EiXjdanation of Plates. 35 



appruacbiii^ to maturity ; its pedunculate eyes, two pair of antennae, clypeus, 

 feet and posterior extremity almost fully developed. 



Fig. 13. The last or eightli pair of feet in the male, magnified, x indicates 

 the situation of those organs in the male which occupy the place of the 

 female receptacle, fi^. 14. One of these organs (the left) more highly mag- 

 nified, X its point of attachment. 



Fig. 15. Magnified sketch of the Heart and great blood vessels, the arrows 

 indicating the course of the circulating fluid, a, the stomach, lying over the 

 anterior aorta, and obscuring its further course towards the head, h, heart, 

 r, posterior aorta. /, indicates the line of the posterior part of the clypeus. 

 d, d, presumed vena; cavae. e, e, what seems to be a receptacle placed be- 

 neath the heart. The two lateral vessels which are seen entering the heart, 

 are probably the trunks of the pulmonary veins, coming from the branchiae. 

 The great transparency of this species, (M. vulgaris,) particularly when 

 young, permits all this to be seen withour dissection. 



N. B. In order to avoid the unnecessary multiplication of plates, and as 

 the remaining members of the mouth, and the valvular pouch, are similar 

 in M. Chamaeleon, these parts have been copied after that species, and 

 will be found in the following Plate. 



Plate lIIl.Fig. 1. Anterior extremity of the female Mysis Chamaeleon, highly 

 magnified. 1 a, superior antenna;. 2 a, inferior antennae, c, corselet, e, eye. 

 s anterior scales. 



Fig. 2. Posterior, extremity of the same somewhat more magnified, to 

 shew the peculiar form and armature of the middle scale, as well as the shape 

 and admirable plumose fringe of the outer ones. 



Fig. 3. The last joint of the inner division of the second pair of feet, very 

 highly magnified ; a small circle on the left indicates its natural size, and 

 the line on the right the length of the full grown animal. I'his very beauti> 

 ful member, may be observed to end in a strong spine above, to have its 

 front armed with a gradation of hooks, its back bristly, and its margin 

 surrounded by a graduated row of bi-articulate fiattish spines, most elegantly 

 toothed on their opposite edges. It is hardly possible to do justice in such a 

 sketch, to the complication, and extreme elegance of this wonderful little 

 hand. 



Fig. 4. One of the first pair of maxillae, highly magnified, from the right 

 side, (as seen from within,) foliaceous, complicate, and variously ciliated : 

 / the analogue of the flagrum, placed at its outer edge. 



Fig. 5. One of the second pair of maxillae, from the same side, (also from 

 within,) its middle division with a double row of teeth, its inner division, 

 ending in three denticulate spines./, analogue of the flagrum. 



Fig. 6. Mandible and Palp of the left side, highly magnified, as seen 

 from without, a, fulcrum for muscular attachments: m, acting part of the 

 mandible and its toothed extremity, p. Palp, (as in Plate f. fig. 4) attached 

 to the angle of the mandible. 



Fig. 7. Labrum, highly magnified. 



Fig. 8. Labium, highly magnified. 



