ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 33 



5. Iiamellibranchiata. 



Monstrosities in Bivalves.* — F. C. Baker notes that in fresh-water 

 forms these are often due to external accidents, e.g. trampling by cattle. 

 They are commonest about fords and shallows. He describes and figures 

 cases in Lampsilis alata, L. ligamentina, and Unio gibbosus. 



Innervation of Mantle of Pecten.t — L. Boutan describes an inde- 

 pendent " circum-pallial " nerve-centre which has to do with the sensory 

 structures so greatly developed on the periphery of the mantle of Pecten. 

 It is connected with the cerebral and pal lio- visceral ganglia, but if the 

 connecting branches be cut, it retains its functional integrity. It is ten 

 times larger than all the three other ganglia combined. The pallio- 

 visceral ganglia also innervate the mantle, excepting the portion known 

 as the " capuchon cephalique." 



Arthropoda. 

 a. Insecta. 



Morphological Significance of Chitinous Cuticle. J — Hils Holmgren 

 seeks to show that all vertically striated chitinous structures — of one 

 layer or of several layers — in insects, at least, are morphologically and 

 phylogenetically to be interpreted as chitinised and coalescent ciliary 

 hairs. The chief support of his contention is that all the chitin-matrix 

 cells which he has studied have apically a row of blepharoblasts with 

 which the pillars forming the cuticle are in connection. The same 

 disposition of blepharoblasts in relation to a ciliary fringe is well known. 

 The " Stabchensaum," or " Harchensaum," or " plateau striee," e.g. of 

 the gut of Chironomus, is homologous with a ciliary fringe. Thus some 

 light is supposed to be thrown on the absence of cilia in Arthropods. 



Insects of the Drift Line.§ — Laetitia M. Snow has studied the 

 insects along and around the line of drift thrown up by the waters of 

 Lake Michigan in the spring of 1902. The collections included 114 

 species, of which 51 were identified. 



" We have here a little community of food -providers and food- 

 obtainers, whose population varies with the season, the wind (probably), 

 the beach conditions, and the relative abundance of the various forms. 

 For example, we found (1) the occurrence was in succession ; (2) the 

 population increased apparently at times when an off-shore wind was 

 followed by a lake breeze ; (3) it also increased with the temperature ; 

 (4) the greatest numbers occurred on beaches of low gradient and of 

 smooth fine sand ; (5) the abundance of scavenger forms depended upon 

 the abundance of dead herbivorous and predaceous forms and other 

 refuse ; (6) the abundance of predaceous forms depended upon the 

 presence of active scavenger and herbivorous and smaller predaceous 

 forms." 



Calorimetric Measurements in Reference to Pupse of Lepidoptera.|| 

 P. Bachmetjew has made a large number of experiments on the specific 



* Trans. Acad. Sci. St. Louis, xi. (1901) pp. 143-6 (1 pi.). 



+ Comptes Kendus, cxxxv. (1902) pp. 587-9. 



X Anaf,. Anzeig., xxi. (1902) pp. 373-8 (5 figs.). 



§ Amer. Nat., xxxvi. (1902) pp. 855-64. 



|| Zeitschr. f. wiss. Zool., lxxi. (1902) pp. 550-624 (9 figs.). 



Feb. 18th, 1903 D 



