446 SUMMARY OF CURRENT RESEARCHES RELATING TO 



general occurrence. These larvse are evidently the agents of infection 

 of new hosts, where they give rise to plasmodia. It is suggested that 

 the vermiform individuals (agamontes) in Dicyemids correspond to the 

 plasmodia in Orthonectids, and the infusoriform individuals (herma- 

 phrodites ?) correspond to the sexual individuals of Orthonectids. 



Rotifera. 



Retro-Cerebral Organ in certain Rotifers.* — P. Marais de Beau- 

 champ describes a structure lying dorsal to the " brain " in representa- 

 tives of Euchlaninae, Rattulinse, Colurinae, Gastropodinse, and Notom- 

 matinae. It is a glandular organ, bifurcated in front at least, with two 

 apical apertures, and forms a secretion which stains during life with 

 neutral-red. In Notommata and related forms it is intimately connected 

 with the brain and eye, and probably has a secondary sensory func- 

 tion. Its secretion has the form of bacteroid granules. In Copeus and 

 Eosphora there are two auxiliary cells, which seem to be derived from 

 the brain. 



New Rotifer s.f — James Murray figures and describes Callidina 

 vesicularis, a new Bdelloid Rotifer from moss, characterised in par- 

 ticular by the possession of f teeth in the jaws, six pairs of very large 

 and prominent vibratile tags, and two blunt processes in first foot- joint, 

 and small spurs, separated by wide interspace. 



James Murray f further describes, in a " List of Rotifera of the Forth 

 Area," Stephanops microdactylus, a minute new species having a single 

 long style on the dorso-posterior part of the body, and a long narrow 

 foot ending in two very minute toes. 



Raffaele Issel § describes Notommata nqjas var. termalis, a new 

 variety which the author found living in various hot springs in Italy in 

 company with the very rare Euchlanis plicata Levander, at temperatures 

 ranging from 45°-87° C. No other species of Rotifers were found in 

 these thermal waters. 



Echinoderma. 



Antarctic Echinoderms.|| — R. Kcehler makes a preliminary report 

 on the forms collected by Charcot. They are very different from those 

 of the ' Belgica ' or ' Southern Cross ' collections. The Asteroids are 

 peculiarly interesting, e.g. Ripaster charcoti g. et sp. n., an Archiasterid 

 characterised by the delicacy of the marginal plates, and Cryaster antarc- 

 ticus g. et sp. n., remarkable in the complete absence of a dorsal skeleton 

 - — which requires a new family, Cryasteridese. The author notes the 

 absence of any similarity with Arctic Echinoderm fauna. 



Holothurian Spicules. 1[ — W. "Woodland gives an account of the 

 development of the spicules of Cucumaria, of the mode of deposition of 



* Comptes Rendus, cxli. (1905), pp. 961-2. 

 t Journ. Quekett Micr. Club, ix. (1906) pp. 259-62 (1 pi.). 

 X Ann. Scot Nat. Hist., 1906, pp. 89-93 (5 figs.). 

 § Atti Soc. Ligustica Sci. Nat. e Geogr., xvii. (1906) pp. 1-72 (1 pi.). 

 || Comptes Rendus, cxlii. (1906) pp. 113-15. 

 i Quart. Journ. Micr. Sci., No. 196 (1906) pp. 533-59 (3 pis.). 



