STATE GEOLOGIST. 115 



SUB-FAMILY CHIROCEPHALINJS. 



Characters — Body slender, abdomen long and many jointed, antennse of the 

 second pair in the female very short and broad, while those of 

 the male are prehensible. 



GENUS Chirocephalus. (Sig. hand-headed.) 



Bibliography. — Chirocephalus, Prevost, Jour, de Rhys., Ivii., 37, 1803. 



Thompson. 



Branchipus, M. Edwards. 



Fischer. 



Latreille. 



Desmarest. 



Guerin. 



Lamarck, etc. 



Ino, Schrank, 1803. 



Oken. 



Cancer, Shaw. 



Some member of this sub-family was found, during the autumn months, in a 

 pool by the road-side but no accurate drawings were made and attempts to 

 re- discover it have failed, so it remains uncertain what species it was. A figure 

 is given of Chirocephalus diaphanus and the following discnption, mostly from 

 Dr. Baird's work, will serve both for a better understanding of the genus and 

 for comparison, when other specimens are obtained. 



The head consists of two segments, the posterior of which is more slender 

 than the anterior, and is usually called the "neck." 



The antennae are very important in. the whole group, as furnishing basis for 

 classification. The superior anteanse are alike in male and female, and are 

 filiform, straight, many -jointed, and veiy flexible. At the extremity are a number 

 of small setse. The joints of these antennae are with difficulty seen. The length 

 equals the head. The inferior pair of antennae are curious organs, from which 

 the genus derives its name, and have been mistaken for madibles and various 

 other entirely different organs. 



They are essentially prehensile organs, and consist chiefly of two large appen- 

 dages, which occupy the forepart of the head, and are curved downward toward 

 the thorax. They are articulated about the middle of their length; the first joint 

 being large and fleshy and having a short, movable, conical appendage on its 

 external edge; the second being curved, cylindrical, somewhat flattened at its 

 extremity, and bearing a strongly toothed process at the base. 



Arising from the base of the fiset joint of each of these appendages is another 

 set of organs, called by Shaw "the trunk.'' These each consist of a long, flat, 

 curved, very flexible body, composed of many short joints the edges of which are 

 acute, giving a toothed sppearance to this organ. From the outer edges of these 

 arise fbur long and flexible appendages, which are toothed near the end, and 

 also a triangular plate which is folded like a fan when not in use. {This is 

 removed in fiigure b of plate 1, but shown at d.) These organs are generally 

 carried rolled under the head, somewhat in the manner of the proboscis of a 

 butterfly, being only visible externally as a protuberance. 



These prehensile organs are used in retaining the female during copulation. 

 In the female they are much more simple, being: simply two flexible, horn-like 

 bodies, carrying none of the appendages which pertain to the male. 



