106 P.ECILASMA AURANTIA. 



Carina, almost of equal narrowness throughout, barely 

 concave within ; lower end triangular, abruptly truncated, 

 and not crested. 



Primordial valves very plain, with the usual hexagonal 

 structure : those of the terga, rounded at both ends, in- 

 stead of being square, as in the mature calcified valves. 



Peduncle short, narrow, not half as long as the capi- 

 tulum ; paved with minute equal beads, as in the genus 

 Dichelaspis. 



Mouth. — Mandibles with the fourth tooth very small ; 

 inferior angle rudimentary. Maxillae, with three great 

 upper spines, beneath which there is a deep notch bear- 

 ing some delicate spines ; inferior upraised part, as in 

 P. Kcempferi. 



Cirri. — Rami of first cirrus hardly more than one 

 third as long as the rami of the second cirrus, which 

 latter rami are unequal in length by only two segments ; 

 the posterior ramus being the longer one. 



Caudal Appendages, with only two or three lateral 

 bristles, besides those on the summit. 



Size. — Capitulum, three to four tenths of an inch long. 



General Remarks. — This species has the closest general 

 resemblance to P. Kcempferi, and is evidently a repre- 

 sentative of it. On close examination, however, almost 

 every part differs slightly ; the chief points being the 

 narrowness of the basal margin of the scuta ; the oblique- 

 ness of the truncated basal end of the terga and the 

 sharpness of the upper end ; the rudimentary state of 

 the inferior angle of the mandibles ; the character of 

 the spines on the maxillae \ the proportional lengths of 

 the cirri, and the fewness of the spines on the outer 

 sides of the caudal appendages. The fact of Madeira 

 having this Paecilasma, a representative both in structure 

 and habits of a Japan species, is interesting, inasmuch, 

 as I am informed by Mr. Lowe, that some of the Madeira 

 fishes are analogues of those of Japan. 



