472 ANNUAL KEPORT SMITHSONIAN INSTITUTION, 19 31 



The first maxillae (fig. 18, D, E) have a structure similar to that 

 of the second maxillae, but they differ from the latter in a number 

 of details. The body of the a'ppendage is divided by a distinct line 

 of articulation between the cardo {Cd) and the stipes {St)^ and is 

 provided with strong sternal adductor muscles {KL) inserted on 

 both the cardo and the stipes. The dorsal musculature consists of 

 two groups of promotor fibers (/) and a group of remotor fibers {J). 

 The promotors are inserted on the base of the cardo and on the 

 distal end of the stipes ; the remotors are inserted on the basal angle 

 of the lacinia (E, Lc) . The endite lobes of the first maxilla are well 

 developed. The lacinia {Lc) is an independent plate attached by 

 membrane to the stipes; but the galea {Go) is a direct continuation 

 of the distal part of the stipes. The telopodite (Tlpd) is reduced 

 to a peglike rudiment arising from the stipes at the base of the 

 galeal lobe. As we shall see, there are many points of resemblance 

 between the first maxilla of Anaspides and the maxilla of an insect. 



Lying immediately before the first maxillae and behind the man- 

 dibles is a pair of large, flat, transverse lobes, the paragnatha (fig. 

 18 B, Pgn). The paragnatha hang downward from the anterior 

 end of the median sternal plate of the first maxillary segment, which 

 has a median channel ending at the base of the narrow cleft between 

 the bases of the paragnathal lobes. The possible homology of the 

 crustacean paragnatha with the insect superlinguae has already been 

 discussed (p. 455), and we have observed that the paragnatha in 

 some Crustacea are intimately associated with a median sternal 

 lobe (fig. 7 C), the three forming a composite organ much resembling 

 the insect hypopharynx, and having the same situation between the 

 mandibles and the first maxillae. 



The mandibles of Anaspides are strong jaws (fig. 18 A) suspended 

 from the mandibular segment, to which each is articulated by a 

 single dorsal point of articulation {a') with the inner surface of the 

 overlapping lateral lobe of the tergum. Ventrally the free end of 

 each jaw is produced into a large lobe {Bnd), subdivided into a 

 distal, toothed incisor part, and a heavier, proximal molar part. 

 Laterad of the base of the terminal lobe arises a three-segmented 

 telopodite, or palpus {Tlpd). It is clear that each mandible of 

 Anaspides consists of the limb basis of an appendage {LB), bearing 

 a large, immovable endite lobe {Bnd), and of a small, segmented 

 telopodite {Tlpd). The mandibular basis shows no subdivisions 

 corresponding with the cardo and stipes of a maxilla. 



The musculature of the Anaspides mandibles is characteristic of 

 the musculature of all arthropod mandibles that are movable on 

 single points of articulation. Each jaw is provided with two dorsal 

 muscles (fig. 18 A) and strong ventral muscles. The dorsal muscles 



