4.54. CLASS ECHINODERMATA, 
There is a very fine species of a deep blue, in the Atlantic 
ocean. (Mynias cyanea, Cuv., Rég., An. iv. pl. xv. f. 8.) 
PRIAPULUS, Lam., 
Have a cylindrical body, marked transversely with deep 
annular wrinkles, terminated in front by an elliptical mass, 
slightly wrinkled longitudinally; pierced with the mouth, and 
behind with the anus, from which issues a thick bundle of 
filaments, which may be the organs of generation. ‘The in- 
terior of the mouth is furnished with a great number of very 
sharp corneous teeth, placed like a quincunx, and directed 
backwards; the intestine goes straight from the mouth to the 
anus ; the muscular system resembles that of the holothurie. 
We are acquainted with but a single species from the north 
seas, Holothuria priapus, L. Miill., Zool., Dan. xcvi. 1. two 
or three inches in length, 
LITHODERMIS, Cuv., 
Have the body oval, compressed behind, and the surface is as 
it were incrusted with a stratum of small stony grains, which 
form a very hard crust. The mouth is surrounded with ten- 
tacula, and the intestines appear to have resemblances to those 
of the holothuriz. I do not find any anus. 
We know but a single species from the Indies, Lithod. 
cuneus, Cuv., blackish, two inches in length. 
SIPONCULUS, Gm., 
Have a cylindrical elongated body, with a thick skin, wrinkled 
in both directions; the mouth at an extremity in the form of 
a proboscis, which may be retracted or put forth, by means 
of large interior muscles, and the anus more or less near the 
base of this proboscis. The intestine originates from the 
mouth, proceeds as far as the opposite extremity, and re- 
turns, convoluting spirally round its first part. We find 
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