112 PROCEEDINGS OP THE ACADEMY OF 



The three sulci are of a dark-brown tint. Besides these, there are on each side 

 of the cephalathorax four dark, but more or less obsolete grooves. At the posi- 

 tion of the lateral eyes on each side there exists a dark-brown spot, and between 

 them and the anterior transverse groove is a pair of similarly colored round de- 

 pressions. The maxillary palpi are of a more decided orange than the body. The 

 second joint has its anterior face armed with eight or ten very small spines or 

 spinous tubercles, and one or two larger ones. The spines on the lower margin of 

 the third joint are longer than those on the upper. On each, the two nearest the 

 body are much larger and more closely approximated than the others. Between 

 the margins are a few very small spinules. The spinous tubercles on the upper 

 portion of the posterior surface are more numerous than those on the lower. 

 The fourth joint is dilated superiorly in its distal portion : where on the upper 

 margin are placed three very long acute spines, with two or three much 

 smaller ones. The lower margin has five spines, three of them being much 

 smaller than the other two. The moveable finger is very long and acute. The 

 upper surface of the abdomen has along the mesial line a double row of dark- 

 brown spots, and on either side a series of blotches of the same color, one on 

 each scutum. The legs and sides of the abdomen are very rough. The under 

 surface of the abdomen is smooth. 



Huh. Lower California. Smithsonian Museum. J. Xantus de Vesv. 



May bth. 



The President, Mr. Lea, in the Chair. 



Twenty members present. 



The following paper was presented for publication : 



On the Lestris Richardsoni, etc. By Elliott Coues, M. D. 



May 12th. 

 The President, Mr. Lea, in the Chair. 



Sixteen members present. 



The following papers were presented for publication : 



Synopsis of the Marine Invertebrata collected by the late Arctic 

 Expedition under Dr. 1. 1. Hayes. By Win. Stimpson. 



Descriptions of the soft parts and embryonic forms of one hundred 

 and forty-three species of Unionidse of the United States. By 

 Isaac Lea. 



New Exotic Unionidae. By Isaac Lea. 



May 19 th. 

 Mr. Vaux, Vice-President, in the Chair. 



Twenty members present. 



The Secretary announced the death on the 3d inst., of Col. 

 Mark W. Ccllet, M. D., aged 36, late a member of the Academy. 



The following papers were presented for publication : 



Contributions towards a Monography of the Pholadacea, etc., No. 2 

 By Geo. W. Tryon, Jr. 



[May, 



