1908] Decapod Crustaceans. 17 
arthrobrancehia, both of which are wanting in the last-named spe- 
eies: again E. acutifrons has no arthrobranchia on its 3rd maxil- 
liped, whereas UC. crassipes has a well-developed arthrobranchia 
on each side. Otherwise the numbers of the branchiae correspond. 
Podobranchiae and arthrobranchiae are equally wanting on the 2nd 
maxilliped in Paraxius altus: but on the other hand on the 3rd 
maxilliped of this species and also of U. crassipes there is å pair 
of arthrobranchiae. 
The same is the case with Calastacus Cf. Warter Faxon: 
*Report on the Dredging Operations off the west coast of Central 
America. Preliminary Descriptions of New Species of Crustacea, 
Bull. Mus. Comp. Zool. at Harvard. Vol. XXIV, 18983. 
Calocaris Macandreae Brrr. on the other hand is identical with 
UC. erassipes in respect of number and distribution of branchiae: 
though the podobranchiae in particular of this species are consider- 
ably more developed. 
The following table shows the distribution of branchiae in the 
different species mentioned:— 
Calocarides erassipes 'Tryb.*) 
Maxilliped Pereiopod 
2nd drd Ist 2nd drd | 4th Sth 
Ashrobranchiae ...-.....25. 1 2 2 2 2 2 0 
BRodopranehnae 1. 1305. 1) 1 1 1 1 0 0 
Mastebbranchiae ......-.. 1 1 il ee TL 0 
Calocaris Macandreae Bell. 
Aihrobranehiae >. ....-0 It 2 2 2 2 2 0 
Bodobranchiae.-....-...... 1*) 1 1 1 0 
Mastieobranchiae .......... ll 1 1 1 1 1 0 
1) All these species are without Pleurobranchiae. 
*) rudimentary. 
