-r y 35-3 



S. I. Smith — Early Stages of the American Lobster. 259 



endognathus are all nearly cylindrical, and the five distal are armed 

 with slender spines along the inner sides. The meral and propodal 

 segments are equal in length, the ischial and carpal also equal in 

 length, but a little shorter than the meral and propodal, while the 

 terminal segment is scarcely longer than the diameter of the propo- 

 dus, tapers rapidly to the tip, which is armed with three slender spines, 

 the shortest of which is considerably longer than the segment itself 

 and the longest nearly three times as long. The spines upon the 

 distal end of the propodus are about as long as the segment itself, 

 while those iipon the inner sides of the other segments are mucli 

 shorter. IVIost of the spines are armed for a large part of the length 

 with two rows of acute and closely set teeth ; although the two long- 

 est of the terminal ones and some of the others appear to be wholly 

 unarmed. The exognathus (fig. 13, a) is about half as long as the 

 endognathus, the distal, flagelliform portion l)eing longer than the 

 basal and composed of eight or nine segments, each of which is fur- 

 nished at the distal end with two very long jointed and ciliated hairs, 

 the distal ones fully as long as the flagelliform portion, but the ones 

 toward the base somewhat shorter. The epignathus (fig. 13, h) and 

 the three branchial appendages (fig. 13, c) are very rudimentary, 

 being represented by small sack-like lobes, the one representing the 

 epignathus larger than the others and distinguished from them by its 

 better defined outline and less cellular structure.* 



The anterior cephalothoracic legs (plate XIV, fig. D, enlarged 20, 

 and plate XVII, fig. 9, enlarged 40 diameters), corresponding to the 

 great chelate legs of the adult, are exactly alike, scarcely longer than 

 the external maxillipeds, and only imperfectly subcheliform, with no 

 power of prehension; The endopodus is stouter than in the second 

 and third legs, but scarcely, if any, longer. The segments are all 

 nearly cylindrical, and all except the coxal are armed along the inner 



* The number of brancldas, or branchial pyramids, in the American lobster is 

 twenty on each side : a single small one upon the second maxilliped, three well- 

 developed ones upon the external maxilliped, three upon the first cephalothoracic leg, 

 four each upon the second, third, and fourth, and one upon the fifth. The number is 

 probably the same in the European species, although the statements of different 

 authors in regard to it are confused and contradictory. De Haan (Fauna Japonica, 

 Crustacea, p. 146) states the number, for the genus Homarus, as nineteen on each 

 side, giving only two for the external maxilliped, while Owen (Lectures on the Anat- 

 omy of the Invertebrate Animals, 2d ed., p. 3'22) and Edwards (Histoire naturelle 

 des Crustaces, tome i, p. 86) gives the whole number on each side as twenty-two, 

 although Edwards in anotlier place in the same work, under Homarus (tome iii, p. 

 333), gives twenty as the number. 



