Mr H. D. S. Goodsir on two New Species of Leachia. 313 



membrane which closes the vault of the marsupium of the 

 fourth thoracic segment. From the last of the thoracic gan- 

 glia, a delicate filament on which ganglia could not be dis- 

 tinctly made out, passes along between the bases of the bran- 

 chial or abdominal feet. The muscular system in this genus 

 presents nothing peculiar, except the highly-developed and 

 distinctly-defined longitudinal muscles, two in number, which 

 stretch along the dorsal aspect of the elongated fourth tho- 

 racic segment. These are arranged for the purpose of enabling 

 the animals to erect the anterior part of the body on the true 

 thoracic legs, and of affording a purchase for the proper action 

 of the powerful-clawed antennae. The intestinal system con- 

 sists of the simple mandibles and the maxillary feet, of a di- 

 gestive tube moderately dilated along the fourth thoracic seg- 

 ment, but bulging considerably at its posterior part, and ter- 

 minating in a delicate intestine, which opens at the anterior 

 part of the vault formed by the last abdominal segment be- 

 hind the last pair of branchial feet. The liver exhibits itself 

 in the form §f two elongated yellow granular masses on each 

 side of the stomach. The dorsal vessel or heart was indis- 

 tinctly seen along the posterior part of the back, and may 

 be considered as communicating in the usual way with the 

 branchial organs, which are, in the family to which this genus 

 belongs, developed in the sides of the abdominal feet. 



I am not acquainted with the characteristics of the male, 

 almost all the specimens procured having eggs in the marsu- 

 pium. The eggs are pear-shaped and curved, have a tough 

 external membrane, a granular white, and alight yellow mass 

 towards their centre, which may be of the nature of the yelk 

 globules. The ovaries are two elongated white granuUu* 

 bodies on each side, and beneath the liver. They open at 

 the third thoracic segment, at the extremity of the marsupium. 



Explanation of Plate VI. 



Fig. 1. Leachia intermedia. 



... 2. Its superior and inferior antennse. 



... 3. Its fourth thoracic segment. 



... 4. Leachia gracilis. 



... 6. Its superior and inferior antenn». 



..T 6. Its fourth thoracic segment. 



... 7. Nerrous system. 



