256 THE CRUSTACEA 



carapace have been studied by Boas and by Bouvier. Only a few 

 points can be mentioned here. In the lobsters and crayfish a con- 

 spicuous groove (Fig. 145, c) crosses the dorsal surface of the 



carapace transversely about 

 the middle of its length 

 and curves forwards on 

 either side. This groove, 

 named the " cervical groove " 

 by Milne - Edwards (c in 

 Boas's terminology, the 

 " branchial groove " of Bou- 



Carapace of the Norway* Lobster (Nephrops nor- viei> )> WaS Supposed b y him 



vegiciis) from the side. (After Boas.) The letters refer- to indicate the lillC of 



ring to the grooves of the carapace are those used by j ... 



Boas. e,e', the "cervical groove "of Bouvier, "anterior division between tne por- 



cervical groove " of Borradaile ; c, " branchial groove " *i nnQ n f flip r>a r anapp ari<5 



of Bouvier, " posterior cervical groove " of Borradaile. tl0ns ( 



ing from the antennal and 



mandibular somites respectively. Other writers, for instance, 

 Huxley, regarded it as marking the limits of the cephalic and 

 thoracic regions. There appears to be no ground, however, for 

 regarding this groove as of greater importance than some of the; 

 other grooves of the carapace. In some cases an equally con- 

 spicuous transverse groove (e of Boas, " cervical groove " of Bouvier} 

 (Fig. 145, e, e) crosses the 

 carapace a little in front of the 

 cervical, and as this is the only 

 transverse groove, apparently, 

 to be found in any of the lower 

 Macrura (Stenopidea, Caridea), 

 it seems at least as likely to 

 afford an important morpho- 

 logical landmark. In SOme Carapace of CalUanassa nomebritanniae (Tha- 

 pfl<ap<3 nnrrinns; of tVip parnnapp lassinidea) from the left side. (After Borradaile.) 

 Cases portions OI tne Carapace c> e , the grooves so lettered by Boas (see Fig. 144) ; 

 mav be Separated bv a longri- lM,lineaanomurica (perhaps also the lineadramii- 

 ,. , i -r. i tlica\ the front part of which is the line b of 



tudinal groove Or Uncalcified Boas; It, Unm thalassinica (perhaps also the 

 V U v f tinea homolica). the front part of which is the line 



line, which may even form a <j O f Boas ; r, rostrum. 



movable hinge. Of this nature 



are the linea thalassinica (Fig. 146, Lt) of the Thalassimdea, with 



which the /. homolica of the Homolidae may perhaps be identical, 



and the 1. anomurica (La) of many Anomura, identified with the 



/. dromiidica of Dromiidae and the unfortunately named " epimeral 



suture" of other Brachyura. 



The sternal surface of the cephalothorax is very narrow in 

 many Macrura, but is often broad in those which have a depressed 

 form. It is broad in many Anomura and in all Brachyura, with 

 the exception of Kaninidae. The thoracic sterna are usually clearly 

 distinguishable, and, in the lower forms, seem to preserve a certain 



