A STUDY IN MORPHOLOGY. U5 



In the adult (fig. t>4) the seaphognathite is absent ; the endopodite is rudimentary 

 and the second joint of the base (2) is very much wider than the first (l), and has 

 fifteen cutting hairs arranged in three rows, while the first joint has only four very 

 much longer serrated cutting hairs. The basal joint has only one plumose hair as 

 before, but the second joint has one on each side of the blade. 



The second maxilla. 



The second maxilla is present as a bud (fig. 24, MX. 2) in the egg, and it becomes 

 functional in the first Protozoea, and persists without very much change to maturity. 



In the first Protozoea (fig. 31) it has a long, many -jointed basal portion (h), with slender 

 simple hairs on its inner edge ; a two-jointed endopodite (en) with three simple hairs 

 on its tip, and two on the second joint ; and a small seaphognathite with plumose 

 hairs. 



In the last Zoea (fig. 47) the hairs on the inner edge are plumose, and one of 

 the three hairs on the small seaphognathite is much longer than the others. 



In the Schizopod stage (fig. 53) the limb is thick and long, the seaphognathite is 

 rudimentary, and the endopodite is small, and has no terminal hairs. 



In the adult (fig. 67) the endopodite and all but three of the joints of the basal 

 portion are absent. The first of these (3) is the largest and has a broad edge, with a 

 number of cutting hairs, while the others (2 and 1) are narrow and have three hairs 

 each. All these hairs are simple. The seaphognathite is elongated, and is now about 

 as long as the body of the appendage, to which it is joined by a narrow neck. The 

 inner end has four plumose hairs, three of which are about as long as the appendage, 

 while the fourth was short and apparently broken in all the specimens which I 

 examined. The outer half of the seaphognathite has three short straight plumose 

 hairs on its outer end, and five somewhat longer ones on its inner side. 



Thejirst maxilliped. 



The first maxilliped is represented by a bud in the. egg Nauplius (fig. 21 J\Jj>. 1) and 

 it becomes functional in the first Protozoea., and then consists (fig. 32) of an unjointed 

 exopodite (ex) with four long terminal hairs ; a four-jointed endopodite (en), with three 

 long terminal simple hairs, and a shorter hair springing from the inner edge of each 

 joint ; and an obscurely two-jointed basal portion with short simple hairs on its inner 

 edge. 



In the Zoea stage (fig. 48) the hairs on the inner edge and on the exopodite are 

 plumose, and the endopodite is long and six-jointed. 



In the Schizopod stage (fig. 50, Mp. 1) the joints are obscure ; the exopodite 

 is nearly as long as the endopodite ; all the hairs are plumose, and about equal in 

 length, and there is a double row along the inner edge of the appendage. 



