ANATOMY OF STYLETS OF CAMBARUS AND ASTACUS. 85 



from Oregon in February, or in October, 1904, there were a few 

 that presented the remnants of spermatophores on the ventral 

 surface of the thorax. In the best marked case these were some 

 hundred empty tubes, 3 to 4 mm. long, and more than .25 mm. 

 thick, of red-brown color, stuck close to the shell of the female 

 for the most part, though some had one free end standing up 

 about a millimeter into the water. Most were laid down carefully 

 side by side in groups. Some few were twice the usual length. 

 A few were on the base of the second leg, on one side ; more 

 were at the base of the third leg and close to the opening of the 

 oviduct. Still more were at the bases of the fourth legs and 

 between them just anterior to the annular plate, onto which two 

 spermatophores extended. Two were on the sternum between 

 the fifth legs. The entire collection, in a sketch, forced one's 

 attention to the fact that they had either been originally placed 

 in depressions and angles where they would not be readily rubbed 

 off, or else that these seen were the survivors that had escaped 

 removal after more unprotected spermatophores had gone. Each 

 spermatophore had its tips greatly contracted, as if a soft material 

 had shrunk more at the end, somewhat like egg-cocoons of earth- 

 worms. 



Thus the male of the American crayfish Astacus must deposit 

 the sperm in tubes over the ventral side of the thorax of the 

 female, and not introduce it into any special cavity. 



In comparing the sperm-transfer apparatus here with that of 

 Carnbariis we find greater simplicity, as was to be expected for the 

 performance of this less specialized mode of transfer. 



The first stylet of this A. leniusculus (Fig. 14) is like that of 

 the English Astacus, as figured by Huxley (7) in the main, while 

 also being like the stylet of Cambarus. The base is simple and 

 without the specialization of form to nicely accommodate the 

 second stylet, but the ridge along the neck bears setae. The 

 spiral is obviously a hollow cone or tapering scroll with a very 

 wide orifice between the long external, and the shorter median 

 mass. The groove is much more open than in Cambarus and 

 the whole organ is less rigid and seems as if well made for a mere 

 conduit and not for an organ to be forced into a hard slit. The 

 stylet is not noticeably bifid and the rather blunt tip is the canula 



