THOEACIO APPENDAGES 133 



podite, and dactylopodite. Of these the mero- 

 podite and the propodite are the longest, and 

 the dactylopodite is clawHke. 



XIII. This, the last thoracic leg, differs from XII. in 

 having no giU. In the male the coxopodite is 

 perforated at its inner angle by the genital pore. 



XI. This resembles XII., but the propodite is pro- 

 longed distally so as to form with the dactylo- 

 podite a pjiir of pincers or chelae. The inner 

 angle of the coxopodite is perforated by the 

 genital pore in the female. 



X. This is like XI., but has no genital pore. 



IX. This is similar to X., but much larger and stouter, 

 the terminal chelaa being especially large and 

 powerful. The basipodite and ischiopodite are 

 firmly fused together, as happens occasionally in 

 other limbs of the series. 



The anterior group of thoracic appendages, or maxilli- 

 ^edes, can be more easily removed if the anterior portion of 

 the branchiostegite be first cut away. 



VIII. The third maxiUipede is directed forwards under 

 the five appendages in front of it. 

 i. The protopodite consists of coxopodite, bearing 

 a gill and coxopoditic setse ; and basipodite, 

 bearing endopodite and exopodite. 

 ii. The endopodite consists of five joints, named as 

 in the l«gs. The first joint or ischiopodite is 

 the largest and is fused with the basipodite. 



Tig. 33.— Astaous fluviatilis var. nobilis. The oral appendages of the 

 right side seen from below and behind ; x 2^. (c. h. h.) 



Ill, the mandible. IV and V the first and second maxillae. VI, VII, 

 and VIII, the three maxillipedes. 



A, region of attachment to body-wall. A B and AD, points of insertion of 

 abductor and adductor muscles of mandible. B, basipo(ite. C, carpopodite, 

 CX, coxopodite. D, dactylopodite. E, epipodite. F, pivots of mandible. 

 G-, gill. H, coxopoditic setse. I, iscMopodite. M, meropodite. M", endo- 

 podite. P, propodite. S scaphognathite. X, first joint of exopodite. 



