THE 



PHILOSOPHICAL MAGAZINE 

 AND JOURNAL. 



31 st MAY 1824. 



LIU. Descriptions of several new Species of Ascidia. By 

 C. A. Lesueub.* 



Genus ASCIDIA, Lin. 



1. A SCIDIA atra. Body subcylindric, elongated, arquated, 

 -^- sessile; the superior part more slender, terminated 

 by two unequal tubes, slightly separate and parallel ; these 

 tubes have each a terminal opening, which in the shorter tube 

 is closed by five, and in the longer one by six, triangular 

 valves; the substance of the exterior sac is very firm, almost 

 smooth, opaque, and very deep violaceous or blackish. — It 

 occurs attached to rocks, amongst Opuntice, many species of 

 Sertularice, and broken shells. Its position is inclined, being 

 adherent by the side of the base, which is a little more in- 

 flated than the other parts of the body. — -We observed this 

 species at the isles of St. Vincent and Guadaloupe, where, 

 however, it is rather rare. Whilst dredging in the bay of 

 Calicoua, we drew this species from the bottom of the water, 

 with many other objects, amongst which was a beautiful Ho- 

 lothuria, marbled with brown, red, white and blackish, which 

 had the property of dissolving so rapidly as to be observed 

 with difficulty. 



2. A. cavernosa. Body oblong, irregular, terminated by 

 two unequal tubes; that of the branchia and mouth much 

 longer than the other, and directed upwards ; that of the ovi- 

 duct and excretions situated at the base of the first and la- 

 teral ; their apertures are entire, without marginal elevation, 

 or apparent hair, and of a deep colour within ; the exterior en- 

 velope is coriaceous, thick, very firm, opaque, rugous and 

 folded, particularly towards the base, where the folds, united 

 in fasciculi, form three points of attachment, by means of 

 which the animal secures itself firmly to the interior of cavities 

 in rocks and old madrepores ; the colour is that of burnt terra- 



• From the Journal of the Academy of Natural Sciences of Philadelphia, 

 vol. iii. No. 1. for April 1823. 



Vol. 63. No. .'513. May 182*. S s sienna. 



