph of Grube contains a description and figures of a species of 

 Serolis (Serolis tuherculata) which differs from all the species known at that time and 

 from all those already described in the [iresent Report by the characters of the fifth and 

 sixth thoracic segments ; the tergum of the fifth segment, wliich is generally narrower 

 than the preceding ones, is in this species extremely narrow, not measuring more than one- 

 sixth of the diameter of the segment in front, wliile the tergum of the sixth thoracic 

 segment has entirely disappeared : the Challenger obtained two specimens of this same 

 species, Serolis tubercidata, besides examples of four other species which agree witli 

 Serolis tuherculata in the characters just mentioned ; all these species are inhabitants of 

 the shallow waters off the southern and eastern coasts of Australia, and form a well- 

 marked group, agreeing with each other in a number of structural points. These species 

 I have briefly described in my " Preliminary Report," and named as follows : — Serolis 

 ■pallida, Serolis australiensis, Serolis elongata, Serolis minuta, and Se)-olis longicaudata ; 

 all these species, with the exception of Serolis minuta, agree with each other and with 

 Serolis tubercidata in the following points, some of which are peculiar to the group, 

 wliile others again are not confined to the group, but are also to be found in other species. 



They are all of small size ; the females are larger than the males (?). The thoracic 

 epimera are short and closely applied together for their whole length, while the epimera 

 of the two abdominal segments are very short and not prolonged beyond the anterior 

 margin of the caudal shield. The tergum of the fifth thoracic segment is extremely 

 narrow ; the tergum of the sixth segment is obsolete in the middle line, the suture whicli 

 separates it from the succeeding first segment of the abdomen passes forwards and 

 disappears underneath the segment in front {cf. PI. VI. fig. 1) in Serolis tubercidata and 

 Serolis pallida ; in Serolis australiensis, Serolis elongata, and Serolis longicaudata the 

 general appearance of the two last thoracic terga is the same, but a careful inspection 

 shows that the posterior sutures of both segments become obsolete just before the middle 

 line of the body, so that which apparently is the tergum of the first abdominal segment 

 in reality includes also the middle part of the terga of the two last thoracic segments. 

 In Serolis minuta the fifth and sixth thoracic segments are not quite so narrow as in the 

 other Australian species. The fifth segment is divided off by a sutural line which is 

 entirely continuous from one side of the body to the other ; the sixth segment, however, 

 though proportionately somewhat broader, resemljles that of Serolis australiensis, &c., in 

 being fused mesially with the succeeding abdominal segment. In the other Australian 

 species the rostrum is long, reaching beyond the first joint of the anterior pair of 



