EEPOET ON THE PHYLLOCAEIDA. 23 



in the specimen. Its carapace measures 16 mm. in length. The carapace of the other 

 specimen is fully 29 mm. long and 16 mm. high, and thus the total length of this 

 specimen may have been about 40 mm. — a very large size, indeed, as compared with. 

 that of the other known recent Phyllocarida. 



The form of the body (see PI. III. figs. 1, 2) differs considerably from that in the 

 species of Nehalia and Paranebalia, not to spealc of the peculiar shape of the carapace, 

 by the large size of the middle division, the trunk, whereas the posterior part of the body, 

 including the pleon and the tail, is comparatively far less developed and scarcely at all 

 longer than the trunk. 



The carapace is exceedingly large and of a form distinctly deviating from that met 

 with in the other two genera. It is slightly compressed, though somewhat less so than 

 in Nehalia, and covers the greater part of the body, including the cephalic part, the trunk 

 and the greater portion of the pleon, without, however, being connate with the body except 

 along a very limited space in front. As seen from the side (figs. 1, 5) it exhibits an oblono- 

 triangular form, with the dorsal line only very slightly arched, the anterior extremity 

 narrowly rounded, and the posterior extremity produced above to an obtuse angle. The 

 inferior edges exhibit somewhat in front of the middle a strong, almost angular curvature, 

 and behind this curvature they ascend obliquely, without forming any projecting lateral 

 lobe, but joining immediately the posterior edges by a very slight curve. The free edges 

 meet above at an obtuse angle, no intervening incision or emargination, similar to that 

 found in the other known forms, being present (see fig. 6). The rostral plate (see figs. 1, 5) 

 is exceedingly small, but distinctly defined from the carapace. As seen from above 

 (fig. 7) it exhibits a quite regular oval form, with a slight keel running along the middle 

 and terminating in front in a small angular projection. In both specimens it curves 

 straight downwards between the free anterior edges of the carapace, partly closing the 

 anterior opening of the shell as an operculum, but in the living animal it undoubtedly may 

 admit of being raised and lowered to a certain extent, as is the case with the other known 

 forms. As to structure, the carapace is very thin and flexible, almost membranaceous, and 

 semitransparent, but provided with a well-marked external sculpturing, especially very 

 distinct on the carapace of the larger specimen (figs. 5, 6). This sculpturing consists of 

 a system of narrow elevated ridges anastomosing with each other, and forming together a 

 somewhat irregular open network, limiting a great number of angular depressed areas of 

 difi"erent size and form. Towards the anterior part of the carapace this scul^^turing 

 becomes gradually less distinct, and at last wholly disappears, whereas at a short distance 

 from the anterior edge a rather coarse transverse elevation passes down the sides, making 

 at its upper part a sharp curve backwards. In the middle of the dorsal surface (fig. 6) 

 a straight ridge or low keel runs along the carapace from its anterior extremity to the 

 posterior, dividing it into two s}TQmetrical halves, and at the end of the anterior fourth 

 part of the length of the carapace a well-defined obliquely transverse line crosses the ridge 



