NO. 6 ANNELIDA, ONYCHOPHORA, AND ARTHROPODA SNODGRASS 121 



Fig. 51. — Cephalic structures of malacostracan Crustacea in which the defin- 

 itive head is the protocephalon, as in Anostraca (fig. 50 A). 



A, Anaspides tasnianiae Thomson (Syncarida), protocephalon and appen- 

 dages, anterior view. B, same, mandibles and muscles, posterior view. C, 

 Spirontocaris polaris (Decapoda-Macrura), showing protocephalon (Prtc) 

 detached from carapace. D, Callincctcs sapidus Rathbun (Decapoda-Brachy- 

 ura) protocephalon and appendages, dorsal view. E, same, protocephalon, 

 anterior view. F, Chloridella panamc^isis Bigelow (Stomatopoda), protocephalon 

 and appendages, ventral view. G, same, protocephalon detached from carapace 

 (Cp), dorsal view. 



a, primary (dorsal) articulation of mandible; lAnt, first antenna (antennule) ; 

 2 Ant, second antenna; Bnd, basendite ; c, secondary (anterior) articulation of 

 mandible; Cp, carapace; Cxpd, coxopodite; d, anterior (ocular) division of 

 protocephalon ; E, compound eye ; e, ocular plate of protocephalon ; Epst, epi- 

 stoma ; Expd, exopodite ; /, postocular dorsal plate of protocephalon ; g, pos- 

 terior (antennular) division of protocephalon; /, /, dorsal promoter and re- 

 motor muscles of mandibles; II -VIII, second to eighth somites; k, adductor 

 ligament of mandibles ; KL, adductor muscles of mandibles ; Lm, labrum ; Prtc, 

 protocephalon; r, rostrum of mandibular somite; Tlpd, telopodite (palpus). 



