:^32 



Superior surface of the head ornamented Tvith an imper- 

 fectly sculptured " fleur-de-lis posterior portion obtuse- 

 ly elevated, producing a marginal rim. Eyes small, reni- 

 forra, indigo blue, and placed near the lateral and ante- 

 rior portion of the head, so deeply impressed in the mar- 

 gin of the shell as to be easily distinguished from beneath. 

 Inferior pair of antenncB longer tlian the superior, corres- 

 ponding in length to the width of the head, transversely, 

 from spine to spine; articulations four in number; last 

 segment longest, the remaining three gradually diminish- 

 ing in length as they proceed to the place of insertion ; 

 segments triangulate, with angular projections on their 

 surfaces ; edges of the angles, and articulating extremities 

 rigidly spined. Terminating filament about the length of 

 tlie basal articulations, gradually attenuated until it di- 

 minishes to a finely pointed apex. Superior antenna half 

 the length of the inferior, three-jointed, and terminating 

 with an attenuated filament whose articulations are indis- 

 tinct ; segments angular, external one much the longest ; 

 extremities and angles likewise spined. Mouth with the 

 labrum or upper lip hard and massive, resembling in 

 form a reversed heart. The mandibles are without palpi, 

 stout and osseous, tipped with a hard and black enamel. 

 The maxillae are furnished with the usual palpi. The 

 lower lip, or superior foot-jaws when united, sub-cordate; 

 its palpi five-jointed, snugly embracing the manducatory 

 organs along their base, like a row of ciliated leaflets. 



The thorax is composed of seven distinct segments, each 

 one being beautifully ornamented on its superior surface 

 by an elongated and sub-conic insculptation, forming a 

 series, whose pointed apices almost unite along the longi- 

 tudinal dorsal ridge. These segments are finely bordered 

 along their posterior articulating edges by an elevated and 

 continuous marginal rim, extending to the lateral extre- 

 mities of the shell. The cephalic depression is likewise 

 margined by an obtusely elevated border. Each segment 



