Mollusca Testacea Marium Britannicorum Author:William Clark Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: transmitted for the nourishment of the body through tubes and variously-shaped walled canals or cavities, though they be neither typical arteries or veins; we go... more » further, and believe that in many of these beings a blood circulation may be as effective through a single walled canal as by a more complex arrangement, and thus receive the necessary aeration, which in most of the lower Invertcbrata is probably cutaneous and effected by endosmose, and that in those animals in which the ambient element can only be admitted into visceral cavities, it is oxygenated by exosmose. ACEPHALA PALLIOBRANCHIATA. TEKEBRATULID;. Having already mentioned most of the incidents of this family, I have only to add, that it consists of three genera, Hypothyris, Terebratula, and Argiope. None of the animals or the shells have occurred on the Devon coasts, except the Argiope dstellula, and that only in a dried state. HYPOTHYRIS, Phillips. H. Psittacea, Chemnitz. H. psittacea, Brit. Moll. ii. p. 346, pi. 57. f. 1, 2, 3. We can only refer to the first vol. p. 150, of the' Zoological Transactions,' for Professor Owen's account of this animal. The shells of this genus are never punctated. A very doubtful British species. TEEEBRATULA, Bruguiere. T. Caput Serpentis, Linnaeus. T. caput serpentis, Brit. Moll. ii. p. 353, pi. 56. f. 1, 2, 3, 4. The valves of this genus are always punctated, and particularly so in this species; it is taken plentifully on the Scotchcoasts. We refer to the second vol. p. 355, of the ' British Mollusca' for a description of this animal. T. Cranium, Miiller. T. cranium, Brit. Moll. ii. p. 357, pi. 57. f. 11 ; and iv. p. 257. This species is said to have occurred in Zetland. The animal has not been observed. ARGIOPE, Deslongchamps. A. Cistellu...« less