ii6 



PATTEN AND REDENBAUGH. 



[Vol. XVI. 



The second joint is moved by two muscles. A large flexor 

 (y.^) arises from the anterior side of the proximal joint, and 

 is inserted upon the inner proximal margin of the second. 

 A smaller extensor muscle {e.^) arises from the outer and pos- 

 terior sides of the proximal joint, and is inserted upon the outer 



„.--man. 



"TTi.-n. 

 --i.Tnan. 



Fig. 2. — Diagram showing muscles and distribution of nerves in the tliird leg of Limulus, from the 

 anterior side (Ji natural size). 



l-cox., coxopodite, or first joint; 3-bas., basipodite, or second joint; 3-isc., ischiopodite, or 



third joint \ 4-\ ' fused carpopodite and meropodite, or fourth joint ; 5-pro., propodite, or 



fifth joint; b-dac, dactylopodite, or sixth joint; a^o., apodeme ; h.c, haemal side of carapace ; 

 ^«(/(j., endocranium ; ///., heart ; t'«/'., intestine; z'.»?a«., internal mandible ; »«., mouth; man., 

 mandible; /., pericardium; p.s., pericardial sinus. 



Muscles : 3 a and ^, plastro-coxal muscles inserted upon anterior side of entocoxite ; 

 jcandd, tergo-coxal muscles inserted upon anterior side of entocoxite; ^. 2-6, extensors of 

 second to sixth joints ;y.2-6, flexors of second to sixth joints ;/■.>", flexor of inner mandible. 



Nerves: a.e.n., anterior ento-coxal nerve; br., brain; (?./.?2., external pedal nerve, /(., 

 haemal branch of integumentary nerve; A. «. 3, haemal nerve; j«.«.5, integumentary branch; 

 «./.«., internal pedal nerve; >«.^.«., median ento-coxal nerve ; >«.«., mandibular nerves ; «., 

 neural branch of integumentary nerve ; «.«.3, neural nerve ; p.e.n., posterior ento-coxal nerve. 



