280 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Blood System of Malacobdella grossa.* — N. H. W. Maclaren has 

 studied tho blood-vessels of specimens of this form taken from Mya 

 truncata on the Clyde, and finds such differences from the observations 

 of others as to lead to the conclusion that there is local variation. He 

 finds that the " vascular trees " described by von Kennel in the sucker 

 arise from the lateral vessels throughout their length, and also to a less 

 extent from the dorsal vessel. About seven of the trees usually arise 

 from a lateral vessel at either side of the pharynx. Each tree is dis- 

 tinct from its neighbours, and ends blindly ; the trees pulsate slowly and 

 rhythmically in the living animal. In the posterior region the trees 

 are more irregular in shape, and anastomose with one another, forming 

 an irregular system of vessel-commissures. 



Impregnation in Haementeria costata.f — Prof. H. Bolsius faces 

 the difficulty of explaining how the contents of the spermatophore get 

 into the coelomic cavity. The spermatophore is lodged in the vestibule 

 (between the internal and external male genital aperture), but there is 

 no piercing of tissues. The author suggests that by a kind of suctorial 

 action, due to the partly muscular character of the folds (plis) project- 

 ing into the vestibular cavity, the spermatophore is passively emptied, 

 and the spermatozoa are drawn into the coelomic cavity. 



Platyhelminthes. 



SIFresh-water Nemertine.* — W. Zykoff has found in the Volga near 

 Saratow two specimens of a Nemertine, which is possibly identical with 

 Stichostemma grsecense Bohmig. The importance of the find is that this 

 is only the third time fresh-water Nemertines have been recorded in 

 Russia. It is probable that the Nemertine has found its way into the 

 Volga from the Caspian as Dreissensia polymorpha has done, but as yet 

 no Nemertine has been described in the Caspian. 



Avian Cestodes. § — O. Fuhrraann notes that among Vertebrates, 

 birds are most infested with Cestodes, 370 forms being known to occur 

 among tliem. Among birds fewest Cestodes occur in Raptores and 

 graminivorous birds. In the family Acoleinse the author includes four 

 Lew genera Diplophallus, Gyroccelia, Acoleus, and Dioicocestus, in all of 

 which the female sexual opening is absent. In Dioicocestus paronai the 

 sexes are separate, this being the first case described in Cestodes. 



Marine Species of Gyrator.||— Prof. Emil Sekera describes a Tur- 

 bellarian from Trieste which closely resembles the fresh-water species 

 of Gyrator, especially G. hermapJiroditus, but is remarkable for its blue 

 tint. The copulatory organs are also of more simple structure than 

 in the previously known species. The present species is described as 

 G. reticulatus sp. n. 



Syndesmus echinorum Franc.1T — A. E. Shipley obtained a number 

 of specimens of this interesting Turbellarian parasite from Echinus 

 esculentus at Plymouth, and notes some of the peculiarities of structure. 

 The specimens were smaller than those of Francois, varying from 



* Zool. Anzeig., xxiv. (1901) pp. 126-9 (5 fiVs.). 



f Tom. cit., pp. 206-9 (2 figs.). J Tom. cit., pp. 155-6. 



§ Arch. Sci. Phys. et Nat., xi. (1901) pp. 204-5. 



II Zool. Anzeig., xxiv. (1901) pp. 79-81 (2 figs.). 



4 Quart. Journ. Micr. Sci., xliv. (1901) pp. 281-90 (1 pi.). 



