Jheringula paulensis, a new generic Type of Macrothricidæ. 21 



In gamogenetic females, as stated above, the dorsal part 

 of the carapace sometimes assumes a very dark hue; but 

 this is wholly due to the ephippium. 



Inner organs. 



The intestinal tube (see PI. I, fig. 1) is quite simple, 

 without any cœcal appendages or coils, extending trough the 

 axis of the body, and forming a double sigmoid curve. The 

 anterior part, contained within the head, is slightly dilated, 

 and curves downwards, joining, at about the centre of this 

 division, the narrow and very muscular œsophagus, which 

 «xtends obliquely forwards from the mouth. The posterior 

 part of the tube enters the tail by a strong curvature, and 

 terminates in a short muscular rectum, which debouches 

 at the posterior edge just behind the infero-posteal corner. 



The heart is easily observable in the living animal, 

 owing to its rapid pulsations, and occupies its normal place 

 dorsally in the foremost part of the carapace, where the 

 body passes into the shell. It has an almost transverse po- 

 sition (see PI. II, fig. 1), and is oval in form, exhibiting on 

 each side a distinct fissure for the entrance of the blood. 



Of the nervous system, the pre-oral part, lying within 

 the head, is not difficult to observe (see PI. U, fig. 1). The 

 cephalic ganglion is located between the anterior part of the 

 intestinal tube and the ventral edge of the head, and con- 

 sists of 2 symmetrical halves connected in the middle. In 

 front it sends off the short and thick optic nerves, which 

 anite at the end to form the optic ganglion. From this 

 numerous nerve-fibres pass to the eye, forming together a 

 dense bundle, which, in the lateral view of the animal, are 



