(JU) 
Or 
(‘> 
THE REY. T. R. R. STEBBING ON 
ISOPODA GENUINA. 
Tribe FLABELLIFERA. 
Fam. SPH HZROMIDZ. 
1847. Spheromide White, List of Crustacea in Brit. Mus., 
p. 102. 
1910. 43 Stebbing, Ann. 8. Afr. Mus. vol. vi. p. 426. 
Gen. ExospH#RomA Stebbing. 
1900. Hxospheroma Stebbing, Pr. Zool. Soc. London, p. 553. 
1905. be Hansen, Quart. J. Microsc. Sci. vol. xlix. 
PpalOs. ils: 
ESOS e Stebbing, Ann. 8. Afr. Mus. vol. vi. p. 428. 
This genus is placed by Hansen in the section Spheromini of 
his group Spherominz hemibranchiate, 
EXxosPHAROMA CALCAREUS (Dana). (PI. IT.) 
1853-55. Spheroma calearea Dana, U.S, Expl. Exp. vol. xiii. 
p..776, pl. 52, fig. 2 a-c. 
1891. Spheroma - Dollfus, Miss. du Cap Horn, Crust. 
p: 64, pl. 8a. figs. 7, 7a, 7 0. 
1913. Hxospheroma coatsii Tattersall, Tr, R. Soc. Edinb. vol. xlix. 
p. 885, figs, 3, 4. 
This is one of the species which are now in rapidly increas- 
ing number perplexing the systematist by their variability. A 
comparison of the figure supplied by Dana in 1855 with 
Dr. Tattersall’s in 1913 would scarcely suggest a suspicion of 
specific identity. As it is, probably some allowance must be 
made for a little want of detail in Dana’s sketch. But Dollfus, 
who had at command several specimens, explains that the 
granules and tubercles on the general surface and the double 
crest on the pleon sometimes disappear, leaving a smooth form 
such as Dana represents. Dr. Tattersall, describing and figuring 
an adult female and a young form, from Dr. Bruce’s Scottish 
Antarctic Expedition, noted the comparative infrequency of 
tubercles in the young, with other differences, but he had no 
mature male to test for sexual difference. This deficiency I have 
been able to supply from Mr. Vallentin’s collections. The 
specimen figured was 13 mm. long by 7 mm. broad. A female, 
16 mm. long, containing a great number of eggs, was taken by 
Mr. Vallentin at low ebb of a spring tide in Stanley Harbour, 
Nov. 12, 1901. Other specimens, taken at Rapid Point, low 
water, Jan. 30, 1911, comprise a male 19 mm. long by 10 mm. 
broad at the sixth pereon segment. This capture corroborates 
the statement by Dollfus that he had observed males which were 
strongly granular and others almost smooth. Variation also 
affects the colour, at least to judge by preserved specimens, 
