cxlvii 



October 19, 1874. 

 Dr. Geo. Engelmann, Vice President, in the chair. 



Publications received, laid upon the table. 



The Corresponding Secretary presented a gold medal received 

 from the Royal Frederick University of Norway, and struck in 

 commemoration of the 1, oooth anniversary of the first kingdom. 



Dr. L. A. Richardson spoke of several mounds which he opened 

 last July and August in the vicinity of King's Lake, on the Mis- 

 sissippi, a few miles above the Missouri. They were burial 

 mounds, and the graves were all laid north and south, and were 

 covered with stone slabs. They were on the high crests of the 

 bluff. 



Dr. Engelmann referred to observations by Dr. Wislizenus of a 

 similar nature in similar situations, some distance down the river. 

 The graves were rather close together, not covered with a mound, 

 and the remains surrounded by slabs of limestone. 



Mr. Riley gave some new biological facts regarding the Grape 

 Phylloxera, showing how the studies of the present year had well 

 given us its complete natural history. 



He had obtained the sexual individuals of three distinct species, namely, 

 of Ph. vastatrix Planchon, Ph. Rileyi Lichtn., and a large species beaten 

 from ^hiercus obtusiloba and which was apparently Ph.caryivcaulis. Fitch, 

 which makes galls on Hickory. The life-history of Ph. vastatrix may be 

 thus epitomized : It hibernates, mostly as a young larva, torpidly attached 

 to the roots. With the renewal of vine-growth in the spring, this larva molts 

 and rapidly increases in size and commences laying eggs. These eggs hatch 

 and produce, in due time, apterous, egg-laying, parthenogenetic mothers 

 like the first one. Five or six generations of these virgin mothers follow 

 each other, when, about the middle of July, some of the individuals begin 

 to assume wings. These are all females, and, like the wingless mothers, 

 bring forth parthenogenetic eggs. They rise in the air and spread to new 

 vineyards, where they lay their eggs— usually 2 or 3 in number and not 

 exceeding 8— and then perish. These eggs are of two sizes, and in the 

 course of a fortnight the larger ones give birth to females, the smaller to 

 males, which are born for no other purpose than the reproduction of thei r 

 kind, and are without means of flight or of taking food or excreting. The 

 sexes pair and the female is delivered of one large egg, which doubtless 

 gives birth to the ordinary larva, which crawls on to the roots and re- 

 commences the virginal underground multiplication. He had some reason 

 to believe that there were two of these developmental cycles each j'ear, 

 i.e., that the winged and sexual forms were twice produced annually; yet 



