18 Mr. P. H. Gosse on Asplanchna priodonta. 



long to Spain, two more species belong to the alpine flora, two 

 to the warmer parts of France and Italy, one to Hungary and 

 Greece, and three to western Asia between Syria and the Cau- 

 casus. 



It is worthy of remark, that here, as in many other natural 

 groups, e. g. the Pilosella section of the genus Hieracium, the 

 hairy clothing which is common to nearly all the species is found 

 to be most abundant and of a more rigid character in the spe- 

 cies which inhabit the continental region, farthest removed from 

 the influence of the coast climate of the Atlantic. 



II. — Description 0/ Asplanchna priodonta, an animal of the Class 

 Rotifera. By Philip Henry Gosse, A.L.S., M.M.S. 



[With two Plates.] 



The extreme interest of the discovery by Mr. Brightwell (re- 

 corded in the 'Annals^ for September 1848) of the dioecious 

 character of a species of the class Rotifera, induces me to men- 

 tion the fact that a second (if not a third) species of the same 

 genus has fallen under my notice. 



In the course of a series of investigations on the Rotifera pur- 

 sued during the last year, I received through the kindness of 

 Edmund E. Bowes, Esq., water from many of the ponds of Wal- 

 thamstow and its neighbourhood. A species of this genus was 

 abundant in one of these in August, which in several particulars 

 differed from Mr. Brightwell's ; but it needs further examination 

 before it can be established. 



On the third of the present month (May 1850) I took many 

 specimens of a species, which is certainly distinct from Mr. Bright- 

 well's, and I think also from the Walthamstow one. I dipped 

 them from the margin of the Serpentine in Hyde Park, close to 

 the house of the Humane Society. A few days later I obtained 

 a single individual of the same species from the lake in front of 

 Kensington Palace. 



Taking the elaborate description by Mr. Dalrymple in the 

 Phil. Trans, for 1849, as the standard of the first detected spe- 

 cies, I find that of the Serpentine to differ in several important 

 particulars. It is not more than, half as large, adult females 

 averaging about ^^^ of an inch in length, and none that I saw 

 measuring more than ■^-^. The. jaws are broader, are rather 

 hooked or falcate at the tip than uniformly curved, and instead 

 of the projecting tooth on the inner side they have this edge 

 minutely serrated, with the tip forming two curved longer teeth. 

 Each mandible carries a style of spine, proceeding from its back. 



