HOMOLOGIES OF CRUSTACEA. 25 



second antennae is connected; and the sutures about the base of the 

 second or outer antennae often show this conspicuously.* In many of 

 the Maiadae, the immoveable basal joint of these organs is continuous 

 with this episternal piece, and in other species, the relation is still 

 more evident in the manner explained above. In the Thalamita spi- 

 nimana (from the Feejees), the sutures of the episternal piece may be 

 distinctly traced across the epistome, so that the base of the antennae 

 is thus cut off from the rest of the epistome, and the direct relation of 

 the antennary base and the episternal piece is obvious on inspection. 



This position of the second antennae is in accordance with the 

 established principle that the articulated members pertain to the epi- 

 sternal pieces or plates. This therefore confirms still further our con- 

 clusion, that the anterior portion of the praelabial area belongs normally 

 to the second antennary segment. 



The inward direction of the sutures in the praelabial surface (or 

 palate) seems to show that the whole of this surface does not pertain to 

 a single segment. The outer suture actually separates an outer portion, 

 which is not included in either the sternal or episternal pieces; and 

 also, the rather abrupt termination of the medial suture before reaching 

 the margin behind (and in some cases divergent lines passing from its 

 extremity parallel nearly with the posterior margin of the plate), tends 

 to convince us that the posterior part of this praelabial plate* is man- 

 dibular, while the anterior is second antennary. The mandibular 

 portion of this plate, if these views are correct, will be the posterior 

 margin and the part outside of the outer episternal suture (2> 2 ). In 

 the Lupa tranquebarica, these sutures are distinct, and this outer por- 

 tion alluded to, evidently has different relations from the inner. 



The inferior surface of the carapax is marked in the Brachyura 

 with a suture (r, r 1 ), extending from the anterior angle of the buccal 

 area to the posterior margin of the body, just over the base of the 

 posterior legs. This suture is the "epimeral" suture of Milne 

 Edwards, who considers the ventral piece cut off by it, the epimeral 



* The same is seen in fig. 9 c, plate 16, of a Lupa from the Sandwich Islands. Here 

 the epistome is obsolete, excepting its medial portion ; the letters have the same signifi- 

 cation as above; a 1 is the base of inner antennae; a 8 , outer antennae; e, epistome; p, 

 medial fissur# in praelabial plate ; p a , outer suture of praelabial plate (the suture or emar- 

 gination intermediate between these two is not apparent in this species). The praelabial 

 surface is crossed by a ridge separating the efferent canal from the rest of the surface. 

 The connexion of the base of the outer antennae with the anterior margin of the praela- 

 bial plate is well seen in this figure. 



7 



