156 MR. R. OWEN ON THE ANATOMY OF THE BRACHIOPODA. 
species of animal motion of which we find examples in the erectile tissues of higher 
organizations. 
The brachial filaments, when viewed through the lens, presented an equal cylindrical 
figure, and an entire surface ; they are less transparent, and of a more muscular tex- 
ture than those of Ter. Chilensis; they are also thicker and shorter, and more incur- 
vated. Their bases are covered on the inner side of the arms by a small fold of 
membrane’. 
The mouth, a small puckered orifice?, is best seen by dissecting away the transverse 
base of the arms. The wsophagus* passes obliquely through the tendinous wall of the 
viscera, ina direction towards the upper or imperforate valve; having then passed 
between the anterior shell-muscles, it becomes slightly dilated, and surrounded by the 
liver, forming a less capacious stomach than in Terebratula*. The intestine? is con- 
tinued straight to the opposite end of the visceral cavity, and is there again contracted, 
and making a sudden bend upon itself, passes in a slight sigmoid curve to the middle 
of the right side of the visceral belt, which it perforates obliquely, and terminates 
between the lobes of the mantle about half a line below the bend of the arm®, The 
liver’ is of a beautiful green colour ; it is a congeries of elongated follicles closely com- 
pacted together, which communicate by numerous orifices with the stomach. There 
is no gland, analogous to a salivary gland, anterior to the liver ; nor was any gland but 
the liver perceptible in Terebratula; and in this respect they resemble the ordinary 
Bivalves, the mouth being, as in them, destitute of any hard parts for comminuting or 
seizing alimentary substances, and therefore not requiring the superaddition of salivary 
glands. The coats of the stomach and intestines are thick and pulpy, and apparently 
glandular. “ 
Posterior to the liver the whole of the visceral cavity not occupied by the muscles 
and vessels is filled with grey masses of ova. In these masses the distinct granules 
could not be seen; but between the membranes circumscribing the wscera, ova of a 
browner colour could be more distinctly made out. These, I suspect, were on their 
passage to the mantle-lobes, where probably in older specimens they would be seen. 
Poli has beautifully figured the ova of Crania personata, following the course of the 
branchial vessels and obscuring them. He consequently calls these the ovaries, and 
observes that they agreeably ornament the mantle®. 
In Terebratula all my attempts to trace the nervous system were unsatisfactory ; but 
in one of the Orbicule, dissected expressly for that purpose, I succeeded in detecting 
two small ganglia on the side of the wsophagus next the perforated valve, from which 
two filaments accompanying the esophagus through the membranous wall immediately 
diverge and pass exterior to the anterior shell-muscles, accompanying corresponding 
1 Fig. 12. 2 q. Figg. 9. 11. 37, Fig. 11. 4s, Figg. 7. 8. 9.11. 
5 ¢. Figg. 7. 8. 9. 11. 6 u. Figg. 9. 10. 11. 7 v. Figg. 5. 11. 
8 Testacea utriusque Sicilie, vol. ii. pl. xxx. fig. 24. Criopus. 
