ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 45 



INVERTEBRATA. 



MoUusca. 



y. Gastropoda. 



Experiments with Physa gyrina." — Elizabeth Lockwood Thompson; 

 has thoufjjht out a modification of Pavlov's method of testing the power 

 of association-forming. When the snail, gliding under the surface 

 film with foot and mouth up, is touched close to the mouth with a 

 particle of food, there follows a repeated opening and closing of the 

 mouth. This food-stimulus was synchronously associated with pressing 

 on the foot with a clean glass rod. After 60-110 trials, the snails gave 

 the mouth response when there was synchronous application of the 

 two kinds of stimuli. After forty-eight hours' rest the snails thus 

 "trained" were tried with the foot-pressure stimulus only, and responded 

 with the mouth reaction. The association had been established. It 

 persists for a maximum of 91! hours, and then suddenly ceases. An 

 interesting waning of response in some of the series of trials was 

 indicated by a reduction in the number of mouth movements. This 

 indicated that the snails were becoming adapted to the stimulus which 

 is not followed by its wonted reward. Interesting experiments with a 

 very simple labyrinth anchored to the foot of the tank showed that the 

 snails have no power of learning how to deal with it, how to take the 

 right path leading to air instead of the wrong path which led to no^ 

 reward, but sometimes to the punishment of an electric shock. The 

 most that they learned was to associate the warning stimulus of an 

 irritating hair with the ensuing punishment of a shock, for 15 p.c. out 

 of a total of 930 trials showed a turning from the wrong to the right 

 path when the warning stimukis of the hair operated. But "selective '^ 

 ability was a-wanting. 



Philippine Species of Amphidromus.f — Paul Bartsch has made a 

 study of the Philippine species of this genus of land snails, which 

 presents some interesting zoo-geographic problems. Thus some of the 

 groups — e.g. A. qiiadrasi — show a northward migration from Borneo 

 into the Philippine Archipelago. The group A. maculiferus divides 

 up into a series of geographic races, " beautifully accounted for by the 

 separate habitats which they occupy." 



Arthropoda. 



Arthropods from Burmese Amber. | — T. D. A. Cockerel! describes 

 from a single large piece of amber— a Millipede, Polyxeinis burmitkus 

 sp. n.; an Acarine, Ckeyletus biirmiticus sp. n.; a Dipteron, Winnertziola 

 burmitica sp. n. ; a beetle, Dermestes larvalis sp. n. ; and two Hymenop- 

 tera, Scleroderma (?) quadridentatum sp. n. and Apenesia ehctriphila sp. n. 

 The amber was found in clay of Miocene age, but was derived from 

 elsewhere, and may be much older. 



* Behaviour Monographs, Cambridge, Mass., ill, No. 3 (1917) pp. 1-89 (8 pis. 

 and 12 tables). 



t U.S. Nat. Museum, Bull. No. 100 (1917) pp. 1-47 (22 pis.). 

 I Psyche, xxiv. (1917) pp. 40-5 (6 figs.). 



