10 JOURNAL OF MARINE ZOOLOGY AND MICROSCOPY. 



(Such cannot, in Jersey , be made out, for the CoraUina region ranges 

 considerably further than half way up the Limpet zone, and is indeed 

 inextricably commingled with it, while Limpets are to be found 

 almost at low water limit, though in small number. 



As useful guides in fixing the vertical distribution of other 

 animals, both these zonings are faulty ; the first because of the 

 frequent absence of fucoid growth in particular localities, and the 

 second because we require a greater splitting up of the space to 

 be mapped. 



For this purpose it is indispensable to choose a group comprising 

 numerous fairly common species, preferably sedentary. 



The Sponges, I find, are too aggregated in the lower half of the 

 littoral, to be serviceable. Thus the highest-living species, Hali- 

 cJwndria panicea, is not met with at all above half-tide mark. It 

 however forms a very well marked zone, extending in solid phalanx 

 to within 5 to 4 feet from extreme low water, the intervening space 

 being what I would term the Pachychalina zone, characterized by 

 the presence of Pachychalina montagui, Isodictya ingalli, and a multi- 

 tude of ascidians — Ciona, Aplidiitm elegans, Morc/iellium, and the 

 Botryllids. 



Below this, and corresponding with the Laminarian zone, comes 

 a region for which, in the zoning of the Sponges, I would propose the 

 term Tetractinellid Zone, signalised by the occurrence there of the 

 massive sponges Pachymatisma, SteUetta collingsi and Dercitus niger. 

 It may be noted, in passing, that one common Tetractinellid sponge, 

 viz., Tethya lyncurium, is sometimes numerous in the Pachychalina 

 zone. 



The Ascidians are still more aggregated at Ioav horizons than 

 the Sponges, while the Hydrozoa and the Polyzoa are often so 

 fastidious and erratic in their choice of habitat, that, to be used as 

 general indices, they are ill suited. I do not, however, wish it to be 

 understood that they are not to be found occupying well-defined zones. 

 Far from this being the case, their dominions have very rigid bounds, 

 capable of exact demarcation. I only mean that, for no apparent 

 reason, they may be absent from their particular zone in one part of 

 the shore, while common at the same height in another ; a tantalising 

 inconstance, if we desire to use them as shore-marks. 



The group, which, after this process of elimination, I found to be 

 the most generally useful in the demarcation of the shore, was that of 

 the Anemones. Here is no massing of species within narrow limits ; 

 the range is well nigh up to high water mark, and progresses by well 

 marked and fairly regular steps to deep water. 



