A. K Verrill on Asddians from New England. 291 



nearly covers the surface. The individual zooids are very nu- 

 merous on the upper side, mostly arranged in rather irregular, 

 elongated, elliptical or oi)long systems, composed of many 

 individuals of various sizes. The adult individuals are rather 

 slender and elongated ; the slender post-abdomen equalling or 

 exceeding m length the rest of the body, but not more than half 

 the diameter of the thorax and slightly constricted at base. In 

 young individuals, not half grown, the post-abdomen forms 

 nearly half the whole length, and is very slender. The branchial 

 aperture has six, short, round papillse ; the anal is situated a 

 short distance from the end of the body, and has short incon- 

 spicuous lower lobes, with an elongated, pointed lobe above. 

 The branchial sac is oblong, with numerous longitudinal and 

 transverse vessels and a broad ventral duct The stomach is 

 about as broad as long, subglobular, with the ends truncated 

 and the surface covered with numerous, interrupted, longitudinal, 

 glandular ridges. • The post-abdomen is nearly filled by the 

 large, elongated ovary, which extends nearly to the ])osteri()r 

 end on the dorsal or atrial side, and contains numerous closely 

 packed ovules of comparatively large size, and the cons])icuous 

 male organs, extending through the whole length on the ventral 

 or branchial side, in the form of a slightly convoluted, dark 

 colored duct. The posterior end terminates in a small, obtuse 

 papilla. The atrium, or cloacal cavity, contains eggs in which 

 the embryos are well developed, and in some cases the free, 

 tadpole-shaped larvse. The tunic is speckled with numerous, 

 minute, purplish-brown pigment cells. 



. One of the larger adult individuals measured -30 of an mch 

 in length ; thorax -08 ; abdomen -06 ; post-abdomen "16 ; diameter 

 of thorax -031 to -035; of abdomen about the same; of post- 

 abdomen -015 to -020. 



Amouroucmm stellatum Yerrill, sp. no v. 

 This species forms large, erect, crest-like plates or fronds at- 

 tached at the lower edge to stones and pebbles by short root-like 

 extensions; the outer and upper edges are subacute or rounded, 

 divided into two broad, rounded lobes above. The frond is 

 2-5 mches high, and about the same in breadth, the thickness 

 varying from -20 to -35 of an inch. The tissue is firm and car- 

 Wage-like externally, softer within ; surflice smooth and gla- 

 brous, without adhering sand. The zooids are aiTanged m 

 nearly circular and pretty regular stellate groups, usually con- 

 fining from six to fifteen individuals, arranged around a central 

 sub-circular orifice : in contraction the position of each individ- 

 ual is indicated by an oval spot, more transparent than the 

 common tissue, with a small flake-white spot around the bran- 

 chial orifice. 



