AMPHIPODA OF SOUTHERN NEW ENGLAND. 4(>3 



rami, which arc generally uniarticulate, although in .some forms the outer ramus 

 consists of two joints of which the terminal one is usually small. Both peduncle and 

 rami arc generally armed with strong spines along the upper margins and at the tip. 

 The terminal pair of uropods is frequently quite different in form as well as size from 

 the preceding pairs. The outer ramus is sometimes greatly elongated while the 

 inner one is rudimentary (Melita, Niphargus, and a few other genera). In many 

 genera the inner ramus is completely lacking ( Orehestia, < 'orophvum, the Stenothoidiv). 

 A great many amphipods. on the other hand, have the outer ramus of all the uropods 

 shorter than the inner one. Very rarely ( < i rapus) the second uropods are uniramous 

 as well as the third. In Pereionotus the uropods are reduced to two pairs. The 

 Caprellidse, owing to the rudimentary condition of the abdomen, possess at most two 

 pairs of abdominal appendages, and these much reduced in size. In some members 

 of this group the abdomen is entirely devoid of appendages. 



GUIs. — The gills of amphipods are in the form of flattened sacs which depend 

 from the inner side of the coxal plates of the thoracic legs. They are usually 

 confined to the last six pairs of thoracic appendages, but are lacking in different 

 segments in different groups. 



Marsupial pouch. — The eggs of the Amphipoda are carried in a pouch under the 

 thorax of the female. This pouch is formed by overlapping lamellae which arise 

 inside the base of the second to the fifth thoracic appendages. In some forms there 

 are less than four plates, hut it is very rare that there are rive. Each lamella is gen- 

 erally more or less spatulate in form and bears on the margins very long plumose 

 setae, which serve to hold the plates together. 



The following abbreviations are used in connection with the figures in the text: 



ant) first antenna. p perseopod. 



nut.. second antenna. T telson. 



gn gnathopod. ur uropod. 



Tribe HYPERIIDEA. 



Head generally large, often with enormously developed eyes; maxillipeds with the inner plates 

 coalesced; palp wanting; gnathopods not very large, coxal plates small; last two abdominal segments 

 fused. 



The Hyperiidea are pelagic forms and are often found in association with medusa', or, more 

 rarely, other pelagic animals. The species often have a very wide range, and it would not be surpris- 

 ing, therefore, if forma were met with off the coast of New England which had previously been 

 recorded only from a far distant locality. Nearly all the known species of Hyperiidea are fully 

 described and figured in the excellent Monograph of the Amphipoda Hyperiidea by Prof. Carl Boval- 

 lius. The species that have been met with near the coast of southern New England are described 

 below. 



Family HYPERIID.-E. 



Head very large and tumid, the sides entirely occupied by the enormous eyes; antenna? short 

 and with undivided flageilainthe female; with long multiarticulate flagella in the male; mandibles 

 with :t palp; gnathopods simple, subchelatej <>r complexly subchelate; perseopods not greatly modified; 

 uropods biramous, with flattened lanceolate rami. 



Perseopods subutjual in length. 



Carpal lobe of the iirst gnathopods short or absent Hyperia 



i larpal lobe of the tirst gnathopods us long us tin- propodus '. Hvpeeoche 



Third perseopods markedly longer than tin- others Kt themisto 



