376 MEMOIRS OF THE NATIONAL ACADEMY OF "SCIENCES. 



exposed ;it low tide. Alpheus minus has a similar environment and is similarly colored. Alpheus 

 hetcrochelis from Nassau, New Providence, on the other hand, lives under loose stones, ainid the 

 white coral sands of the beach, and is noticeably transparent, looking as if the color had been 

 bleached out of it. The body is sprinkled with dots of brown pigment. The claws and legs are 

 pale greenish. Young and old are invariably colored alike. 



In a collection of adult Alpheus of either sex of the same or of several species, where there is 

 a difference iu size of the large claws, it is noticed that either the right or the left, indifferently, 

 may be the greater. As we will see, this differentiation of the chela* begins in one instance before 

 the animal is hutched. Is this right and left handed condition to be explained by inheritance 

 from the parents ? In about forty lame of a small brood of Alpliens saitlcyi, all invariably had the 

 left claw enlarged, and in a smaller number (all that were preserved), from another female of the 

 same species, the left chela was also in each case the larger. This would indicate that the young 

 of the, same mother have always the same claw, either right or left, the greater, and that this phe- 

 nomenon is one of direct heredity from the parents. But to prove this it is only necessary to trace 

 right and left handed broods to parents which are themselves right and left handed, respectively. 

 This, unfortunately, I have not done, as my attention was not called to the subject while at the 

 seashore.* 



The breeding season of Alpheus begins at Beaufort, N. C., about April I. It covered the 

 period of our stay at Nassau (March to July), and probably began earlier and lasted considerably 

 later. t There the temperature is high and remarkably constant, the annual range being about 15 

 (temperature of air 70 F. in March, 80 in June), and in consequence the early phases of devel- 

 opment are rapidly passed. Not one prawn in a hundred was found with eggs iu an earlier stage 

 than that of yolk segmentation. 



II. VARIATIONS IN ALPHETJS HETEROCHELIS. 



A renewed comparison of Alphcux hcterix-lirlix with the Nassau form lends support to the con- 

 clusion already reached that we here have to do with two varieties of the same species. There are 

 certain differences, which systematic zoologists might regard as of specific value, but they are 110 

 greater than we have proved to exist among individuals of the same species living in the same 

 sponge, (v. Section V.) 



The Nassau specimens average smaller, but the chief difference lies iu the shape of the small 

 chela. The propodus of this appendage in the Nassau form is relatively shorter and thicker in 

 both sexes. Both lingers are nearly cylindrical, and covered with hairs, which are distributed 

 either singly or in tufts. In the Beaufort hc.tcroi-he.Ux there is a striking variation in the small 

 chela which appears to have escaped detection. Judging from the small collection at my command 

 it is a sexual variation. In the females the small chela is like that of the Nassau form, but is 

 usually longer and slenderer. The dactyle is about one-half the length of the propodus. In 

 the males the dactyle is relatively much shorter, and has a median longitudinal carina which is 

 continued into the apex of the claw. In transverse section the dactyle is trihedral, with two con- 

 cave sides, corresponding to the deep groove on either side of the keel. These grooves are fringed 

 with a row of stout plumose setre. Similar rows of seta; occur on the sides of the opposing 

 " thumb. 1 ' 



Perhaps the most interesting variation which I have observed iu the Beaufort IttlcrocIteUs has 

 reference to the size of the egg. The eggs in this locality have an average diameter ot about one 



" Mr. .1. .1. Northrop, of Columbia College, while at Nassau in the winter and .spring of 1S90, kindly offered to 

 collect for mo some specimens of Alplieus sauJcyi with, young. Ou February 10 he rollivieil six females, five from green 

 sponges, one of which had a brood of sixteen young, and one small female with three lnrv:r from the "loggerhead"' 

 sponge. In the first instance the left chela was the largest in the mother and in rnrli <>f Hi/ 1 sixteen young. In the 

 latter, two had the right claw enlarged and one the left. The inference is suggested that when the claw of the same 

 side is invariably the greater in all the young, this character is doubly inherited from both father and mother, but the 

 data are insufficient to settle this point. 



t Professor H. V. Wilson found this species breeding around Rreen Turtle Key from July until December. Mr. 

 Northrop fouud newly hatched young early in February. It therefore breeds the year through, which is probably 

 true of many of the Crustacea. 



