14 G. O. Sårs. 



In its general appearance, the animal exhibits a great 

 resemblance to that of Estheria, though on a closer com- 

 parison, some well-marked differences may be stated to exist 

 (see PI. 2', fig. 4, PI. 3, fig. 5). It is attached to the shell 

 in the same manner as in other Limnadiidœ, viz., by a 

 narrow dorsal ligament occurring in the umbonal region, and 

 by the great adductor muscle of the shell traversing the 

 body in the cervical region. 



The anterior part of the head, in front of the deep 

 cervical sulcus, is securiform in shape in both sexes, being 

 produced above to a large compressed prominence curving 

 over the adjoining part of the cervical segment, and termina- 

 ting in a sharp point (see PI. 2, fig. 5). The frontal edge 

 forms in the ocular region a rather slight bulging, and 

 immediately beneath this bulge the fornix of the head 

 crosses the margin on each side, to join . the tip of the 

 rostral projection. The latter is strongly compressed (comp. 

 Pl. 3, fig. 6) and, seen laterally, is of triangular form, carrying 

 on the tip a slender, procurved spine, which, however, seems 

 to be movable to a certain degree, as in the male speci- 

 men figured on PL 3, it was extended straight downwards. 



The trunk is slightly compressed, and gradually tapers 

 posteriorly. It is divided into a series of rather uniform 

 segments, the posterior of which, however, are very small 

 and less distinctly defined. The number of segments amounts 

 to 26 or 27 in ah 1 ; but the 3 or 4 hindmost segments may 

 perhaps more properly be referred to the tail, as they do 

 not carry any branchial legs (see PI. 2, fig. 6). None of 

 the segments are produced, as in Estheria, to setous dorsal 

 projections; but some of the posterior segments have only 

 a transverse series of small spines dorsally. 



