zooLoaY. 7(>9 



determine the systematic values thereof and the best means of classify- 

 ing the groups. "The arrangement of the ambulacral suckers varies 

 with age." The calcareous deposits are much less variable, and in but 

 few cases are there notable differences, according to age or otherwise. 

 The tentacles appear to furnish tlie best difierentiating characters. The 

 combination of DendrocMrofcc introduced by Prof. Jeffery Bell is adopted. 

 Further, the distribution of the tentacles into one or two rows affords 

 good grounds for a division into groups, to be called respectively, "il/o- 

 nocycUa^^ and '■'■ HeterocycUa.^'' A new and systematic monograph of the 

 order is promised by Dr. Lampert. {Biol. Centralhlatt, v. 5, pp. 102-109 ; 

 J. E. M. 8., (2), V. 5, pp. 1007-1008.) 



■ 



WORMS. 



Botifers. 



The relations of the Rotifers. — Much diversity of opinion has prevailed 

 as to the relations of the Eotifers to other classes of the animal king- 

 dom. The subject has been taken up recently by Dr. L. Plate in con- 

 nection with a monograph of the fresh-water rotifers observed by him. 

 He considers that it is clear that " sexual dimorphism is an acquired 

 character." The progenitor of the class ("Archirotator") is supposed 

 to have had a cylindrical body narrower behind, a ventral mouth and 

 dorsal anus, and an aboral tuft of cilia ; the wheel apparatus consisted 

 of two ciliated circlets ; the fore-gut had a chitnious masticatory appa- 

 ratus, and the whole tract was lined by ciliated epithelium ; into its hinder 

 l)ortion opened two unbranched excretory canals and the genital ducts. 

 The nervous system consisted of a dorsal central ganglion, which gave 

 off several anterior and two posterolateral nerves. As to their system- 

 atic position, the Eotifers appear to be of the same stock as the Anne- 

 lids, but they differ from the Trochophore in wanting a ciliated groove ; 

 the hinder circlet of cilia opens into the fore-gut, the aboral tuft does 

 not correspond to the perianal circlet, and the brains are not homolo- 

 gous." {Jenaische Zeitschr. f. Naturwiss., v. 19, pp. 1-120, 3 pi. ; J. B. M. 

 S. (2), V. 6, pp. 76-78.) 



Platyhelminths. 



New York Turhellarians. — An important memoir on the fresh-water 

 Turbellarians occurring especially in Monroe County, New York, has 

 been published by Dr. W. A. SiUimau in the " Zcitschrift filr wissen- 

 schaftliche Zoologie " (v. 41, pp. 48-78, with 2 pi.). Twenty-one species 

 have been recognized, of which a considerable number, it is supposed, 

 are common to America and Europe. Dr. Silliman considers the groups 

 named Khabdocosla, Tridada, Polycloda, and i!«remertinea to be of approx- 

 imately equal value and representing four "orders" of Turbellariiius. 

 H. Mis. 15 49 



