194 "TERRA NOVA" EXPEDITION. 



The largest specimens in the collection are, one example from Station 316 : 

 Length, 21 ; width, 15; thickness, 11 '5 mm., and one from (Station 338: 

 Length, i' 1 8 ; width. 14' 7 ; thickness, 11 '7 mm. Both are elongate-oval in outline, 

 and are like the smaller specimen figured by Eichler [1911, pi. 42, figs. 4 a-l>]. 

 The example from Station 316 has much coarser growth-lines. 



The general characters of this species have been described in detail by Blochmann 

 and Eichler, who state that it belongs to the group of Liothyrinse characterised by the 

 presence of certain spicules at the bases of the cirri (Cirrensockeln). 



From a study of the "Terra Nova" specimens I am able to add some further 

 particulars. 



In general outline, the shell is pyriform, longer than broad, reaching its greatest 

 breadth a little in front of the middle. In a few cases the outline is more ovate. 

 Both valves are about equally inflated, and on their outer surface very delicate in- 

 cremental lines are visible. In addition the surface is ornamented by extremely fine 

 radial lines, visible when the shell is held in a particular position. These lines, or 

 strife, are not mentioned by Blochmann and Eichler ; they are apparently coincident 

 with the radial arrangement of the punctse. 



In the majority of the examples the anterior commissure forms a broadly flattened 

 arch dorsalwards, the shells being incipiently uniplicate. A few specimens not 

 necessarily the largest are more dorsally uniplicate. 



The beak is short with rounded flanks ; the pedicle-collar is distinct but short ; 

 and there is a labiate prolongation of the rim of the foramen extending in some 

 specimens over the conjoined deltidial plates. 



The interior of the dorsal valve possesses a thin, thread-like, mesial septum, but 

 there are no indications in this valve, nor in the ventral valve, of the radiating 

 grooves which serve for the attachment of the pallial sinuses. 



In type of cardinalia and brachidium it is closely allied to L. tint, and, like that 

 species, it pertains to the genus Liothyrella and not to Liothyrina. 



The test is thin and finely punctate. In the specimens selected for examination 

 (from Station 339) the number of puuctse per square millimetre ranges from 90 to 128, 

 on the inside of the ventral valve, about the middle. Eichler [1911] gives the range 

 from 120 to 150 per square mm. The shell-structure is exactly like that figured by 

 Eichler [1911, pi. 43, fig. 20]. 



The occurrence of this species in the Ross Sea area is of great interest, as it was 

 hitherto only known from the type station in the Eastern Antarctic Kaiser Wilhelm II. 

 Laud, 210 fathoms ("Gauss" Expedition). It will probably be found to have a 

 circumpolar distribution. Liothyrina hlorfimanni, described by myself in 1912 [Jackson, 

 1912, p. 378, pi. i, figs. 4-8] from specimens dredged by the "Scotia" Expedition, in 

 1,410 fathoms, off Coats Land, Antarctica, presents some slight resemblance to L. unf- 

 (tr<-/ irn. It possesses a slight mesial septum in the dorsal valve; the surface of the 

 valves is microscopically striated ; and it has a short pedicle-collar. It differs, however, 



