Hutton. — On Crassatellites trailli. 65 



There is therefore no longer any reason for doubting that 

 this widespread species had established itself in New Zealand 

 even before 1854. It is interesting to note, however, that it 

 does not appear to have spread widely in New Zealand. I 

 have certainly never seen it in the South Island, where I have 

 collected pretty widely for many years past ; and, though I 

 have not personally collected it in the North Island except 

 near Wellington, I have had many terrestrial isopods sent me 

 from different places in that Island, but no Metoponorthus 

 yruinoms till I got those sent by Mr. Hutchinson. 



The same thing is true of another introduced species, 

 Armadillidium vidgare, Latr., which is common in the City of 

 Nelson, but has so far not been recorded from any other part 

 of New Zealand except Mount Egmont, whence a single 

 specimen was sent me years ago by the late Mr. Drew. On 

 the other hand, Porcellio scaber, Latr., another introduced 

 species, is extremely common all over New Zealand, and, in 

 addition to being found near inhabitated places, has penetrated 

 to some extent into the bush far from houses. 



Art. XIV. — On Crassatellites trailli. 

 By Captain F. W. Hutton, F.B.S. 



[Read before the Philosophical Institute of Canterbury, 7th June, 1905.] 



A specimen of this species collected by Professor James Park, 

 F.G.S., and presented by him to the Canterbury Museum, 

 shows a well-marked pallial sinus. It therefore cannot be 

 kept in the genus in which I originally placed it, but appears 

 to belong to Mactropsis of Conrad. It resembles the Mac- 

 tridcB in having a prosogyrous beak, but otherwise it is more 

 like the Mesodesynidce, in which it is usually placed. The fol- 

 lowing is a description of the species. 



Mactropsis trailli. 

 Crassatella trailli, Hutton, Cat. Tertiary Mollusca of New 

 Zealand, 1873, p. 24. 



Shell solid, heavy, closed at both ends, elongato-tri- 

 angular, very inequilateral, produced, flattened and roundly 

 angulate posteriorly. Anterior end rounded ; posterior end 

 obliquely truncated. Both anterior and posterior dorsal 

 margins nearly straight ; ventral margin slightly curved. 

 Umbones slightly prosogyrous. Exterior finely and regularly 

 concentrically ribbed ; the ribs rounded, rather narrower than 

 the grooves, becoming obsolete on the posterior flattened slope 

 of the shell, as well as near the ventral margin. Lunule well 

 marked, lanceolate, smooth. Margins smooth. Adductor scars 

 3— Trans. 



