﻿PLATE XXXIV. 



Order — Merostomata. 



Sub- Order — Xiphosura. 



Anatomy of Limulus polyphemus, Latr. (after Owen). (Pp. 186 — 209.) 

 Figs. 



1. Side-view of heart, alimentary canal, and nervous system (seen in a longitudinal 



section). 



A. Cephalon (" Cephaletron," Owen). 



B. Thoracico-abdominal somites coalesced (" Thoracetron," Owen). 



C. Telson (" base of Pleon," Owen). 



A'. Under or vaulted surface of cephalon. 



B". Rudimentary abdomen ("anal segment of Thoracetron," Owen). 



i. The compound eye. a 1. Ocelli, n. Antennule. in. Antenna, iv. 

 Mandible, v. First maxilla, vi. Second maxilla. [In Pig. 1 the forci- 

 pated foot of the maxilliped vn has not been indicated by the artist, but 

 see vn, Pig. 2.] vn. Maxilliped. vin. Operculum, ix — xin. The 

 five branchial feet. 

 b. Dorsal wall of cephalon. c. Ventral wall of cephalon. d. Digging border 

 of head-shield, e. Holding border of cephalon. /. Plinder border of 

 cephalon. g. Entering process of thorax, h. Entosternon. i. Intestine. 

 m 1. Levatores thoracetri. m 7. Levatores telsoni. m 8. Obliqui 

 telsoni. m 9. Depressores telsoni. n a. Ocellar nerve, n a. Ocular 

 nerve, n n. Antennular nerve, n in. Antennal nerve, n iv. Mandi- 

 bular nerve, n v. Premaxillary nerve, n vi. Maxillary nerve, n vn. 

 Maxillipedal nerve. 



2. Section through anterior part of cephalon, showing gastric cavity and buccal orifice 



with maxillipeds, numbered as in Pig. 1. (Pp. 190, 201, 202.) 



3. A detached maxilla showing the articulations and the palpus. (P. 186.) 



4. A detached maxilliped (for nomenclature of joints see p. 6, Part I, of this 



Monograph). (P. 190.) 



5. Section of one of the maxillse to show the muscles. (P. 187.) 



