MR. R. OWEN ON THE ANATOMY OF THE BRACHIOPODA. 157 
arteries to near the hearts, beyond which I could not trace them. I can speak posi- 
tively that there is no longitudinal ganglionic cord on either aspect of the viscera, 
corresponding to the nervous system of the Cirripeds. A single small ganglion is situ- 
ated on the opposite side of the wsophagus, but on a plane posterior to the preceding. 
This, however, I suspect to be the cerebral ganglion, and believe it gives off the nerves 
to the free spiral extremities of the arms, close to the base of which it is situated. 
Some Observations on the Anatomy of Lingula Audebardii, Brod. 
The structure of this species corresponds in all essential particulars with that of Ling. 
anatina as given by Cuvier. The differences appear first in the length of the cilia, 
which in the present species are three or four times longer than those of Ling. ana- 
tina. The subdivisions of the branchial vessels project from the inner surface of the 
mantle, in linear series similar in their direction to those of Ling. anatina: but the 
lines are not continuous; they are composed of distinct and separate folds of the 
mantle, of a minute size, along the convexity of each of which a single vascular loop 
is extended without giving off lateral ramulets, the whole structure affording a beautiful 
example of the first stage in the composition of a complex lamellated gill’. 
All the glandular masses communicating with the alimentary canal bear the green 
‘colour characteristic of the liver, especially that central one surrounding the stomach, 
which Cuvier has marked as the salivary gland in Ling. anatina. Now as the speci- 
mens examined by that great anatomist had been long preserved in spirit, one of them 
having in fact formed part of the collection of Seba, the colour of the parts had pro- 
bably been discharged. Iam therefore inclined to think that Ling. anatina agrees in 
this respect both with the newly added species of the same genus, and with the other 
Brachiopodous genera, and indeed exhibits, in the absence of salivary glands, as of 
dental organs, a correspondence with all the Acephalous Mollusks. With respect to 
Ling. Audebardii, { shall only add, that the distal end of its pedicle is dilated and 
rounded, and in the small specimen dissected did not present any appearance of having 
been attached to a foreign substance. 
General Remarks. 
On comparing together the three genera of Brachiopoda above described, we find 
that although Orbicula in the muscular structure of its arms, and the proportion of the 
shell occupied by its viscera, is intermediate to Lingula and Terebratula, yet that in the 
structure of its respiratory organs, its simple alimentary canal, and its mode of attach- 
ment to foreign bodies, it has a greater affinity to the latter genus. The modifications 
that can be traced in the organization of each of these genera, have an evident re- 
ference to the different situations which they occupy in the watery element. 
Lingula, living more commonly near the surface, and sometimes where it would be 
1 See Fig. 16. 
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