49 



Fig. 4. Outline of maxilliped (7th cephaletral limb) . 



1-5, as in fig. 3. r. Flagellum. 



6. Lamelligerous joint. s. Cnemial appendage. 



7. Chelate extremity. t. Terminal lamellae. 



Fig. 5. Mandibula (4th cephaletral limb) dissected for the muscles. 



a. Extensor basis maudibulae. e. Propedal entapophysis. 



b. Flexor basis. /. Flexor propedis. 



c. Merional entapophysis. g. Flexor dactyli. 



d. Flexor merioui cuemiique. 



' Plate III. 

 Limulus polyphemus. 



Right half of the male King-crab, with the nervous system dissected from the ventral surface. The 

 explanation of the parts in tliis figure is given in the outline copy in Plate IV. 



Plate IV. 

 Fig. 1. Outline of figure 1 in Plate III., showing the nervous system, from the lower or ventral aspect. 

 a'. Inferior concave surface of cephaletron. n xv. Nerve of anal segment. 



b'. Infero-lateral sui-face; b" Infero-median but- (x^e other letters and figures as in Plate II a.) 



face of thoracetron. 



Fig. 2. Compound eye and terminations of ocular nerve, from the dorsal aspect : magnified 6 diameters 

 {Limuh(s polyphemus) . 



d. Dorsal branch and divisions of ocular nerve. v. Ventral branch and divisions of ocular nerve. 



Fig. 3. Compound eye of a Trilobite [Phacops conophthahnus) : magnified 3 diameters. 

 Fig. 4. Portion of the same compound eye : magnified 10 diameters. 

 Fig. 5. Entosternon and attached parts of muscles. (After Van der Hoeven, op. cit.). 

 Fig. 6. Chief parts of ovarium, oviducts, and opercular plate, from the upper or inner surface {Limulus 

 polyphemus) . 



»i". Muscles of operculum. q**. Postero-lateral cephaletral branches. 



0, o. Oviducts. r. Articular surface of opercular plate. 



p. Oviducal outlets. 2. Second joint of opercular plate. 



q. Postero-median lobe of ovary. 3. Third joint of opercular plate, 



y*. Antero-median lobe of ovary. 4. Appendages of opercular plate. 

 q" . Antero-lateral loops and branches. 



Fig. 7. Section of terminal part of oviducts. (After Van der Hoeven, op. cit.) 



a. Oviduct; 6, anterior labium ; c, portion of opercular plate. 

 Fig. 8. Portion of opercular plate with terminations of the sperm-ducts, p. (After Van der Hoeven, op. cit.) 



Plate V. 



Limulus polyphemus. 



Fig. 1. Nervous system, from the upper or dorsal aspect. 



a. SupercEsophageal mass. b. (Esophageal ring 



H 



