ZOOLOGY AND BOTANY, MICROSCOPY, ETC, 341 



of types, representative of all the orders of fishes have been carefully 

 studied as regards the lateral muscle, the posterior muscles, and the 

 anterior muscles of the shoulder-girdle, and the adductor and abductor 

 of the pectoral fin. A generalized comparative survey is submitted. 

 The author's object in elucidating the mnsculature of the fore-limb of 

 fishes was to clear the ground in approaching afresh the problem of the 

 evolution of the pentadactyle limb. J. A. T. 



Feeding Habits of Young Fishes.— Maeie V. Lebouk {Joimi. 

 Marine Biol. Assoc.., 1919, 12, 9-21). There are great differences in the 

 way various species feed. Some stalk selected food, others apparently 

 eat the first thing that comes. Some feed at all times, others only at 

 night. Some eat very little at one time, others as much as they can 

 get. Some are very shy, others snap at once. Of all those observed 

 the whiting is the greediest, and very clever at selecting the best. 

 The pollack comes second. These stalk their food, usually Copepods, 

 coming up from behind and giving a sure sideways dart, so that the 

 Copepod is swallowed head foremost. The young of the Ballan Wrasse 

 {Labrus bergylta) are slow and stupid ; the species of Solea very alert. 

 Young lumpsuckers, fixed to the glass sides of the aquarium, would 

 instantly unfix when food was near. Selecting something specially 

 attractive, they would chase it and quickly swallow it. A post-larval 

 angler, 8 • 5 mm. long, showed large and extremely brilliant blue eyes. 

 The anterior portion of the dorsal fin bears four long processes ; the 

 pectoral fins are large and with lobed processes ; the pelvic fins are 

 almost as long as the body. The darting movements are very rapid, 

 the pelvic fins looking like wings, J. A, T, 



Function of Swim-bladder. — A, Boutan {Gomptes Rendus Acad. 

 Paris, 1916, 163, 529-31), Each species of Teleostean fish has its 

 appropriate depth at which it is in hydrostatic equilibrium. By the 

 absorption or secretion of gas in the swim-bladder the fish maintains 

 itself automatically at its appropriate depth. The absorption or secretion 

 is the result of a physiological reaction which the author discusses. 



J. A, T. 



INVERTEBRATA. 



Mollusca. 

 y. Grastropoda. 



Spermatogenesis of Pulmonate Gastropods. — J. Bronte Gatenby 

 {Quart. Journ. Micr. Sci., 1919, 63, 197-258, 3 pis,, 3 figs.). Eight 

 species of Pulmonates, species of Limax, Arion, Helix and Testacella, 

 have been studied, A new set of plasmatic bodies, the post-nuclear 

 bodies, have been discovered. They resemble mitochondria in their 

 size, but differ in staining affinities. They ultimately form a plate at 

 the rear of the spermatid nucleus. It is large at first, but shi'inks 

 synchronously with the shrinkage stages of the nucleus. These post- 

 nuclear granules appear to become non-staining during the maturation. 



The mitochondria of all the Pulmonates studied are of much the 



