REPORT OF COMMISSIONERS OF INLAND FISHERIES. 47 



in some degree, to the intense muscular activity of the ambulatory 

 exopodites and to the expansion in the region of the gills as these 

 become functional to a larger degree. 



In this first stage the first pair of antennae project hardly to the 

 end of the rostrum. The endopodites which go to form the smaller 

 and inner members of the first antennae have just commenced to 

 bud off on the inner side of the outer member, the exopodite, and are 

 each furnished with one long seta. The exopodite has at its end a 

 tuft of four or five smaller setae. The second antennae at this stage 

 are composed of two portions: a broad, leaf -like outer portion, the 

 exopodite whose inner margin is curved and supplied with a variable 

 number of feathered setae, and whose tip holds one sharp spine; 

 secondly, a more slender inner part, the endopodite, bearing setae 

 at both sides and tip, but whose divisions into antenna segments are 

 not yet visible. (Plates VII, XIII.) 



Of the other appendages of the cephalo-thorax, the maxillepeds, 

 the ambulacral appendages, and chelipeds occupy a position much 

 posterior to their relative position in the adult. The second maxille- 

 peds of the first larval stage occupy relatively the position of the 

 chelipeds of the adult, while the chelipeds of the first have their 

 body origin about midway along the ventral border of the carapace. 

 All the walking legs have a correspondingly posterior position relative 

 to that of the adult type. (Plate XVI.) 



Of these appendages, the maxillepeds, chelipeds, and ambulatory 

 are all supplied with paddle-like attachments, the exopodites. (Plate 

 XIII). These are furnished with marginal hairs and undergo a rapid 

 vibratory motion downward and somewhat backward. The muscular 

 portion of the basal segments of these exopodites is highly developed, 

 while in the legs themselves, which are not yet functional for crawling, 

 the muscular development is very slight. 



The abdomen of the first stage lobster bears no appendages, 

 although the swimmerets, which are to appear in the second stage, 

 can be observed beneath the cuticle in every segment of the abdomen, 

 but the first and last. The last abdominal segment, which now con- 



