POEAMINirEEA OF THE KERIMBA AECHIPELAGO. 697 



abnormal type and does not bear any very close relationship to other discorbine 

 species, its nearest ally perhaps being B. allomorphinoides Reuss, from which, hoAvever, 

 it differs in the greater coarseness of its perforations, the continuity of its outline, and 

 the comparative bilateral symmetry of the test. It seems also to be unique in its 

 investing wall of shell-substance, which appears to be deposited subsequently to the 

 formation of the chambers as an entirely investing layer of shell, obliterating all 

 sutures and surface-markings. 



This very obscure little form occurs at six Stns. only, one or two specimens at each, 

 except at Stn. 11, where a good many finely developed specimens were found. AVe 

 have also met with it in a dredging made in Apia Harbour (Samoa), 7 fms., where it 

 is more abundant. 



Length (max.) -25 to "30 mm., breadth (max.) -25 mm., thickness '2 mm. 



360. Discorbina chasteri Heron-Allen & Eaiiand. 



Discurhina minutisshna Chaster, 1892, CS. p. 65, pi. i. fig. 15. 

 Wright, 1903, BCD. pp. 174, 175. 

 „ chasteri Heron-Allen & Earland, 1918, CI. p. 128, pi. xiii. figs. 1-3. 



6 Stations. 



The specimens are few in number, but quite typical, and in some cases better 

 developed than is usually the case in tlie British type-specimens. The round form 

 is the more generally distributed, but at Stns. 5 and ] X the round and oval varieties 

 occur in company. At Stn. 12 only the oval type was seen. The best individuals of 

 the round type were observed at Stns. 6 and ■? X, and the best oval at Stn. 12, 



361. Discorbina rugosa (d'Orbigny). 



Rosalina rugosa d'Orbigny, 1839, FAM. p. 42, pi. ii. figs. 12-14. 

 THscorhirta rugosa Brady, 1884, FC. p. 652, pi. Ixxxvii. fig. o ; pi. xci. fig. 4. 



„ Egger, 1893, FG. p. 383, pi. xv. figs. 1-3. 



„ Chapman, 1891, etc., GF. 1893, p. 590, pi. xiii. fig. 10. 



„ Millett, 1898, etc., FM. 1903, p. 703. 



„ Chapman, 1900, FLF. p. 190. 



„ Chapman, 1907, RFV. p. 136. 



11 Stations. 



Occurs at most of the Stns., moderately frequent at some of them, good and quite 

 typical specimens were seen at Stns. 4, 10, and 11. At Stn. ? X a very depressed 

 form, with angular edge (but otherwise typical), was observed. 



362. Discorbina vesicularis (Lamarck). (Pi. LII. figs. 15-18.) 

 Discorhites vesicularis Lamarck, 1804, AM. vol. v. p. 183 ; 1806, vol. viii. pi. Ixii. fig. 7. 

 Discorbina vesicularis Carpenter, Parker, & Jones, 1862, IF. p. 204, pl. xiii. figs. 2, 3. 



Brady, 1884, FC. p. 651, pl. Ixxxvii. fig. 2. 



