No. I.] 



STUDIES ON LIMULUS. 



119 



i.m: 



Fig. 3. — Diagram showing the muscles and distribution of the nerves in the sixth leg of Limulus, 

 from the anterior side (% natural size). 



i-cox., coxopodite, or first joint ; 2-bas., basipodite, or second joint; $-isc., ischiopodite, or 

 third joint ; 4- j ^^^J^' fused carpopodite and meropodite, or fourth joint ; 3-pro., propodite, or 

 fifth joint ; b-dac, dactylopodite, or sixth joint ; apo., apodeme ; br., brain ; c.c, cross-commis- 

 sure ; endo., endocranium ; flab., flabellum ; h.c, haemal side of carapace; hi., heart; int., 

 intestine ; man., mandible ; p.s., pericardial sinus. 



Muscles: 6-' and ^>, plastro-coxal muscles inserted upon anterior side of entocoxite; 

 6c and d, tergo-coxal muscles inserted upon anterior side of entocoxite; e.'^'T, extensors of 

 second to seventh joints ; f.'^~'', flexors of second to seventh joints ; i.m., inter-tergal muscle. 



Nerves: a.^.«., anterior ento-coxal nerve ; (?./.«., external pedal nerve ; /!., haemal branch 

 of integumentary nerve; h.71.^, haemal nerve; i.n.^, intestinal nerve; in.?i.^, integumentary 

 branch of haemal nerve; i.p.n., internal pedal nerve; l.c.n., lateral cardiac nerve; m.c.n., 

 median cardiac nerve ; m.e.n., median ento-coxal nerve or flabellar nerve ; ?«.«., mandibular 

 nerve; «., neural branch of integumentary nerve; «.«.6, neural nerve; p., pericardium; 

 p.e.n., posterior ento-coxal nerve ; s.c.n.^, segmental cardiac nerves. 



