504 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



Plate XXI. 



Fig. 1. First larva of Alpheus saulcyi, var. breiHcarpus, from "loggerhead" sponge. Hatched at 



4 p. m., June 10, 1887. A small amount of unabsorbed food yolk remains in the 



stomach. x26. 

 Fig. la. Line to indicate length of larva. L.=3.5°"". 

 Fig. 2. Second larva of same, from brood hatched on evening of June 8. Food jolk nearly 



absorbed. About tweuty-four hours old. x26. 

 Fig. 2a. Line to show length of larva. L.=4""". 

 Fig. 3. Head of young from same brood. Four days old. x52. 

 Fig. 4. Right first pereioi)od of larva of A. saulcyi, var. brevicarpus, before the molt preparatory 



to stage shown in Pig. 1. Seen from inner side. x52. Swimming hairs of exopodites 



rudimentary. 

 Fig. 5. Egg embryo of A. saulcyi, var. longicarjyus, nearly ready to hatch. The large chela of the 



left first pereiopod is conspicuous below the autenni*. x46. 

 Fig. 5a. To show natural size of the same. Slightly too large. Dimensions: xooXySoiuch. 

 Fig. 6. First and second maxilla of first larva (Fig. 1) before preparatory molt. The parts are 



glov^ed with the embryonic skin, which is usually cast off at the time of hatching. 



X227. 

 Fig. 7. Left first pereiopod of same, seen from inner side. x52. 

 Fig. 8. Third larva of Alpheus saulcyi, var. brevicarpus. From same brood as second larva. Fig. 



2. Not over twenty-eight hours old. Food yolk not wholly absorbed. x26. 

 Fig. 9. Telson and rudimentary uropods, seen from below, x 52. 



