532 Transactions. 
Lepsiella scobina, Nerita melanotragus, Turbo smaragdus, Sypharochiton 
pellisserpentis, Monodonta aethiops, Elminius plicatus, Cellana radians, 
C. ornatus—all species of wide distribution in the intertidal belt through- 
out New Zealand. Where the Ostrea forms a complete covering to the 
rocks only small examples of these animals are found. (Plate 48, fig. 1; 
Plate 46, fig. 2.) 
Modiolus Association. 
St. Clair.—This association occupies the middle portion of the. inter- 
tidal belt. The rocks are large hard lava boulders, and the patches 
é 
shells of Modiolus are found Notoacmea parviconoidea, young Melaraphe 
columbina. Pelecypods associated with Modiolus are a few Mytilus planu- 
Modiolus, Cellana radians, and Monodonta aethiops, but these are reached 
by the wash of every wave. Associated with the Modiolus and Elminius 
are Lepsiella scobina, Sypharochiton pellisserpentis, Risellopsis varia, Mela- 
raphe unifasciata, Cellana ornata, C. radians, and Melaraphe cincta. 
Notoacmea parviconoidea is common on the shells of Modiolus pulex. 
these species except Risellopsis and Melaraphe contained water within their 
shells, and in a specimen each of Cellana and Monodonta was found a 
small amphipod. At one point in the coast-line at Taylor’s Mistake the 
variety rutila is freely mixed with Lepsiella scobina. There is no apparent 
-difference in the habitat to cause a variation of this kind, 
Modiolus confusus Association. 
n brackish water Modiolus confusus takes the place of M. pulex in 
the tidal belt. Unfortunately I have few notes on this association. At 
Spirits Bay a small river runs into the sea, and is for a portion of its 
lower course tidal. Here in the brackish water are a few molluscs. Where 
there is a hard surface Modiolus confusus occurs in clusters. The shells 
are smooth, not at all eroded, and mesure up to 30mm. in length. 
ommon on the botton are two species of gasteropods—Melanopsis tri- 
salleana 
podum. There appears to be a curious mixture on the western shore 
of the Great Lagoon on Chatham Island. Here I gathered Modiolus 
confusus (22 mm.), Antigona stutchburyi (small shells, 25 mm., with convex 
` but not ventricose valves), and Potampyrgus antipodum. 
