* 
‘On new Species of Marine Mollusca. 269 
the eighth segment. Legs as in P. jormosensis. Wings as 
in P. formosensis, except that the base and the costal cell, as 
well as the subcostal, are dark brown ; there is no pale spot 
beyond the stiema ; the ascending part of Cu, is dark- 
margined, and the celk M, is shortly petiolate. 
EXPLANATION OF PLATE XII. 
Fig. 1. Dicranomyia alticola, sp. n. Apex of 2 abdomen, side-view 
(from balsam preparation). xX 35. 
Fig. 2. Gnophomyia similis, sp. n. Apex of 2 abdomen, side-view 
(from dry specimen). xX 35. 
3. Limnobia nitobei, sp. n. ¢ hypopygium from below. x 35. 
4. Erioptera alboguttata, sp.n. ¢ hypopyrgium from below. x 35. 
5. Tipula rufomedia, sp.n. ¢ hypopygium from below. x 10. 
Fig. 6. Ditto. of right clasper, inner side-view. xX 23. 
7. Ditto. Tip of 2 abdomen from below. x 10. 
8. Tipula rufizona, sp.n. Tip of 2 abdomen from below. x 10. 
Fig. 9. Longurio rubriceps, sp. n. ¢ hypopygium from above (penis 
removed). xX 13. 
Fig. 10. Brithura conifrons, gen. et sp. n. Tip of ¢ abdomen, side-view 
(dry specimen). x 55. 
Fig. 11. Ditto. Apical half of wing. x 4. 
Fig. 12. Brithura crassa, sp.n. Tip of ¢ abdomen, side-view. xX 5°. 
XXIX.— Descriptions of Eight new Species of Marine 
Mollusca from the South Shetland sland. By H. B. 
Preston, F.Z.S 
[Plate XIII.] 
Tue thanks of the author are due to Mr. A. G. Bennet, of 
the Falkland Islands, for the material described in the present 
short paper ; when the difficulties of collecting in what is 
(even in the height of summer) an exceptionally rigorous 
climate, in great discomfort and without adequate apparatus, 
are taken into consideration, it will be readily appreciated 
how much Mr. Bennett was able to accomplish during his 
short stay at Deception Island in the summer of 1913-14. 
Limacina costulata, sp.n. (Fig. 1.) 
Shell discoidal, almost planulate above, with slightly 
exserted apical whorls, extremely thin, white, vitreous, trans- 
parent ; whorls 4, the last large and produced below, trans- 
versely costulate : : ‘umbilicus deep, showing the coiling of the 
whorls ; aperture broadly auriform. 
