1 2 Pratt, Marine Fauna of the Falkland Islands. 



it may be that this species exists in the tropics at great 

 depths, and has thus escaped capture. 



Lepralia. This genus occurs in the north and south 

 temperate zones, and within the tropics ; all the deep-sea 

 forms occur in the temperate regions; the forms living in 

 shallow water occur in the tropics as well as in the tempe- 

 rate regions. This is rather interesting, for it shows that 

 the tropics do not form an insuperable barrier for all 

 species, between the two temperate zones. Then, again, 

 according to Ortmann's view, one would expect to find 

 the deep-sea forms nearer the Equator, if the deep sea 

 affords a passage between the two temperate zones. 



The species L. adpressa occurs north and south of, but 

 not within the tropics, in shallow and moderately-deep 

 water. It occurs fossil in Italian pliocene, Austrian 

 miocene, and tertiary formations at Reggio (Italy). The 

 distribution of this species gives evidence in support of 

 Murray's view. 



Membranipora. The genus is cosmopolitan, chiefly in 

 shallow water, but it also occurs in deep water. 



M. albida, Tongatabu (Pacific), 2i^S., 18-20 fath. 

 Bermuda, 38^37'N., 450 fath. Singapore. 



M. crassimarginata, Bass Strait, 38-85 fath. Heard 

 Island, 75 fath. Tristan D'Acunha, no- 150 fath. 

 Gulf of Florida, 13-60 fath. 



M. multifida, Cape of Good Hope, 450 fath. Chal- 

 lenger station 320, 37*^ 17'S., 600 fath., green mud. 



It is notable that the species occurring at great depths, 

 are found only in temperate regions. The tropical forms 

 occur m fairly shallow water. 



Membranipora menibranacea occurs in north and 

 south temperate zones, but not within the tropics. 



Micropora. Genus extends back at least to the chalk 

 period. It occurs in north and south temperate zones, 



