90 Dr. A. Philippi's Zoological Notices. 



ventral margin, but with the anterior margin ; so that the point 

 of commencement of the shell is situated at its hinder end, 

 and not at the vertex ( Wirbeln), as in other Conchylia. It 

 appears that a great portion of the dorsal margin is subse- 

 quently re-absorbed. The vertices thence appear in part un- 

 cinate. The left adhering shell is exceedingly thin, other- 

 wise similar to the other. The two shells inwardly, as well 

 as the tube, are of a nacreous lustre; thus rendering it 

 extremely difficult to distinguish mantle and muscular im- 

 pressions. A hinge is entirely wanting, and there is even no 

 peculiar cartilaginous ligament ; I merely find a weak fibrous 

 corneous ligament. (Fig. 4 b.) Where the two shells touch 

 one another at the back there is frequently a projection in the 

 tube, and we in general meet with an oblique projection 

 (Vorsprung) where the space for the shell ceases and the true 

 tube commences. The spinoid tubes are present ; they are ir- 

 regular, and are only employed by the animal where it finds 

 a free space in the Balanus mass. They are in general lost 

 on loosening the house, so that rarely any other trace remains 

 of them than the point-like apertures in the interior of the 

 shell, as I have represented in fig. 2 e. In some successful 

 cases, however, they are seen very distinctly. 



The animal has exactly the form of a sack, which in front 

 has but a very small fissure, out of which the apex of the very 

 thin foot can scarcely exsert itself. (Fig. 1. and 4.) Poste- 

 riorly the mantle is prolonged into two siphons, cohering nearly 

 to the apex, which reach to the extremity of the tube. The 

 common portion of the siphons terminates with a fringed 

 border, and then follow two very short tubes, of which the 

 inferior or branchial siphon is broadest. Both are provided 

 at their aperture with simple cirrhi, and are carmine red, 

 while the remainder of the animal is colourless. It has, 

 moreover, to be observed, that the common tube before its 

 border is covered with a quantity of grains of sand, which 

 are not easily separable from it. (See Fig. 3.) Fig. 4. ex- 

 hibits the animal, after having been some time in spirits, 

 lying on the right shell. The two adductores, of which the 

 posterior one is round and large, the anterior one kidney- 

 shaped and small, are at present very distinct. If the mantle 

 is cut open in the ventral line, it is first observed that the 

 mantle in the ventral side is very thick and fleshy ; poste- 

 riorly the strong muscles which draw back the siphons are in 

 view ; in the centre, the semicircular branchiae, out of which 

 the small narrow vermiform foot {d in fig. 5. and 6.) projects ; 

 and above this, on each side, two very long, linear, somewhat 

 curved appendices buccales, c. On each side there is only one 



