_Primordial valves_ very plain, with the usual hexagonal structure: those of the terga, rounded at both ends, instead of being square, as in the mature calcified valves. _Peduncle_ short, narrow, not half as long as the capitulum; paved with minute equal beads, as in the genus Dichelaspis. _Mouth._--Mandibles with the fourth tooth very small; inferior angle rudimentary. Maxillæ, with three great upper spines, beneath which there is a deep notch bearing some delicate spines; inferior upraised part, as in _P. Kæmpferi_. _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. Kæmpferi_, and is evidently a representative 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 obliqueness 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 maxillæ; 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 Pæcilasma, 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. 3. PÆCILASMA CRASSA. Pl. II. Fig. 3. ANATIFA CRASSA. _J. E. Gray._ Proc. Zoolog. Soc., 1848, p. 44, Annulosa, Tab. iii, figs. 5, 6. _P. valvis 5; carinæ termino basali in discum parvum infossum producto: scutis convexis, dentibus internis umbonalibus nullis: tergis pæne rudimentalibus, vix carinâ latioribus._ Valves 5; carina with the basal end produced into a small imbedded disc; scuta convex, without internal umbonal teeth; terga almost rudimentary, scarcely broader than the carina. Spines on the segments of the posterior cirri arranged in single transverse rows. Madeira; attached to the _Homola Cuvierii_, Rev. R. T. Lowe. British Museum.[31] _General Appearance._--Capitulum highly bullate, or thick. Valves rather thick, opaque, either pale or dark flesh-red, smooth, yet rather plainly striated from the umbones. There are a few very minute spines on the membranous borders of the valves.