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XV. On some Oceanic Entomostraca collected hy Captain Toynhee. 

 By John Lubbock, Esq., F.B.S. Sf L.S. 



Read June 7th, 1860. 



In the present paper is a list containing fifty species of Entomostraca collected by 

 Captain Toynbee in the years 1858 and 1859, and descriptions of fifteen which appear to 

 be new to science, showing how very imperfect is onr knowledge of these interesting 

 creatures. Naturalists, however, are not only indebted to Captain Toynbee for having 

 collected these and many other marine animals, but also, and perhaps in a still higher 

 degree, for having carefully recorded the place, date, and circumstances of each capture. 



Such collections as these are highly valuable ; and as Captain Toynbee fully intends to 

 pursue the same course in his fut;u*e voyages, he cannot fail to obtain results very inter- 

 esting in themselves, and very important, perhaps, in their application to practical navi- 

 gation. 



The collections already made contain numerous Mollusca, Annelids, Zoophytes, and 

 ThalassicoUce, besides Cru.stacea, of which, however, I have as yet confined my attention 

 to the Entomostraca. 



Our knowledge of the oceanic forms belonging to this group is as yet too imperfect to 

 justify us in attempting to draw any general conclusions. The large genera seem to be 

 ubiquitous, — the Calani, however, growing larger in the Northern Seas, while the Pon~ 

 tellcB flourish more in warmer latitudes. 



Some few species are recorded as occurring both in the Atlantic and Pacific Oceans ; 

 but none of the cases are, I think, quite satisfactory, as there has generally been some 

 slight difference between the specimens from the two different oceans. 



Other species appear to be very local ; but until they have been often captured, it would 

 of course be unsafe to come to any conclusion. Many circumstances combine to retard 

 our acquaintance with the geographical distribution of Oceanic species. Certain liues of 

 ocean are repeatedly traversed, while others are almost deserted. The more delicate 

 species can hardly be obtained except when the vessel is going slowly ; so that the calm 

 regions near the line have been examined with (comparatively speaking) considerable 

 care, while the more windy seas of the temperate zones are almost virgin water. The 

 introduction of steam also has of course, in this respect, an unfavourable influence on 

 the study of natural history. 



It may also happen that a species which has been very abundant for some days may 

 suddenly disappear; and yet the change may be no indication of the geographical limit 

 assigned to the form in question, but be caused entirely by some change in temperature, 

 some threatening of a storm, or some other more obscure cause. 



The examination of Captain Toynbee' s collection has impressed me still more deeply 

 with the difficulty, or rather the impossibility, of obtaining satisfactory generic charac- 

 ters. I am of course aware that many naturalists are still inclined to consider genera 



VOL. XXIII. 2 A 



