170 SUMMARY OF CURRENT RESEARCHES RELATING TO 



were undergoing chemical dissolution like self-digestion. Thus three 

 modes of muscular degeneration were illustrated in the tumour. 



Morphology of Hirudineae.* — N. Livanow gives an account of the 

 anatomy of Acanthohdella pahuUna Grube, and from a consideration of 

 the general characters of the group, he concludes that for differential 

 diagnosis the following are of importance, viz. : — the secondary ringing 

 of the somite ; the development of suckers at the expense of a few body 

 somites ; the typical structure of the muscle-cells ; the development of 

 the mesenchyme and related reduction of coelom ; the development of 

 a peripheral and subcutaneous ccelom ; the differentiation of ganglion- 

 cell clusters in the central nervous system ; the differentiation of endo- 

 dermal gut into a middle and posterior section ; the closed condition 

 of the nephridia coelom-wards, the absence of ciliation in the excretory 

 section, and also the anatomical independence of the funnel apparatus 

 from the excretory section : the development of ovarian sacs in the 

 female sexual apparatus. 



Vascular System of Piscicola.t — W. Selensky has been able, by re- 

 constructing his sections, to present a clear account of the intricacies of 

 the two quite different and separate sets of vessels in this leech, viz. the 

 blood-vascular system proper, and the lacuna-like canals and spaces 

 which represent remains of the secondary body-cavity. 



Platyhelminthes . 



Parasites and Diseases of Fishes. | — James Johnstone gives an 

 account of Cestodes and Trematodes obtained mainly from skates and 

 rays. No new species are described, although the occurrence of varieties 

 is noted, e.g. in Echeneibothrium variabih van Beneden, of which three 

 well-defined forms were obtiiined. An account is given of a fungoid 

 disease attacking FleuronecUs platessa. It was fatal in a number of cases. 

 The fungus, which appears to belong to the Entomophthorinete, occurred 

 in the liver, kidney, and mesenteries ; it is supposed to have gained 

 access to the tank tlirough the liberation of spores from the bodies of 

 insects dying on the surface of the water. An account is given of sub- 

 cutaneous tumours in the dab, PJeuronectes limanda, the cause of which 

 is undetermined. 



Entozoa of British Marine Fishes. § — W. Nicoll gives descriptions 

 of a number of Trematodes from various common shore and food fishes. 

 In a large number of cases known parasites are recorded from new hosts. 

 It appears likely in some cases, e.g. Podocotijh atomon Rud. that the 

 entozoa of a particular fish are determined more by its environment 

 than by its specific nature. Further, in the case of Httoral fishes, 

 dependent on local faunae for their food, the parasites appear to vary 

 with the locality. 



Mollusc-infecting Trematodes. || — M. V. Lebour describes larval 

 stages of three Trematodes, obtained respectively from the common 



* Zool. Jahrb., xxii. (1906) pp. 637-866 (9 pis.). 



t Zool. Anzeig., xxxi. (1906) pp. 33-44 (4 figs.). 



i Proc. and Trans. Liverpool Biol. Soc, xx. (1906) pp. 295-329 (1 pi. and 13 figs.). 



§ Ann. Mag. Nat. Hist., cix. (1907) pp. 66-94 (4 pis.). 



II Tom. cit., pp. 102-6 (2 pis.). 



