Isidora.] GASTKOPUDA. 615 



not shining. Spire elevated conic, its height about two-thirds that of 

 the aperture. Protoconch minute, pointed. Whorls 5, usually broadly 

 shouldered, the shoulder sloping, but sometimes convex ; body-whorl 

 large, somewhat inflated, rounded at the periphery ; base narrowed. 

 Suture not much impressed. Aperture oblique, ovate, angled above. 

 Outer lip convex, thin and sharp. Basal lip narrowly arched and 

 slightly effuse. ColumeUa oblique, twisted, slightly arcuate. Inner 

 lip thin, reflexed over the columella and closing the umbilicus, spread- 

 ing over the flattish parietal wall. 



Diameter, llmm.; height, 17mm.: aperture, 5mm. by 10 mm. 

 Proportion of diameter to height, 1:1-4 to 1 : 1-8. Proportion of 

 diameter t height of aperture, 1 : 1-9 to 1 : 2-3. Diameter of height 

 of aperture to height of shell, 1 : 14 to 1 : 1-7. 



Type in the British Museum. 



Hob. Lake Takapuna ; Wanganui ; Parua Bay, Whangarei ; 

 Waikato River, near Huntly ; Chatham Islands ; Coromandel coast 

 (Hochstetter). 



Farn. ANCYLID^I, Menke. 



Animal not spirally coiled ; tentacles short and compressed ; in- 

 ferior pallial lobe transformed into a branchia. 

 Shell non-spiral, conical, limpet-like. 



KEY TO GENERA. 



A. Shell with an internal posterior horizontal lamina, free and 



projecting on the right side ; present in the young shell . . LATIA. 



B. Shell with an internal septum, partly closing the upper part of 



the shell ; absent in the young shell . . . . . . GUNDLACHIA. 



Genus 1. LATIA, Gray, 1850. 



Latia, Gray, P.Z.S., 1849 (1850), 168. Type : L. neritoides, Gray. Pdex, 

 Gould, 1852. 



Animal with the eyes at the outer bases of the tentacles ; foot 

 elongated oval ; a pulmonary cavity, its opening on the right side ; 

 visceral commissure long. There is no jaw. Central tooth of radula 

 bicuspidate, laterals unicuspidate, marginals tricuspidate. 



Shell ancyliform, with the apex marginal, and situated at the 

 left posterior side, incurved, small ; aperture very large, oval ; margin 

 thin and sharp ; posteriorly with a narrow, thin, concave lamina, 

 its right edge bent down and free, forming a thin and sharp-edged 

 vertical lamella. 



Distribution. New Zealand only. 



In the Index F.N.Z. Hutton says (p. 9) that Latia is found fossil 

 in North America. Dr. W. H. Dall kindly supplied the following 

 information : " We have a Lafo'a-like species of shell living in Alabama 

 which Pilsbry has named Amphigyra. It is probable that our fossil 

 Latia is a precursor of this, and not a true Latia at all." 



