Phyllopoda of Australia. 259- 



middle, dorsal margin boldly curved anteriorly, almost 

 straight and obliquely declining behind, venti'al margin 

 evenly curved and passing into the anterior and pos- 

 terior edge without any intervening angle, anterior 

 extremity broader than the posterior. Female with 

 rostral expansion in front view very bi'oad, obtusely 

 rounded at the extremity, without any lateral projec- 

 tions ; that in the male transversely truncated, lateral 

 corners scarcely produced. — mackayana. 



2. Shell less tumid than preceding species, in lateral view 



subcircular, nearly as high as it is long, dorsal margin 

 sloping rather steeply behind, anterior extremity very 

 broad and blunted, posterior narrow and rounded. 

 Rostral expansion in female much produced, frontal 

 view, narrow linguiform, with a distinct notch on each 

 side of the obtusely rounded tip ; in the male with 

 distal lateral edges projecting beyond the apical face. — 

 tatei. 



3. Form of shell resembling the preceding one, but with 



posterior extremity much more narrowly rounded. 

 Rostral expansion in both sexes shorter and more 

 constricted in the middle than either of the former 

 species ; that of the female notched on each side near 

 the apex ; in the male rapidly expanding distally,. 

 lateral edges not projecting beyond the face. — ereinta. 



TERMINOLOGY AND EXPLANATION OF PLATES, 

 XXVII.-XXXVI. 



Divisions of Body : 



C. Cephalon (1. Head segment. 2. Cervical Segment). 

 Ms. Mesosome or Trunk. T Metasome or Tail. 



Appendages of Cephalon : 



A^ Antennulae or first antennae. A". Antennae or second 

 antennae. F. A. Frontal appendages of Branchipodidae. 



