202 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Turbellarians of Mississippi Basin. — Ruth Higley {Illinois BioL 

 Monographs, 1918, 4, 1-94, 8 pis.). In swiftly flowino^ streams where 

 a rocky bed furnishes a sheltered place of attachment, Planarians and a 

 few creeping Rhabdocoels find a suitable habitat. For most of the free- 

 swimming species, ponds and temporary puddles are best. They afford 

 a protected retreat and also a feeding-ground in the masses of filamentous 

 algis, and a source of food in the associated animal comumnities. The 

 response to the presence or absence of oxygen and carbon dioxide is 

 more precise than that evoked by any other stimulus. The reaction 

 to light varies in different species ; in most instances it is negative, 

 though not definitely so. Response to temperature is general or diffuse, 

 rather than to a localized stimulus, such as the seasonal change in the 

 condition of the water. Since nourishment is obtained mostly from dis- 

 integrating protoplasm, the food relationships are very simple, and 

 although nearly defenceless the Turbellarians appear to have few 

 enemies. New species of Stenostoma, Macrostoma, Dalyellia, Strongylo- 

 stoma and Merostoma are described, and the precise conditions under 

 which they live are noted. J. A. T. 



Intestinal Helminths in Indians in Mesopotamia— C. L. Boulexger 

 {Parasitologij, 1920, 12, 95-7). Out of 1,180 individuals examined 

 1 • :} p.c. had Teenia saginata ; 2 p.c. Hymenolepis nana ; 5 ' 2 p.c. Ascaris 

 lumhricoides \ 0*08 p.c. Oxyuris vermicuJaris \ 18*5 i^.c. Anchylostoma 

 (or Ancylostoma) dnodenah and Necator americanus ; 1 • 2 p.c. Tricho- 

 strongylus sp. ; ' 5 p.c. Strongyloides stercoralis ; and 5 p.c. Trichuris 

 trichiurus. Attention is drawn to the fact that Hymenolepis nana 

 seems to be the commonest tapeworm met with among Indians. 



J.A. T. 



Nemertea. 



Sex Dimorphism in Nemerteans. — W. R. Coe {Proc. Amer. Soc 

 Zool. in Anat. Record, 1920, 17, 852). Several secies of Necione- 

 mertes show in the mature males a pair of lateral muscular tentacle-like 

 appendages immediately behind the head. The testes, which are limited 

 to the head region, have a powerful musculature for the forcible ejacula- 

 tion of the sperms. The females are so different that they have been 

 referred to a separate genus. It is probable that the " tentacles " are 

 both tactile and prehensile. They may serve to hold the females during 

 insemination. J. A. T. 



Coelentera. 



Mesenteries in Urticina crassicornis. — James F. Cemmill {Proc. 

 Zool. Soc, 1919, 45;)-7). The adult Urticina is remarkable as having 

 its mesenteries and tentacles apparently arranged in ten-cycled symmetry, 

 and on that account has been placed by various authors among the 

 Paractinea3. It is, however, a Ilexactinian, with the arrangement of the 

 mesenteries modified during early growth. The author explains how 

 this comes about. " J. A. T. 



