ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 189 



epithelial cells, which are continuous -.vith the ciliated cells of the 

 pharynx, bear numerous striated muscular fibrils on their walls — an 

 adaptation to their mechanical function of trituration. 



Rotifera. 



Seasonal Variation in Plankton Rotifera.* — Amongst other 

 plankton organisms dealt with by Wesenberg-Lund in his monu- 

 mental work are the Rotifers, in particular Asplanchna priodonta, 

 Synchseta, Polyarthra, Anursea, and others. The author's results have 

 satisfied him that most plankton Rotifers show a seasonal variation 

 more or less pronounced in response to stimuli due to variations in 

 temperature. These stimuli are a change in the specific gravity of the 

 water and in its viscosity, resulting in an increased rate of sinking at 

 higher temperatures. In response to these stimuli some Rotifers appear 

 to increase the size, and in particular the length of their bodies, whilst 

 others increase the size of their spines or produce protuberances or 

 spines, calculated to counteract the rate of sinking. With regard to 

 Asplanchna priodonta, the author gives tables of measurements showing 

 that in large lakes this species steadily increases in size from May to 

 July, and then rather suddenly disappears. No one will doubt such 

 results, but when the author contends that the small Synchseta ohlonga 

 changes into the large S. pectinata and larger 8. grandis, both widely 

 different in anatomical structure, it is to be feared that few students of 

 the Rotifera will be able to follow him. 



Rotatorian Fauna of Boston. f — C. F. Rousselet gives a list of 

 forty species of Rotifera collected by him in the lake of the Central 

 Park, in Boston (Mass.), U.S.A., one of which, Notholca bostoniensis, 

 is described as new. Besides its small size, it differs from JV. longispina 

 in having only four anterior spines instead of six, and by the fact that 

 the long anterior spine is on the left of the median line instead of on 

 the right. 



Echinoderma. 



Echinoderms of the Coasts of Spain.} — F. Aranda y Millan gives 

 an annotated list of twenty-five Asteroids, eight Ophiuroids, niueteen 

 Echinoids, eighteen Holothuroids, and two Crinoids. 



Genus Linthia in Victoria. § — Gr. B. Pritchard describes a large 

 new species (L. mooraboolensis) of this extinct sea-urchin from Eocene 

 limestone beds in Victoria. The specimen figured was over 1\ in. in its 

 greatest diameter. Three other species are discussed, including Linthia 

 gig as McCoy, formerly referred by mistake to the genus Perkosmus. 



Ccelentera. 



Rhythms in Sea- Anemones. || — H. Pieron has studied Actinia 

 equina in order to discover whether there are definite periodicities in 



• Plankton Investigations of the Danish Lakes. Copenhagen. 1908. 

 t Journ. Quekett Mior. Club, ser. 2, x. (1908) pp. 335-40 (2 pis.). 

 t Mem. R. Soc. Espafi. Hist. Nat., v. (1908) pp. 215-55 (5 pis.). 

 § Proc. R. Soc. Victoria, xxi. (1908) pp. 392-400 (2 pis.). 

 II C.R. Soc. Biol. Paris, lxv. (1908) pp. 726-8. 



