MODIFICATIONS OF STRUCTURE IN DECAPOD CRUSTACEA. 229 



i. e. of the same relative length as in A. symnista and A. 

 microps. 



Third maxillipeds. The carpal lobe is not produced beyond 

 half the length of the propodite (in this agreeing with A. 

 microps). 



Optic peduncles scale-like^ elliptical, broader than long, 

 presenting a deep emarginatiou at their autero-internal angles 

 which lodges the cornea. The peduncles occupy the lateral 

 compartments of the median emarginatiou of the frontal area, 

 which may accordingly be termed the orbital emargination. 



Telson in the ^ somewhat like that of A. microps, but 

 more elongated and slender, the broadest part being a little 

 nearer the base of the telson, and the sides more distinctly 

 concave. No transverse rows of hairs on back of telson like 

 those in A. microps and A. Guerinii; but a double ad- 

 median longitudinal series, and a group at each of the basal 

 angles. 



This new species approaches in certain features the species 

 Albunea scutellata, described by Milne-Edwards (1834, 

 ii, p. 204, pi. 21, figs. 9 — 13), which, with two other forms 

 (venusta and myops), has been referred by Stimpson to a 

 new genus, Lepidops (1858, p. 230; Miers, 1879, p. 231). 

 These features are — (1) the absence of frontal denticulations; 

 (2) the broad, scale-like optic plates. In fact, were it not for 

 his remark concerning the truncation of the optic plates, 

 Milne-Edwards^ short description would be perfectly applicable 

 to the present species. His figures, however, are not appli- 

 cable. In his figure the carapace breadth is greatest in front ; 

 in ray specimen it is greatest across the middle (as in A. 

 microps). He figures no accessory joint to the antenna; 

 and if the truncated plates in front of the carapace represent 

 the optic plates, as his account implies, the possible identity 

 of the two forms is altogether precluded. Moreover, there is 

 no projecting lobe at the base of the sickle- shaped dacty- 

 lopodite of the third pair of thoracic legs in my specimen, 

 while such a lobe is clearly indicated in his figure. 



Dana's description of A. scutellata (1852, i, p. 406) is 



