No. VI.— ISOPODA FKOM THE INDIAN OCEAN AND BRITISH 



EAST AFRICA. 



By the Rev. Thomas R. R. Stebbing, M.A., F.R.S., F.L.S., F.Z.S., Hon. Fellow 

 of Worcester College, Oxford, and Hon. Memb. New Zealand Institute. 



(Plates 5—11.) 



Read 16 December, 1909. 



In two of the earlier reports specimens collected by Mr Cyril Crossland in British 

 East Africa have been discussed in combination with those obtained by Mr Stanley 

 Gardiner from the Indian Ocean in 1905. This procedure, in itself by no means un- 

 satisfactory, I am following not quite by intention. The report on Mr Crossland's Isopoda 

 from the Red Sea was already out of my hands before I became aware that specimens 

 which he had collected on a previous expedition at Zanzibar and Wasin in 1901 — 2 were 

 included with those due to the voyage of the " Sealark." Though the distances are 

 considerable between some of the collecting stations of the three expeditions, there is 

 probably little to interfere with the wide distribution either of the free-swimming Isopoda 

 or of those partially parasitic on fishes. It is reasonable, therefore, when circumstances 

 permit it, to group together in a single survey the gatherings from the extensive area 

 with which these exploring agencies have been concerned. 



Only four out of the thirty-four species here under discussion are of relatively 

 important size. Many of them are rather perplexingly small. Several are represented 

 in the collections by single specimens. 



The diversity, however, is not only specific, seeing that they are spread over five 

 tribes, thirteen families, and no fewer than twenty-nine genera. Four of the genera and 

 fourteen of the species are set forth as new. Among these Kallia/pseudes maikroihrix 

 from Wasin, Pontogelos aselgoJceros from Mauritius, representatives of new genera, and 

 the new species Apa/nthura xenocheir from Eginont Reef, have rather striking peculiarities 

 which will repay attention. 



Besides the Isopoda Mr Crossland's collection included one gathering of Leptostraca. 

 At Wasin from a depth of ten fathoms he obtained six specimens of Parunehalia hmgipes 

 (v. Willemoes Suhm). By Professor Sara in the "Challenger" Reports, vol. xix., 1887, 

 and by Dr J. Thiele in the " Valdivia" Reports, vol. viii., 1904, this member of the family 

 Nebaliidse has been treated with admirable fullness of description and illustration. As 

 the Wasin specimens comprised none of the rare males, there is no need here to add 

 anything further to the literature of the subject. 



11—2 



