378 SUMMAKY OF CUKRENT RESEARCHES RELATING TO 



For if era. 



Vosmaer's Porifera. — The second part of tliis work on sponges, 

 with plates V. and VI., has appeared ; the whole of the text is 

 devoted to the history of the investigation of this subject, and is not 

 yet completed. Plate V. is filled with figures borrowed from Zittel, 

 and some of that palaeontologist's figures, with others from Haeckel, 

 and two new ones are to be found on plate VI. 



Fresh-water Sponges of Russia.*— The 12 nominal European 

 species of the Spougillidie are considered by Dr. W. Dybowski to be 

 reducible, by exclusion of synonyms, to five, viz. S. lacustris auctt., 

 Jiuviatilis auctt., vesia Martens, erinaceus Lieberkiihn, muelleri 

 Lieberkiihn. Of these S2)ecies S. lacustris is the only one recognized 

 by Dr. Dybowski from the Russian Empire ; it appears to extend to 

 near Lake Baikal and to Kamtschatka, although some hook-like 

 appendages upon gemmules of specimens from the latter country 

 throw some doubt on their identity. Besides this is described a new 

 sjiecies, S]pongilla sibirica, from Lake Pachabicha (near Lake Baikal) 

 and a lake in the Caucasus, distinguished from other species by the 

 proportions of the sj)icules and structure of its gemmulte ; also three 

 species of Meijenia, to which, in consideration of his want of informa- 

 tion as to the characters of previously described species, the author 

 with praiseworthy jorudence refrains from assigning sjiecific names ; 

 of these Meijenice, No. 1, from Livonia and Southern Russia, is dis- 

 tinguished by the often, and deeply, cleft margin of the amphidisk- 

 spicules ; No. 2, from Esthonia, Poland, and the Dnieper, has similar 

 amphidisks, but has the skeleton-sjiicules shorter ; in No. 3, from 

 Kamtschatka and Minsk, in Western Russia, the ends of the amphi- 

 disks are deeply cleft into a few large teeth and some or all of the 

 skeleton-spicules are spined ; the sjiecimens from the two localities 

 differ in small points from each other. 



In the last species Dr. Dybowski finds the same phenomenon as 

 Mr. J. G. Waller (in 1878) did in S. Jiuviatilis, viz. the occurrence of 

 both spined and smooth skeleton spicules in the same si)ecimen. As 

 in the genus Luhomirskia in 1880,| so in Spongilla and 3Ieyenia now, 

 the author finds a considerable range of variation in the sizes of the 

 sjiicules, e. g. the skeleton-spicules of S. lacustris may range from 

 •114 mm. to '25 mm. in length, and from "002 to '01 mm. in 

 thickness in different specimens, those from salt water (Gulf of 

 Finland) all bearing smaller spicules than the other specimens; the 

 gemmule-spiculcs of fresh-water examples range from • 024 to • 05 mm. 

 in length, and from '02 to -04 mm. in thickness. Of Spong ilia sibirica, 

 the only specimens of which spicule-measurements are given exhibit 

 a comparatively low range of variation, but here, as in the other 

 species described, the range of variation appears to be intimately 

 connected with the number of localities from which specimens were 

 examined, and in none of the species does the variation of the skeleton- 



» Me'in. Acad. Sci. St. Petersburg, xxx. (1882) No. 10, 23 pp. (3 pis.), 

 t See this Journal, i. (1881) pp. 257-8. 



