EXPLANATION OF PI^ATp: VI, 



Figs, i — 6. — Specimens of Dichelaspis angulata from the Bay of Bengal — 



Figs. I, la, 2. — Form with short, stout scuta, with or without a carina, 



with relatively large chitinous points. 



, , 3. — Form with a rudimentary carina and with slender scuta, the lower 



extremities of which are produced into a fine chitinous filament. 



,, 4. — Form without a carina, with the scutum markedly sinuous ; the 



aperture transverse. 

 ,, 5 J 5^- — Form with stout, curved scuta and a vv^ell-developed carina. 

 ,, 6. — Forms with slender scuta with distinct basal branches; carina 

 rudimentary. 

 ,, 7 — 10. — Specimens of Dichelaspis cor from a single crab, illustrating variation 

 in the direction of the aperture and in the concentric lines on the 

 external surface of the capitulum. 

 II — 13. — Specimens of Dichelaspis geryonophila from the Laccadive Sea (from 



Geryon affinis). 

 14, 15. — Specimens of Z). geryowo/)Ma from Martha's Vineyard, New Jersey. 

 All these individuals are from one specimen of Geryon quinquedens, 

 but those represented in fig. 15 are the types of the variety 

 fissicarina. 



