8 



posterior antenna- and oral parts. now with quick leaps effected by powerful 

 strokes of the natatory legs and the urosome. It keeps constantly close to the 

 bottom. 



/' -triluit'tun. English and Scottish coasts (Brady. Scott), Gulf of Naples 

 Bsbrecht). 



Fam. 2. Longipediidae. 



('lt<i>-iirt< r*. Body of normal appearance, more or less cylindrical in form. 

 with no sharp demarcation between the anterior and posterior divisions. (Vpha- 

 losoine in some cases distinctly detined t'rom tin- 1 st pedigerous segment ; rostrum 

 lamellar and movably articulated to the cephalic shield. Eye well developed. 

 Anterior antennae short and stout, consisting of a \ery limited number of articu- 

 lations densely clothed with partly spinil'orni setse. Posterior antennae with the outer 

 r.-imus very fully developed, cylindrical, 6- or 7-articulate. Mandibles and maxilke 

 with well-de\ eloped and abundantly setiferous palj>s. Anterior maxillipeds calaiioid 

 in striieture ; posterior ones very delicate, lamellar, and fringed with densely plumoiis 

 set;e. Natatory legs with both rami ,'5-articulate and rather narrow, being armed 

 outside with strong spines, inside and at the tip with long, partly spinifonn seta- 

 1st pair not differing greatly from the others. Last pair of legs with the inner 

 expansion of the proximal joint very small, distal joint well-developed or rudi- 

 mentary, (hisac single or double. 



///>. -In this family 1 propose to comprise the 3 genera Longipedia 



ll.-xsr and ( 'mint'llti Scott, which are undoubtedly closely allied, 

 and together form a natural group of the Arhn-nt/i. It does not answer to the 

 subfamily L<.\K\I\>< iliiinf of Brady, to which a much wider raii^e is given, also com- 

 pri-ing. as it does, the genera Zosirne, l-'rli nn*<n and I !nnl//<i. which in my 

 opinion oiiLdit to be referred to ither families. The most characteristic features 

 of the present family are the unusually full development of the outer ramus of the 

 posterior antennae, the likewise largely-developed palps on the mandibles and 

 maxilla*, and. finally, the peculiar, delicate structure of the posterior maxil- 

 lipeds. In all these characters there is a great similarity between the 'A above- 

 named genera, whereas in other resprctx well-marked differences between them 



are found to exist. 



