770 PROF. T. H. HUXLEY ON THE CLASSIFICATION [June 4, 



There are only a few very small hooked papillary elevations on 

 the epipodite of the first maxillipede ; in fact the podobranchia is 

 reduced to nearly the same condition as in Astacus. The hooks of 

 the setae are very slender. 



The branchial formula is the same as in Astaeopsis and Ch&raps, 

 viz. : — 



Somites podQ _ Arthrobranchi*. pleup ^ 



and their branchiaJ- *-— *— -> branchiae. 



appendages. Anterior. Posterior. 



VII (ep r) 0=0 (ep r) 



VIII I 1 0=2 



IX 1 1 1 0=3 



X 1 1 1 0=3 



XI 1 1 1 1=4 



XII 1 1 1 1=4 



XIII 1 1 1 1=4 



XIV 1=1 



6 + ep r + 6 + 



+ 



21+ epr. 



6. The Branchice of Paranephrops. 



In Paranephrops planifrons I find the branchiae to have the same 

 general character and disposition as in Astaeopsis and Engaus. 



The podobranchiae are devoid of any trace of a lamina. The 

 branchial filaments on the posterior faces of these branchiae are, for the 

 most part, provided with terminal hooks, while the rest have smooth 

 and rounded apices. 



The anterior arthrobranchiae have not half the size of the podo- 

 branchiae, while the posterior arthrobranchiae are very minute, and the 

 hindermost is rudimentary, being a mere simple filament, like one of 

 the rudimentary pleurobranchiae of Astacus. The pleurobranchiae 

 are larger, but the three anterior ones are small. None of these 

 branchiae have hooked papillae. 



The external and posterior face of the epipodite of the first maxilli- 

 pede is beset with short hooked branchial filaments. 



The coxopoditic setae are few, slender, short, and hooked at the 

 extremity . 



The Branchial formula of Paranephrops. 



So ^ CS Podo- Arthrobranchi«. pleuro _ 



and their branchi£e .7—^—- branchi*. 



appendages. Anterior. Posterior. 



VII 0(epr) = (ep r) 



VIII 1 1 0=2 



IX 1 1 1 0=3 



X 1 1 1 0=3 



XI 1 1 1 1=4 



XII 1 1 1 1=4 



XIII 1 1 r 1 3 + r 



XIV 1=1 



6+epr+6 + 4 +r + 4 = 20 + epr + r. 



