12 



on the thoracic legs (only m some species of Ealiporus is there a rudimentary 

 podobranch on the 1st pair). Arthrobranchiaa in a double series. 



II Arist2Ein;e. No leaf-like appendage on the inner border of the basal 

 ioint of the antennular peduncle. Bxopodites are present on the 1st and 2nd 

 maxillipeds, but are usually absent-or, if present, are of very small size, on the 

 thoracic legs. Podobranchi* are present on the first two or three pairs of 

 thoracic legs. Arthrobranchise in a double series. 



III SicYONiNiE. No leaf-like appendage on the inner border of the basal 

 ioint of 'the antennular peduncle. No exopodites to any of the thoracic append- 

 ages behind the 1st maxillipeds. No podobrancmse. Arthrobranchue m a 

 single series. 



II. 



Key to the genera and sub-genera of Peneida3 of the Indian Necton. 



The inner border of the 1st segment of the antennular peduncle carries a 

 twisted setose scale that forms an incomplete inner wall to the orbit. 

 No podobranchise on any of the legs :— 



1. Antennular flagella cylindrical :— 



i. The 2nd joint of the mandibular palp is vastly larger than 



the 1st and forms almost the whole palp : the exopodites 



of the external maxillipeds are large 

 ii. The 1st joint of the mandibular palp is a good deal larger 



than the 2nd: exopodites of the external maxillipeds 



rudimentary or absent 



2. Antennular flagella thin, broad, compressed : (the 2nd joint of the 



mandibular palp much larger than the 1st: exopoditeB of the 

 external maxillipeds very short and slender) : — 



i. The sub-foliaceous antennular flagella are truncated 

 ii. The sub-foliaceous antennular flagella gradually taper to a 

 lash 

 The scale on the inner border of the 1st segment of the antennular peduncle 

 is absent or quite rudimentary. Podobranchiaa are present on the first 2 



or 3 pairs of legs : — 



1. The outer (upper) antennular flagellum is extremely short, the 

 inner (lower) flagellum is long: the 1st joint of the mandibular 

 palp is much longer than the 2nd, but though it is compressed and 

 broad, it is not foliaceous : — 



i. No hepatic spine : rostrum dorsally 3-toothed (rarely 2-4 



toothed) : — 

 a. The 3rd pair of legs have an epipodite but no podo- 

 branch, the 4th pair have no epipodite : — 



a. Cervical groove indistinct : the pleuro- 

 bvanchise in advance of somite xiv are 

 mere filaments or papillae 

 Cervical groove fine but conspicuous: the 

 pleurobranchise in advance of somite 

 xiv, though small and slender, are 

 plumose and functional ... 



Peneus. 



Halipoeus. 



SOLENOCEEA. 



Parasolenocera. 



0. 



ARISTAK0S. 



Hemipeneob. 



