Descnption of Genera and Species. -^3 



gradually. They are all more or less welded together ; but the division lines are 

 still very distinct and the test at these parts appears to be folded well inwards to give 

 lateral rigidity, and there is an arching of each segment so as to produce a sort of 

 interrupted blunt median crest. The arrangement is almost identical with what takes 

 place in ry(joceplialus cooperi, as described by Huxley/ and which is so characteristic of 

 this group of Schizopods (pi. iv., figs. S, 9)". That these sternites were only imperfectly 

 soldered together is shown by some of them being displaced. This specimen (fig. 2) also 

 helps to show that the carapace was quite free from these segments and only loosely 

 covered them, for the long axis of the sternum does not agree in direction with that 

 of the carapace. Another point is illustrated by this specimen, and by fig. 3, viz., 

 that the carapace nuist have extended laterallv far bevond the bodv walls of these 

 segments. 



The tail is flattened and shorter than the carapace, and the first segment appears 

 to have almost touched the carapace in the mid-line of the back, as shown in fig. 3, so 

 that only a very sliglit part of the last trunk segment could be exposed. The first tail 

 segment is nearly as wide as the posterior part of the carapace, and the epimera seem 

 to have been small. Part of the second tail segment is also shown in this figure, and 

 reveals the width of its sternite between the bases of the pleopods. In this specimen 

 the other segments are shown edgeways, so that the natural arch of the back and the 

 epimera are thus prol^ably indicated. The dorsal aspect of the last four tail segments 

 is shown in fig. 5, as well as the telson and the left pair of uroj)ods. The segments 

 are all much alike, very wide compared with their length, with wide-apart pivots and 

 well facetted anterior margins for rolling, with a smooth area in front arid an embossed 

 band behind set with backwardly-directed flattened spines, and with widely spread, sharp, 

 triangular-shaped epimera. Each segment has also a narrow smooth band along its 

 posterior margin. There are also two rows of short transverse kej-hole-like slits bordered 

 by a smooth flattened edging, two placed on each segment in advance of the pivots, 

 and also upon the telson behind, the rows gently converging backwards as if the general 

 axis of the tail were also narrowing in tliat direction, although this is barely appareiu 

 to judge by the epimera. There is a trace of a median ridge or longitudinal keel upon 

 all the four segments, which reappears in tlie telson and its terminal lobe. The telson 

 is triangular or leaf-shaped, with its broad base articulated with the sixth segment. 

 Its sides are produced into denticulated lobes, and it terminates in a central heart-shaped 

 lobide which appears as if it were articulated with it. The telson is ornamented with a 



' Quart. Jouiii. Geol. Soc, IS.JT, vol. xiii., p. 363, [il. xiii., ligs. 1-3. 

 - Reproduced from liiixley'.-i ori<;iiial figures for couipari.son. 



