9 
^ le other this is never observed. The young thus adhering 
a re never of the full size of the parent: a circumstance not 
ea sily accounted for; as it seems impossible that they should 
at any time after their first stages of growth, be able to 
loosen their hold and assume a new station. 
The researches of Mr. Thompson have made the history 
°f this class of animals important, by showing their close 
affinity with Crabs and Lobsters. 
* A. ANSERIFERA. Lepas A. Turt. Lin. Mont. Test. 
Brit., vol. 1, p. 16. Stew. Elern., vol. 2, p. 364. Common 
Barnacle. Common on floating wood that has been long 
at sea. Its distinctions from the A. Levis have been 
already pointed out. The stalk, which is from a foot to 
18 inches in length, is capable of voluntary motion, in- • 
eluding contraction and extension; and a point of support 
for lateral bending is afforded by compressing a portion 
of fluid into the requisite limited space. 
A. FASCICULARIS. Lepas F. Mont. Test. Brit., vol. 
2, p. 557. In no volume to which I have access do I find 
a satisfactory description of this species ; it may therefore 
Properly find a place here. Length of the shell, 7 tenths 
of an inch, depth 5^ tenths ; the thickness or inflation con- 
siderable, the cross segment forming an oval posteriorly ; 
texture of the plates thin as tissue paper, and easily broken. 
The dorsal plate is remarkably arched, wide, and ter- 
minating circularly above the stalk. The orifice gaping. 
Anterior lateral plate small, slender, jagged at its point; 
tile larger plate with an everted hinder margin. Colour 
"’hitish, with tints of blue, the soft parts appearing through 
tlte texture. The stalk short, small, fixed in a tumid bed 
°f soft membranous substance ; and the animals project at 
r *glit angles to the substance on which they are fixed ; 
a dhering in clusters, but each standing out in as opposite 
a direction as possible from those with which it is asso- 
rted. 
This is a rare species, since it was but barely known to 
le industrious researches of Montagu. I have met with it 
belied to the stalk of sea weeds ; and once in considerable 
jjdantity, thrown on shore in a storm. It is a stranger cir- 
l ! i tlls tance that I possess some specimens, intermingled with 
e equally rare species, A. Sulcata, and both attached to a 
® a ther of the wing of a gull. 
' S ULCATA. Lepas S. Mont. Test. Brit., vol. 1, p. 17, 
1, fig. 6. Length of the shell 7 tenths of an inch, 
depth 41 tenths. The larger plates are moderately in- 
a ted behind, overlapping at the hinge below ; the anterior 
Plates small ; dorsal plate not running to the point. The 
S1 de plates are thickly covered with raised lines proceeding 
c 
