128 DICHELASPIS L0WE1. 



small teeth, as in B. Grayii. Notwithstanding these 

 differences, I should not be much surprised if the present 

 form were to turn out to be a mere variety. 



4. Dichelaspis Lowei. PL II, fig. 8. 



D. scutorum segmento basali angustiore quam occlu- 

 ders segmentum, longitudine fere f : tergorum parte in- 

 feriori duplo latiore quam occludens scutorum segmentum. 



Scuta with the basal segment narrower than the occlu- 

 dent segment, and about four-fifths as long as it. Terga 

 with the lower part twice as wide as the occludent seg- 

 ment of the scuta. 



Mandibles with four teeth ; segments of the three pos- 

 terior cirri with eight pair of main spines. 



Hab. — Madeira; attached to a rare Brachyourous Crab, discovered by 

 the Rev R. T. Lowe. Yery rare. 



General Appearance. — Capitulum much compressed, 

 sub -triangular, formed of very thin membrane ; valves im- 

 perfectly calcined, and thin. 



Scuta formed of two narrow plates placed at about an 

 angle of 50° to each other, and united at the umbo by a 

 non-calcified flexible portion. The primordial valve is 

 situated at this point, but chiefly on the occlnclent seg- 

 ment. The occludent segment is about twice as wide 

 and about one fifth longer than the basal segment, which 

 latter is rather sharply pointed at its end. The occludent 

 segment is slightly arched, a little narrowed in on the 

 occludent margin close to the umbo ; its upper end is 

 broad and blunt ; it runs throughout close to the edge of 

 the orifice of the sack, and its longer axis is in the same 

 line with that of the terga. Close to the umbones, on 

 the under side of the basal segment, there is, on each 

 valve, a longitudinal calcified fold, serving as a tooth. 



