No. I.] 



STUDIES ON LIMULUS. 



21 



REFERENCE LETTERS. 



ab. en. 

 a. c. 

 a. p. 



apo. 

 cap. b. 

 ch. 



ch. m. 

 cr. com. 



h. 



h. «.*-» 

 h.p. 



h. pr. 



171. n.^^ 

 int. 

 I.e. 



I. p. pr. 

 m. 



abdominal endochondrite. 



anterior cornua. 



anterior process of abdomi- 

 nal endochondrite. 



apodeme. 



capsuliginous bars. 



chilaria. 



origin of chilarial muscles. 



cross-commissures. 



foramina. 



haemal division of anterior 

 cornu of plastron of Apus. 



haemal nerves. 



haemal processes of ab- 

 dominal endochondrite. 



haemal processes of plas- 

 tron. 



intestinal nerves. 



integument. 



lateral cornua. 



latero-posterior processes. 



middle division of anterior 

 cornu of plastron of Apus. 



, 4—8 



membrane to which are 

 attached the veno-peri- 

 cardiac muscles. 



marginal ridge. 



neural division of anterior 

 cornu of plastron of Apus. 



neural nerves. 



neural plates. 



neural processes. 



occipital ring. 



oesophageal collar. 



origin of opercular muscles. 



posterior processes of ab- 

 dominal endochondrite. 



posterior process. 

 s. shoulder joining latero-pos- 



terior processes. 

 V. p.in}~* veno-pericardiac muscles. 

 w., X., &")/. points of muscular attach- 

 ment on plastron of Apus. 

 z. membrane attached to pos- 



terior side of plastron of 

 Apus. 



n. pi. 

 11. pr. 

 oc. r. 

 oe. col. 

 op. m. 

 p.p. 



p. pr. 



