Invertebrata. Zoological Collections, 245 



TaUtrus or the Orchestes, as well as the Terehella and Arenicola ; and in 

 muddy places, the Nephthys, or little Sipunculi. 



The third zone is principally characterized by the presence of corallines, 

 and is only bare at very low tides. The animals which inhabit it differ 

 according to the nature of the locality ; on the rocks not oveiturned, but 

 beaten by the waves, we often see mussels, limpets, &c. ; in the most 

 sheltered places the green Actinice and compound Ascidice fix themselves ; 

 where many large stones occur loose in the soil, we find, on turning them 

 over, the PorceUana, Doris, Pleurohranchus, Haliotis, simple and compound 

 Ascidioc, Poll/noes, Serpulce, Planaria, &c. ; and when the rocks are irregu- 

 larly lying upon each other, their interstices are often clothed with sponges, 

 TethicB, Lobularicc, and Ascidia. The portions of this region, which are not 

 rocky, are also frequented by a great number of animals, which are never 

 found at higher levels. If the sand be covered with Zostera marina, we are 

 almost sure to find in the pools left during ebb tide, millions of little Ceri- 

 thia, a.nd many i?mo« ; and, lastly, in places where the sand is not mixed 

 -much with mud, we olten find, some incilies below the surface, the Cardiunif 

 Venus, and Solen, as well as the Terebella and other Annelides. 



In the fourth zone, which is only uncovered at the lowest tides, the rocks 

 are covered with Laminarice, and dilTerent large marine plants, amongst 

 which are found beautiful limpets, {Patella pellucida, Lam.) Asterias, ActinicE, 

 and many animals which are also found in the preceding zone. In this 

 region alone, MM. Audouin and Milne Edwards found the CaUianassa, 

 Axius, and Thia, which lie buried in the fine, clear sand. 



Lastly, at a still lower level, that is to say, where the sea never retires, 

 the region commences, which is inhabited by the Osirea, Cahiptrcea, Pecten, 

 ■ Aphrodita, certain Poituni, the Maia, the large species oi Asterias, &c Ibid. 



Ciliary or Vascular Motions in the Arenicola Piscatorum, (Lumbricus 

 Mariims, Lin.) — Our readers will recollect to have read with interest, in a 

 former Number of tliis Journal, (Vol. II. p. 334,) a paper by Dr Sharpey 

 on the mechanism by which respiratory currents are produced in certain 

 aquatic animals. These currents were shewn to take place along surfaces 

 which are beset with innumerable vibratile cilite, in constant motion ; and 

 were noticed as occurring, amongst the Inverlebraia, in the common mussel, 

 the fresh water mussel, the oyster, and another species of bivalve unnamed; 

 the Doris and Eolis of the Nudibranchiala ; the Buccinum. undatum, and other 

 species of the Pectinibrancldata ; and the Patella and Oscabrion, {Chiton, 

 Lin.) which form the tvro genera of the Cy clobr and data ; in the Actinia of 

 the Radiata ,- and the Amphiirite of the Annelides. 



During an anatomical examination of the sand-worm {Arenicola piscatorum) 

 belonging to the family Dorsalice, (v/ith dorsal branchiae,) we have detected 

 an apparently analogous motion to that of the respiratory ciUTents of 

 Dr Sharpey, in connection with those internal organs supposed by Sir E. 

 Home to be livas. The branchiae in this animal are remarkably well 

 developed, and composed of thirteen expansible tufts, placed along each side 

 of the back ; but we have not been so fortunate as to observe any ciliary 

 or other motions along the surface of these organs, — which would indeed 

 seem to be rendered superfluous, by the great facility of motion with which 

 they are, as a whole, endowed.* 



* This remark may be also applied to other species of Annelides which have fallen uuder 

 our examination, and particuhirly to the Amplatrite ventilabrum and Terebella concJiilega of 

 the second division of AinpliUfttcea', with terminal fan shaped, or ramose branchiae placed 

 at the anterior extremity of the body, — a disposition which has been usually held to be 

 common to the AuiphitriUetE, and wliich is apparently rendered necessary by their 

 inhabiting- tubes imperforate at the sides. Dr Sharpey, however, states, that the annelide 

 he examined, and which he informs us Avas the Amphitrite a ruche of Cuvier, (Sabellaria 

 aiveolata. Lam. of the first division of AmpMtritoBce ,) had rfwrsa^ branchiae ; in which case 

 the description of both Cuvier and Lamarck will require re-exaraination. I'he Sabeliaria 



