146 



Part III. — Ticenty-first Annual Report 



lobe there is a short plumose seta, and on the inferior edge a short plain 

 hair. 



III. (Figs. 35 and 38). The condition is similar to the preceding. 

 The little plumose hair which is seen on the outer edge of the upper 

 lobe is shown in Fig. 12. 



Fig. 15 is an enlarged drawing of the palp. 



IV. (Figs. 13 and 36). In this stage one spine more was found 

 on the upper lobe, and one fewer on the lower lobe than in III., i.e. ten 

 on the upper and seven on the lower. 



In the specimen dissected the two first maxillae were not alike. The 

 palp of one side was normal (Fig. 13), while the palp of the first maxilla 

 of the other side had a single hair attached to the middle of the 

 second joint (Fig. 36), in this recalling the structure of the palp of 

 the first maxilla in the Megalops of Crangon vulgaris. 



Megalops (Fig. 47). The first maxilla in this stage retains a general 

 resemblance to the Zoea condition. It is 2 -jointed. From the basal 

 joint rises a narrow lobe. The second joint forms a large lobe, on the 

 outer side of which there is the palp. Except for an increase in the 

 number of spines on the two lobes their armature has not changed 

 much. 



The palp, however, is now a single- jointed flattened appendage, which 

 is bent on itself. 



In this specimen also the two first maxillae differed, viz. in the 

 number of spines on the lobes. 



1. (Fig. 42.) The palp is now 2-jointed. The first joint is broad and 

 peculiarly shaped ; it bears two smooth hairs at its middle. The second 

 joint is bent down away from the lobes, and carries two terminal 

 smooth hairs. 



The armature of the two lobes is shown in the sketch. 



Second Maxilla, 2m, Plates viii. and ix. 



The second maxilla consists of two joints, vide Fig. 55, which shows 

 the appendage in the IV. Zoea. The first joint (p'ot. ih.) has a long 

 lobe {I ') attached to it. This appears to be simply a process of the first 

 joint, not segmented off from it. The upper joint is cleft into two lobes 

 {I" , and l" ). To its outer edge is attached the scaphognathite which is 

 the homologue of the palp in the first maxilla. There is then in the 

 second maxilla a condition similar to that of the first- maxilla. Gurney 

 in his drawing of the second maxilla in the I. Zoea of Coiystes indicates 

 a condition resembling that described above. It is possible that the top 

 lobe {I") is the endopodite, but in none of the stages was it seen to be 

 segmented off. 



I. (Figs. 45 and 76). The endognath then consists of three lobes, of 

 which the two upper form the large lobe, and the third the small lower 

 lobe. Each lobe bears on its inner edge a number of bristles, which are 

 grouped on sub-divisions of the lobes. The spines on the upper double 

 lobe are long stiff hairs, some of which are provided with a few long lanceo- 

 late cilia, others are minutely serrated on their distal halves (Figs. 44 

 and 54). On the lowest lobe the spines are adorned with long 

 lanceolate cilia (Fig. 50). The spine formula is (5 + 3 : 4 + 5) : (4 

 + 3). Certain of these resemble spines that are found on the first 

 maxilla. 



On the upper and lower edges of the lobes there are groups of 

 delicate cilia. 



The scaphognathite is small and bears five long plumose setae. The 

 same number was found by Gurney in Corystes and by Mortensen in 

 Palcpmon Fahricii. In Orangon vulgaris also there are five set®. 



