THE BllACHIOPODA OF THE SCOTTISH NATIONAL ANTARCTIC KXPKD1T1ON. 155 



south-west of the South Shetland*, the possibility of the large size being influenced by 

 shallowness in depth cannot be determined. 



.The specimens obtained by this Expedition are very oval in shape, like the. Scotia 

 Bay examples, and, as in the hitter, they also possess a curious labiate prolongation of 

 the foramen over the dorsal umbo (see fig. 1, and UEHLERT, 1908, pi. i.), which dues 

 not appear to be present in the South Georgia examples or in normal specimens of 

 /,. uva from Burdwood Bank and neighbouring stations. 



The shells, too, possess a greater vertical diameter owing to the rotundity of their 

 valves, and the angular appearance of the lateral margins, present in L. ura, is absent 

 (compare BLOCHMANN, 1912, pi. i.). 



To the above-mentioned differences must also be added an important variation in 

 the composition of the shell-mosaic and the perforations of the test, based upon a study 

 of the Scotia Bay examples. 



Here the number of pores per square millimetre in specimens Nos. 2 and ."> is 96 

 to 128. These examples are, unfortunately, too opaque for a detailed study of the 

 mosaic. 



An examination of different portions of both valves of the young example No. 4, 

 shows a range from 88 to 128 pores per square millimetre. The shell-mosaic, is here 

 clearly visible and consists almost throughout of a well-developed imbricating structure, 

 with scarcely any trace of the irregular character exhibited in young examples of 

 L. urn (2'75 and 5 mm. in length) from the Burdwood Bank material. The number 

 of pores in the latter specimens ranges from 200 to 256 per square millimetre. 



It may be of some interest here to call attention to a number of fossil forms of 

 Terebratulidre which have recently been described from the immediate neighbourhood 

 of Graham Land, to the south-west of the South Orkneys. 



In the report on the Antarctic fossil Brachiopoda collected by the Swedish South 

 Polar Expedition, BUCKMAN (1910) describes, under the generic name of Terebratula, 

 several very interesting forms, which appear to me to have some bearing on the recent 

 species now inhabiting the neighbouring seas. 



Amongst the coarsely punctate series three forms are described, two of which are 

 referred to previously described fossil species; the other, owing to its fragmentary 

 character, is not specifically determined. 



One of these forms is referred by BUCKMAN to Terebratula bulbosa, Tate (a species 

 met with in Australian Tertiary strata), with certain slight modifications in the 

 description to suit the Antarctic specimens. 



Without a comparative study of the Australian and Antarctic forms it is impossible 

 to say if this identification is correct or not, but it appears to me possible that the two 

 forms are in no way related to each other. 



BUCKMAN'S figure* (pi. iii. fig. 7), which is a restoration, and his revised 

 description present, in my opinion, striking resemblances, so far as external appear- 



* Tlie Initiation of the fomnirii li:i IK.-CII overlooked by tlit: ttrlist. 

 (HOY. SOC. EDIN. MANS. VOL. XLV1II., 377.) 



