part 3] THE TEIAS OF jS'EW ZEALAND. 195' 



remarks that it approaches very closely to Fseudomonotis ocliotica 

 var. sparsicostata. I have a mass of felspathic sandstone from 

 Kichmond, with a specimen on it which seems to agree with Freeh's 

 variety. It certainly resembles the variety of Ps. ochotica, but it 

 seems to me to be merely a more full^^-groAvn example of Ps. 

 riclimondimia, in which the ribs have become nodose tow^ards the 

 margins, where they are interrupted by coarse growth-lines. It 

 retains, however, the characteristic rounded outline of this species : 

 it measures 81 mm. in length and 65 mm. in height. 



The more common form, however, is smaller. The Geological 

 Survey possesses a very fine specimen with the two valves together, 

 which is illustrated (tigs. 9« & 9&). It is 45 mm. long, 87 mm. 

 high, and 11 mm. thick, and comes from the eastern slopes of 

 Mount Heslington, near Garden Gully. 



Localit}^ and horizon. — Richmond, and the eastern slope of 

 Garden Gully in the Nelson district ; also in the Hokonui Hills. 

 It is wanting in the coast-section at Nugget Point. It occurs in 

 enormous quantities in more or less decomposed felspathic sand- 

 stone, and marks a Noric horizon apparently below that of 

 Ps. ocliotica. In onh^ one case did I see any other fossil associated 

 with it, Avhereas I found several gasteropods and brachiopods in 

 the Pseudomonotis-ochotica Bed in Garden Gully. It is recorded 

 from New Caledonia. 



MoxoTTS SALi^s'AEiA Broun. (PI. XIX, fig. 10, & PL XX, figs. l-3.> 



1830. Leonliard & Broun, .Jahrb. f. Min. &c5p. 284 & pi. iv, fig. 1. 



1907. J. Wanner, ' Triaspetrefakten der Molukken ' p. 190 & pi. ix, figs. £-4. 



Among the Monotis-YiVe shells that occur at Okuku the right 

 valves are nearly as convex as the left, whereas in most specimens 

 of Pseudomonofis in New Zealand the right valve is nearly fiat or 

 even slightly concave. Also, as alread}^ stated, no trace can be 

 seen of the anterior byssal notch and ear which occur in the right 

 valve of Pseudomonotis. 



For some unapparent reason the shells in this limestone-bed tend 

 to vary in a manner analogous, though to a less extreme degree, 

 to the variation in those of Pseudoinoiiotis ocliotica. The word 

 ' varietv,' therefore, is to be understood in the same sense as that 

 in which I have used it in discussing the last-named species. 



The variation tends to produce a reduction in size from the large 

 flat form which ma^^ be regarded as the normal form, accompanied 

 by a progressively strong arching of the valves, especially of the- 

 left valve, without, however, any increase in the size of the ribs. 



MONOTIS SALTNARIA. (PI. XIX, fig. 10.) 



The largest specimen that I examined is a left valve 70 mm. 

 long and 57 mm. high. It has twenty very regular, equidistant, 

 straight, or slightly-curved primary ribs, which radiate from the 

 beak ; between these occasional fainter secondary ribs n])pear at 



