183 



1. Larva inclosed in a gall and in an imperfect silken cocoon, 

 and pajising to the pupa state without moulting its skin. 



2. Larva exposed, and not inclosed in a cocoon ; casting off its 

 penultimate larva-skin ; and becoming a naked pupa in the ground 

 without moulting its last skin. 



3. Larva (and pupa) remaining inclosed in the penultimate 

 larva-skin ; and becoming a coarctate pupa without casting off its 

 last larva-skin. 



For the specific characters of these and of some other species 

 of Cecidomyia^ illustrated by figures, the elaborate descriptions 

 by Dr. Asa Fitch may be consulted. 



Dr. B. J. Jeffries alluded to experiments which had been made 

 by Dr. Mitchell at Philadelphia, and exhibited the results of 

 similar ones of his own, in injecting strong solutions of sugar un- 

 der the skin of frogs ; if the animals be kept from water they die 

 in a few hours, but if kept in water they recover, with, however, 

 the production of a cataract in both eyes ; the cataract being con- 

 lined to the superficial posterior layers, the interior of the lens 

 remaining clear. 



Dr. Williams remarked that the cataract thus produced disap- 

 pears in course of time ; this is an interesting fact, as this con- 

 dition in man never disappears unless the capsule of the lens be 

 ruptured either spontaneously or by art. He had noticed cataract 

 in persons affected with diabetes. 



Mr. Stodder exhibited the tooth of a large sperm 

 whale, with an abnormal nodular growth of cementum in 

 the interior and about the base of the tooth. 



Dr. C. T. Jackson presented, in the name of Jules Mar- 

 cou, a pamphlet on the " Dyas and Trias," in which that 

 author states that the Roxbury conglomerate belongs to 

 the period of the new red sandstone, — an opinion from 

 which Dr. Jackson entirely dissented, maintaining that 

 it underlies the coal. 



Mr. Bouve remarked that he had been able to trace 

 the gradual change from the conglomerate into a com- 

 pact, homogeneous, almost jaspery rock, the latter being 

 very striking in Hingham. 



