104 Mr. H. J. Carter on the 



Lubomirskia jpapyracea. 



Lubo7nirskia papyracea, n. sp. (No. 32, p. 33, taf. i. fig. 7 &c.). 



Papyraceous in thinness, with smooth shining surface. 

 Structure very soft. Colour white. Skeleton-spicule thick 

 (seven times longer than broad), curved, cylindrical, round at 

 the ends, thickly spiniferous throughout (PI. VI. fig. 22) . 



Loc. Lake Baikal. 



Largest skeleton-spicule 0"144 by 0*018 millim. Paren- 

 chyma-spicule a very small smooth acerate. 



Ohs. The " parenchyma-spicule " appears to be the same in 

 each of these species, and therefore is probably merely an early 

 form of the skeleton-spicule, and not a " flesh-spicule," which 

 it is hardly to be supposed would be the same in all four. 



Ohservations. 



Besides the new species of freshwater sponges in Lake 

 Baikal, Dr. Dybowski mentions the occurrence of Spongilla 

 lacustris in a small lake at its western end, called the " Pacha- 

 bicha See," together with a new species, viz. 8. sihirica (No. 

 32, p. 66), which is not described; also the occurrence of 

 Spongilla lacustris in the Goktscha See in Transcaucasia, in 

 the Dnieper, Minsk, Livonia, and aboutWarsaw and Charkow ; 

 also Ejpliydatia [Spongilla) jluviatilis in Livonia, Warsaw, 

 and Charkow ; besides Trachyspongilla erinaceus (No. 28 and 

 No. 32, Taf. 4. fig. 13 a), Spongilla erinaceus (No. 32, p. 33), 

 '? Spongilla erinaceus^ Ehr. 



Thus it is evident from what has been above stated that 

 freshwater sponges have been found in many parts of Europe, 

 in Asia, and in the two Americas ; but, to my knowledge, no 

 notice has been made public of their occurrence in Africa; 

 still it may be fairly inferred that new species will be dis- 

 covered there as well as elsewhere; and a yet further infe- 

 rence may be drawn, viz. that we are only on the threshold of 

 our knowledge of the extent and varieties of the Potamo- 

 spongida generally, so vast are the freshwater areas that have 

 not been explored for this purpose. 



Ehrenberg in his ' Mikrogeologie,' 1855, Taf. 1-12, repre- 

 sents many amphidisks (birotulates) which he found in 

 " freshwater deposits " of various parts of the world, several 

 of which are quite different in form from those with which we 

 are acquainted. 



Lastly, I would observe that, although I have endeavoured 

 to make the above communication immediately useful, it is 

 by no means intended to supply what can only be obtained by 

 a careful perusal at leisure of all that has been written on the 

 subject, especially that to which I have referred. 



