140 SUMMARY OF CURRENT RE8EARCIIES RELATING TO 



7- Brachlopoda. 



Brachiopoda.* — Dr. F. Bloclinianu's observations on tlic structure 

 of these uuinials have corroborated Hancock's views as to the existence 

 of a contractile heart (which contains branching muscle-fibres) and of 

 the dorsal vein over the gut and the genital arteries, which are only 

 sjiaces within the mesentery. He disagrees, however, with Hancock 

 as to the "afferent brachial canal" of the latter, which is really the 

 pupra-oesoi)hageal brachial nerve. Further, the plexus which Hancock 

 describes as circulatory, are really branching and anastomosing con- 

 nective-tissue-cells. A brachial vessel, sending ofl' vessels to the 

 cirrhi, runs along the whole length of the brachial sinus behind the 

 oesojdiagus connnunicating by paired branches with the ojsophagcal 

 blood-sinus, and so with the heart. 



Crania nvomala has no heart, but shows numerous enlargements 

 on the " vein." A heart is seen in Argiope, — two occurring in A. 

 neapolitana. 



In Crania there are two pairs of straight and throe pairs of oblique 

 muscles, together with an unpaired oblique nuiscle. The mantle- 

 border is smooth, and there is a median and posterior anus. 



As regards the nervoxis system of Braclii(q)oda, Blochmann agrees 

 generally with Van Bemmelen, cxcc])t in the histology. In Crania 

 anomala there is only a narrow fibrillar commissure in the place of 

 the supra-ccsophageal ganglion. 



Arthropoda. 

 o. Insecta. 



Cameron's British Phytophagous Hymenoptera.f — In the second 

 volume of his monograph Mr. P. Cameron continues the description 

 of the species of saw-flies (which is to occupy two more volumes), 

 dealing only with the species of a single tribe or sub-family, the 

 Nematina. This group, although not so extensive as that of the 

 Tenthredina, which were treated of in the first volume, is the one 

 which presents the greatest difiiculties for the descriptive entomo- 

 logist, as it includes the great genus Nematus, of which Mr. Cameron 

 here records 107 British species, many of which are closely allied — 

 in fact so closely that, as in the case of the Lepidoptera, it seems to 

 be necessary in some cases to rear the species, the larvte presenting 

 decided differences when those between the perfect insects are obscure. 

 The whole number of British species of the group is only 132. 



In an appendix the author indicates certain species to be added to 

 genera treated of in his first volume, and also offers some important 

 remarks upon the subject of parthenogenesis as occurring among the 

 saw-flics, as to which he says, " there seems to be no doubt that the 

 phenomenon is quite common." 



» Zool. Anziig., viii. (1SS5) pp. 1G4-7. 



t Cameron, P., 'A Monojrrapli of tlio British r]iytoph;ip,rius Ilvmenoptera 

 ( Tnithrcdo, Shrx and C'i/hv-.s L.), vol. ii., 2:5:5 pp. and 27 pis., Syo, Hay Society, 18S5. 

 See Ann. aud Mag. Nat. lliat., xv. (18S5) pp. 4KJ 7. 



