STATE GEOLOGIST. 107 



LynceuSj Eurycercus and Alona. 



Ijynceus=Eurycercus of Dr. Baird. 



Eurycercus=Chydorus, Percantha and Pleuroxus. 



Alona==Alona, Acroperus and Camptocercus. 



In the genus Alona, he says, the beak diverges from the body at a large angle 

 (60" to 90°) with the shell adjoining, while in Eynceus it is usually curved par- 

 allel to it. 



But, as Dana himself admits, the distinctions are of doubtful importance, and 

 it would seem preferable to retain MuUer's old genus instituted for all of these 

 forms than to further complicate the matter until a large amount of material 

 shall be gathered and compared. The species observed will, therefore, be briefly 

 defcribed and the probable place in the rejected genera indicated. 



Lynoeus macrourus. Muller. 



Bibliography.— LjJiceus macrourus, Muller, Dan, Prod., 2397. 



Latreille *'H.ist. Nat. Crust., 207. 



M. Edwards, Hist. Nat. Crust., iii, i 



Monoculus macrourus, Genelin, Syst. Nat., 8008, No, 65. 



Monoculus macrourus, Manuel, Enc. Mith., vii, 733, No. 68. 



Fahricius, Ent. Syst,, ii, 499. 



Camptocercus macrourus, Baird, Ann. and Mag. Nat. Hist, ii; 

 Trans. Berw. Nat. Club, ii, 150; British Entomost. p. 128. 

 Description. — Carapace pear-shaped, transparent, finely lined longitudinally, 

 sinuated on the lower margin, which is ciliated for most of its length. Head 

 rather small, with a short, blunt beak projecting straight downwards. Superior 

 antennae rather large, situated about halfway from the extremity of the beak to 

 the body. Inferior antennae long, with long setae at the extremity, eyes small, first 

 pair of feet large, abdomen very long and slender, serrated with well marlaB(f 

 teeth on the posterior edge and terminating in the usual pair of claws. The 

 extreme length and narrovvness of the abomen formed the basis of the genus 

 camptocercus of Dr. Baird, this species being the only one described under it. 

 The intestine is convoluted, and there is an opening near the juncture of the last 

 segment of the abdomen with the rest of the body from which a long vessel 

 begins and extends above the stomach, as at (a) Fig. 1, Plate XV. This species 

 is quite abundant. 



Lynceus quadrangularis, Muller. 



Bibliography. — Lynceus quadrangularis. Mailer., Zool. Dan. Prod., No. 2393, 



1876. 



Latreille, Hist. Crust., 208. 



Baird, Trans. Berw, Club. 



M. Edivards, Hist. Crust., iii., 388. 



: ■ Kock, Deutsch. Crust. L. XXXVI. 



Monoculus quadrangulus, Gmetin, Maduel. 



Monoculus quadrangularis, Fdbricius. 



Monoculus striatus( ?) Jurine. 



Alona quadrangularis, Baird, Ann. and Mag. Nat. Hist., ii. 92 



Trans. Berw. Club, ii. 151; 



Entomostraca, p. 131. 



