THE HISTORY OF THE LOBSTER. 417 
cephalothoracic legs having no exopodal branches and the abdom- 
inal legs being already developed. Of the early stages of the 
numerous other genera of Astacidea and Thalassinidea, scarcely 
anything is known, but as far as is known, none of them appear 
to approach the larvie of the lobster. Most of the ‘species of 
Crangonidz and Palemonidz (among the most typical of macrou- 
rans), of which the development is known, are hatched from the 
egg in the zoéa stage, in which the five posterior pairs of cephalo- 
thoracic appendages, or decapodal legs, are wholly wanting, as are 
also the abdominal legs, while the two anterior pairs of maxilli- 
peds, or all of them, are developed into locomotive organs. In no 
period of their development do they have all the decapodal legs 
furnished with natatory exopodal branches. There are undoubtedly 
larval forms closely allied to those of Homarus in some of the 
groups of Macrourans, although they appear to be as yet unknown. 
‘* Notwithstanding these larval forms of the lobster seem to have 
no close affinities with the known larve of other genera of macrou- 
rans, they do show in many characters a very remarkable and in- 
teresting approach to the adult Schizopoda, particularly to the 
Mysidæ. This appears to me to furnish additional evidence that 
the Schizopods are only degraded macrourans much more closely 
allied to the Sergestide than to the Squilloidea.” 
The mode of moulting of the lobster, does not seem to have 
been observed. We are indebted to Mr. William H. Silsbee for in- 
formation and specimens regarding that of the adult lobster. He 
thinks it only moults once a year after having nearly attained its 
maturity at some period between May and November. n 
vember 8th he saw one moult. It drew its body out of a rent in 
the carapace, or shell covering the front division of the body. 
The carapace splits from its hind edge as far as the base of the 
rostrum, or beak, where it is too solid to separate. The body is 
drawn out of the anterior part of the carapace. It has been a 
question how the creature could draw its big claw out through the 
small basal joints. The claw, soft and fleshy and very watery, is 
drawn out through the basal joint, without any split in the old 
crust. In moulting, the stomach, with the cartilaginous masses 
and bands and œsophagus, is cast off with the old integument. 
The length of the animal observed before moulting was six and a 
half inches ; immediately after seven and a any a sudden in- ` 
crease in length of three-quarters of an inch.—A. 
AMER. NATURALIST, VOL. VIII. 27 
