11 



The coxopodite of the 2nd maxillae is cleft into two lobes, the distal one of 

 which is prominent, the proximal one small and receding. 



The endopodite of the 1st maxillipeds is long and sometimes five-jointed. 



The last joint of the 2nd maxillipeds is a distinct dactylus, articulating 

 end-on with the distal end of the projjodite. 



The external maxillipeds are distinctly seven-jointed. 



The 3rd pair of thoracic legs are chelate — and often the 1st and 2nd 

 pairs also. 



The endopodites of the abdominal appendages from the 2nd to the 5th 

 have no internal appendix at their base, except in the case of the 2nd pair of 

 the male. 



The branchiae are dendrobranchife. 



Key to the families of Peneidea. 



I. The last two pairs of thoracic lega are well developed : the branchia? 



are usually numerous ... ... ... ... Peneid2E. 



II. The last two pairs of thoracic legs are reduced iu size, or rudimentary 

 — one or both pairs are sometimes wanting : the branchiae are never 

 more than eight on either side and are sometimes absent ... Sergestid.e. 



Family Peneidw, Spence Bate. 



I'eneidx, Spence Bate, Challenger Crnst. Macrura, p. 220: Stebbing, Hist. Crust, p. 213 : Ortmann.in Bronn's 

 Thier Keich, Artbropoda, p. 1118. 



Rostrum usually well developed, laterally compressed : ophthalmic somite 

 little exposed. 



The basal joint of the antennular peduncle is dorsally concave for the eye 

 and is strengthened at base, on the outer side, by a spine-like scale : the anten- 

 nular flagella are two in number. The antennal scale is broadly foliaceous. 



The first three pairs of thoracic legs are chelate, the 4th and 5th pairs are 

 well developed. Exopodites may be present on some or all of the thoracic legs, 

 or may be entirely absent. 



The epipodite of the 2nd maxillipeds is large. The branchiae are numerous. 



The Peneidse may be divided into 3 subfamilies (excluding the claims of the 

 larval form known as Ceratas±ns), as follows : — 



I. Penein.e'. A long setose leaf-like appendage, acting as a sort of pro- 

 tection to the eye, is present on the inner border of the basal joint of the 

 antennular peduncle. Exopodites are present on the 2nd maxillipeds, and 

 usually also on the 3rd ; they are usually present on the thoracic legs, but are 

 sometimes absent from some or all of them. Podobranchia? are never present 



