ANNELIDA. 105 



The Nemerteans, again, are especially abundant between 

 tide-marks, though some range thence to deep water, and a 

 few occur only in the latter. Amphiporus lactijhreus is 

 common under stones, and Lineus gesserensis and Gephaloihrix 

 linearis in still greater numbers, especially in muddy places. 

 The great Lineus marinus is frequently found under stones, and 

 occasionally in the pools. Near low water the Tetrastemnur 

 (such as T. melanocephala, T. Candida, T. vermicula, T.flavida, 

 and occasionally T. dorsalis) occur in varying numbers, the 

 latter, however, attaining its maximum amongst the red sea- 

 weeds in the laminarian region. By splitting the rocks at 

 fissures Nemertes Neesii, Lineus bilineatus, Micrura fasciolata, 

 M. purpurea, and Carinella annulata are found in great, beauty ; 

 while the intricacies in the roots of the tangles afford favourite 

 sites for Nemertes gracilis and others already mentioned. The 

 debris in the fishing-boats is especially productive of fine 

 examples of Amphiporus pulcher and Micrura fusca*, both, 

 besides the ordinary method of progression, swimming grace- 

 fully through the water like freshwater leeches, by throwing 

 themselves on edge and striking right and left alternately 

 with their flattened tails. The curious Nemertes carcinophila 

 is abundant on the ovigerous abdominal hairs of the females of 

 the shore-crab. 



Almost all the Nemerteans live well in confinement ; and 

 while the development of several is known, that of others 

 (such as Nemertes Neesii, N. gracilis, Lineus marinus, L. 

 sanguineus, the Micrura, and Carinella amadata) affords a 

 fine field for further research. The Nemerteans approach the 

 Annelids proper very closely. 



The Rhabdoccela are generally minute, but tolerably numer- 

 ous amongst the red ascidians hanging from cavern-roofs, or 

 algous and zoophytic growths on the under surface of stones, 

 in tidal pools and near low-water mark. 



The Planarians are fairly represented, the common forms 

 frequently occurring under stones between tide-marks, and 



* A fine specimen of the large Cerebratulus angulatus, 0. F. Miiller, 

 was sent me from the neighbouring Bay of Montrose by Dr. Howden ; 

 but unfortunately no proboscis was present. The two forms closely ap- 

 proach each other. , 



P 



