Jheringula pauleneis, a new generic Type of Macrothricidæ. 19 



most straight and parallel to each other, the end being 

 transversely truncated. To the anterior corner the compara- 

 tively small caudal claws are attached, each having the con- 

 cave edge minutely spinulose. The whole posterior, or dorsal 

 edge, as also the terminal one behind the caudal claws, is 

 densely clothed with short hairs, which at each corner as- 

 sume the character of dark-coloured spinules. To the some- 

 what projecting upper corner of the tail the caudal setæ are 

 movably attached. They are rather strong, about the length 

 of the whole tail, and extend obliquely upwards, diverging 

 somewhat to each side (see PI. 1, fig. 2). As usual, they 

 each consist of 2 joints, the distal one, however, being very 

 short, and clothed with long diverging hairs in a brush-like 

 manner. The tail does not admit of being wholly withdrawn 

 into the shell, the part adjacent to the caudal setæ always 

 projecting beyond the hind edges of the valves (see PI. 1, 

 fig. 1). Above the tail, the dorsal face of the enclosed body 

 forms an obtusangular projection, which generally applies it- 

 self closely to the inside of the shell dorsally, thereby clo- 

 sing the incubatory cavity behind. The concave dorsal face 

 of the body in front of this projection does not exhibit any 

 such mammilliform prominences as in the species of the genus 

 Macrothrix. 



Gamogenetic females do not seem ever to reach 

 the size of parthenogenetic specimens, scarcely exceeding a 

 length of 1 mm. They are (see PI. I, fig. 3) easily re- 

 cognized by the sharply defined and coarsely reticulated ephip- 

 pium, which occupies the greater part of the carapace and, 

 when fully developed, assumes a very dark, almost black 

 colour. Seen laterally (fig. 4), the ephippium is transversely 

 oval in form, being considerably deeper than it is long, and 

 has the dorsal, thickened margin nearly straight, terminating 



I 



