42 M. Van Beneden on a new genus uf Cestoid Wwm. 



American specimens of C. virginiacus are somewhat larger 

 than the Indian and Maltese ones. Both varieties however have 

 been recently found by Capt. Drummond in Bermuda. In a 

 list of the Birds of Bermuda by Mr. H. B. Tristram, which is on 

 the point of being published by Sir W. Jardine in his ' Contri- 

 butions to Ornithology/ these two varieties are regarded as di- 

 stinct species, as appears from the following passage : " No. 46, 

 Charadrius marmoratus [i. e. virginiacus^^, American golden 



plover. No. 47, Charadrius ?, an unnamed species smaller 



than the American and perfectly distinct. Not unfrequent here. 

 It has been also found in Malta by Capt. Drummond, 42nd 

 R.H." 



VII. — Notice of a new Genus of Cestoid Worm. By M. P. J. Van 

 Beneden*. Communicated by J. T. Arlidge, A.B., M.B., 



(Lond.). 



The researches of M. Beneden in the lower forms of animal 

 existence have rightly secured him the reputation of an original, 

 diligent, and careful observer ; and every communication there- 

 fore from him deserves the attention of the naturalist. This 

 leads us to give an abstract of his notice of a new genus of Ces- 

 toid Worms, and of a proposed amended arrangement of them. 



M. Beneden discovered the new entozoon at the commence- 

 ment of the spiral intestinal lamina of the skate, in company 

 with other worms of the genus Bothriocephalus. Before enter- 

 ing on its description, he would premise that, as the Cestoidea go 

 through several phases of existence, a species is not represented 

 by the adult state only, but by its several successive generations 

 by gemmation, and of which the last only is furnished with 

 sexual organs ; and that it is consequeritly necessary to describe 

 separately those various phases and to give them special names. 



Thus the first stage of existence may be called the scolexoid, 

 being that of the scolex or young worm on its escape from the 

 ovum ; the second, the strobiloid, from the word strobilus of 

 M. Sars, designating the analogous stage of the Medusa; the 

 third and last, the proglottoid, from the term proglottis, applied 

 by M. Dujardin to the separated joints of the Cestoidece. 



Owing to the striking peculiarities of the newly-discovered 

 worm, M. Beneden has felt it necessary to constitute a new ge- 

 nus, of which it is at present the only example. This new genus 

 is designated Echinobothrium, and presents the following cha- 

 racters : — 



First, or Scolexoid generation, unknown. 



* Extracted from vol. xvi. of the ' Bulletin de 1' Academic Royale de 

 Belgique.' 



