THE AMERICAN LOBSTER. 183 



to the primary egg-membrane that any attempt at its removal almost inevitably results 

 in stripping oil' the blastoderm with it. It is, however, soon absorbed, or at least 

 detached, so that in the early egg-nauplius stages the shelling of the egg is quite an 

 easy matter, yet when the egg-nauplius is fully developed the inner layer of the 

 capsule invariably sticks to the tips of the antennae, which are usually torn off with 

 its complete removal. 



At a stage closely following the egg-nauplius the embryo is inclosed by three dis- 

 tinct membranes. I think it probable that the delicate inner cuticle, which can now 

 be removed by the aid of hot water without injury to the parts, is a distinct structure 

 from the blastodermic membrane just mentioned. The appendages at this time are 

 gloved with a cuticular molt, evidently distinct from that which comes off with the egg- 

 capsule when the animal is hatched. When eye pigment is formed these envelopes 

 are very easily demonstrated, as seen in cut 20, plate F, where they have been distended 

 by the prolonged action of picro-sulphuric acid. Up to this time it is therefore probable 

 that at least three embryonic molts have occurred. Others follow during the long embry- 

 onic life, and, as I have already shown, when the animal is about to hatch it is inclosed 

 in a cuticular molt which must be shed before it can enter upon its larval career. 



In the second molt, preceding the second larval stage, the delicate shell is cast 

 entire, the only break being, as in the later stages, along the margins of the inner fold 

 of the carapace — that is, in the epimeral region of the branchial cavities and next 

 the abdomen. The shed cuticula is transparent, colorless, and flexible, and contaius 

 little or no lime. The abdomen is usually withdrawn last, as is the case in adult life. 



The cast shell at the fourth molt, which precedes the fourth stage, contains a 

 little lime, but no pigment. The fifth ecdysis, which ushers in the fifth stage, is 

 more noteworthy. A larva of this period molted in a glass dish on my table in the 

 forenoon of July 13, 1892, and was soon attacked by others in the dish and killed. The 

 carapace is gradually elevated from behind, and the animal escapes through the open- 

 ing thus formed. The calcareous shell, which is of a beautiful light-blue color, retains 

 its shape perfectly. The carapace, as early as the fourth stage, has a characteristic 

 areolation (see figs. 113 and 115, plate 35) and is covered with short setae. There is a 

 wide median stripe or band of absorption which branches into the cervical groove on 

 either side and widens at the rostrum. The carapace can be easily split along this 

 thin unpigmented area. 



The ecdysis of a lobster in the sixth stage, the color of which has already been 

 described (No. 34, table 34), was observed under similar circumstauces. On the 8th of 

 August this lobster molted again while I was watching it. At about 9.30 a. in., when 

 first examined, the abdomen was drawn away from the thorax, showing a distended 

 pink membrane which connects these parts of the shell. Fifteen minutes later the 

 carapace was elevated, the pressure of the inclosed body swelling out the mem- 

 branes slowly. At 10.24 a. m. the young lobster turned over on its side and in three 

 minutes was out of its shell, about an hour having elapsed from the moment when 

 the process, already begun, was observed. The eyes and cephalo- thoracic appendages 

 are withdrawn first, and when these are free the animal slips away from the old shell, 

 the abdomen coming out last, as in the adult lobster. 



The color of the cast shell is blue, with some green and brown pigment ou the 

 tergal surfaces. Pigment is now gradually deposited in the outer calcified layer of the 



