364 Mr Henry Goods! r on some Xew Cnisfaceous Ammah 



narrow, and is not composed of two equilateral pieces, as in 

 the other Aasellola, hut consists of one piece only, with an im- 

 moveahle suture in its mesial line ; it is attached to the hody 

 by means of its proximal extremity only. 



These animals differ also from all the other Isopodous 

 Crustaceans, in the great length of their ambulatory legs, which 

 leads the observer at first to suppose them to belong to the 

 KymphomdcG ; its quick and active habits, however, very soon 

 undeceive him. 



The habits of this species of Manna, like the rest of the 

 Isopcda, are interesting ; it is quick and active in its motions, 

 running along the branches of the smaller corallines with 

 great rapidity. I have never observed it swim ; in fact, it is 

 not adapted to this mode of progression. When pursued along 

 the bottom by any larger animals, or with the point of a 

 needle, it runs quickly before it; but often stops suddenly, 

 turns round, and becomes assailant. 



The eggs are carried in a large oviferous pouch, which is 

 situated betw^een the thoracic legs, and is composed of four 

 large plates, very like those of the Caprellce. I now subjoin 

 M. Kroyer's definition of this genus. 



MuNNA {Kroyer^ 

 " Novum Isopodum Genus (inter Asellota, Latr. prope Jaeram ) . 



" Oculi valde prominentes (fere pedunculati), tota capitis 

 latitudine distantes ; antennae inferiores longissima? ; pedes 

 1 mi paris prehensiles (manu ungueque mobili instruct!), reli- 

 qua 6 paria ambulatoria, longissima (pleraque corporis longi- 

 tudinem superantia), biungulata ; 7 mus thoracis annulus mi- 

 nimus parumque conspicuus ; cauda appendicibus omnino de- 

 stituta ; branchias unica tantum tectse lamina.''* 



In the species winch I have examined of this genus, the 

 tail is not, as Kroyer states, entirely destitute of appendages ; 

 for although minute, they are easily seen with a small power. 

 They are four in number (Plate VI. fig. 14.), one spine at each 

 of the posterior angles of first abdominal segment, and two 

 smaller styles from either side of the apex of the last joint. 



''" Kroyer. Isis von Oken, 18^1, p. 428. 



