[ 449 ] 
XVII. Description of a new Species of Annelide belonging to the Family Amphinomide. 
By W. BAIRD, M.D., F.L.S. 
(Plate XLV.) 
Read January 21st, 1864. 
AMPHINOME DIDYMOBRANCHIATA. 
CHAR. A. caruncula grossa, lobata, rubra; setis pedum numerosissimis, longissimis, 
albis; branchiis in fasciculis duobus, arbusculiformibus, rubris. 
The genus Amphinome, first established by Bruguière, and afterwards more strictly 
defined by Blainville, contains some elegant and curious species of worms. The number 
now known and described is considerable, but none have as yet been discovered natives 
of the British seas. They are chiefly found in hot climates, and many of them are 
adorned with brilliant colours. The species which I have now to describe is, however, 
perhaps the most beautiful of all. In length it is about 5 or 6 inches, and, including the 
setze on the feet, fully 1} inch in breadth. The dorsal surface of the body in some 
specimens is of a light olive-green, in others a light greenish brown; the ventral surface 
is of a light yellow colour, the caruncle and branchie of a bright carmine, and the long 
setze of the feet pure white. It is somewhat narrower at the anterior, and considerably 
50 at the posterior extremity. The number of segments into which the body is divided 
is about eighty-four; the first four or five are very small, and the last eight or ten 
equally so. The surface of the back is irregularly striated across, and marked with 
numerous flat granulations. The segments of the body are rather narrow and separated 
from each other by a fine, nearly black line. The proboscis (Pl. XLV. fig. 2 a, fig. 3) 
When protruded is very large, terminating in a circular thick fleshy pad, the surface of 
Which is sculptured with circular waved grooved lines. The antenne are all short, but 
the median is longer than the others; they are smooth, not articulated, and of a white 
colour. The eyes are very distinct; two pairs; the anterior larger than the posterior. 
The caruncle (fig. 1 a, fig. 4) is large and fleshy, covering nearly five of the first seg- 
ments; it is composed of a number of small lobes, and is of a fine carmine hue. The 
branchise (fg. 15, fig. 5) exist on all the feet, small on the anterior segments, but 
becoming gradually larger as they descend, and at about the third part of the length of 
the body, and from that to tlie posterior extremity, are of a moderate size. They consist 
Of two separate branches (fig. 5 a, b), not arising from the same stem, but at a short 
distance from each other—a disposition of these organs which none of the described 
Species exhibit, and which might almost be sufficient to constitute asubgenus. They 
differ in size, the one nearest the base of the foot (fig. 5 a) being only half the size of the 
ther; but both are arbuscular in form, and are composed of three branches, each branch 
Consisting of several twigs, and each twig being divided into two or three branchlets. 
