JONESIELLA. 39 



pairs having both branches composed of three joints ; 

 basal joint of the fifth pair very broad, second joint 

 smaller. One ovisac. 



Seen from the side these animals have much the 

 appearance of the genus Ectinosoma, the first body- 

 segment being small and tapering towards the front, 

 the abdomen also slightly tapering and extended per- 

 sistently nearly in the axis of the cephalothorax ; the 

 structure of the swimming-feet is also very similar, 

 but the mouth-organs are entirely different. I have 

 much pleasure in naming the genus after my old and 

 valued friend, Prof. T. Rupert Jones, one of the 

 first and most zealous workers amongst the fossil 

 Entomostraca. 



1. JONESIELLA FUSIFORMIS (Brady and Robertson). PI. 



XLVIII, figs. 113. 



Zosime fusiformis, B. & R. Brit. Assoc. Report, p. 196 (1875). 



Body elongated, slender ; head and first thoracic 

 segment coalescent, produced into a slender rostrum. 

 Anterior antenna 7-jointed, short, the last four joints 

 short and densely clothed with long hairs (fig. 2), 

 some of which are strongly pectinate or plumose ; the 

 fourth joint bears a long rod-like appendage (fig. 2 a), 

 and the fifth a peculiar, branched, spine-like seta 

 (fig. 25). In the male the antenna is irregularly 

 corrugated, and has a large vesiculiform swelling of 

 the fourth joint (fig. 3). Posterior antennae stout, 

 and armed on the second joint with several short 

 spines, some of which have pectinate margins (fig. 4), 



