MACROURI. 211 



meut of the size was sensible. I found the specimen dead on the last 

 day of the month, without any obvious cause, though for some time the 

 colour had faded. Here the intervals of exuviation were .short, none of 

 them exceeding forty days. When of such transparence as exhibited in 

 these examples, the integument of all specimens must be of incalculable 

 tenuity. 



Without any positive evidence of the fact, various circumstances 

 have induced me to conjecture that this sj)ecies may be migratory. 



Plate LV. 



Fig. 1. Galathea spinigera. Bastard Thorny Lobster; vernacularly the 

 Tommy Harper. 



2. Extremity of the extended tail. 



3. Young specimen. 



4. Young specimen. 



5. Young specimen, a female, which survived five or six weeks, — 



Galathea rugosa ? 



6. Young specimen. — Galathea rugosa ? 



7. Young specimen, very hairy. 



8. Spawn, enlarged. 



B.— DECAPODES, TEN-LIMBED, LONG-TAILED, CRU.STACEANS— ilWCiJOt//?/. 

 ASTACUS, THE LOBSTER. 



The two preceding animals will suitably illustrate the transition of 

 the form of the Crab to some other than previously discussed in the pre- 

 ceding pages. Its most immediate ally will be found in the Lobster. 

 The form of this genus differs considerably, as is well known, from that 

 of the Crab, and its properties prevent it from being confounded with the 

 creatures belonging to other tribes. 



§ 1. AsTACUS NoRVEGicus,i/?H«G?«s, Norwegian Lobster. — Nephrops, Leach. 

 Plates LVI., LVIL, LXX. figs. 6, 7, 8. 



From the Cancer we endeavour to advance by intermediate stages, 

 wherein are found great modifications, to the Astacus. Perhaps, instead 



