POIRETIA. 165 



Type, P. algira (Brug.). Distribution, Algeria, Sicily, 

 Italy, Dalmatian coast, Greece ; Tertiary of Europe. 



Poiretia has a shell like Euglandina, but the development 

 of a blind sack on the penis allies it rather to L&voleacina. 

 From both genera Poiretia differs by its short labial lobes 

 which have been figured by Bourguignat (Malac. de 1'Algerie). 



The varying forms of Poiretia have been discussed at some 

 length by von Martens (Malak. Blatter, vi, 1859, pp. 154- 

 164), by Bourguignat (Malacologie de 1'Algerie, ii, p. 117, 

 1864), and by Kobelt (Iconographie Europaischen Schaltrag- 

 enden Conchylien, v, p. 55 (1877), and neue Folge, iii, 1888, 



P.I. 



The decision of von Martens and Kobelt that all recent 

 forms of Poiretia are varieties of a single species seems to me 

 to be open to appeal, for the reason that none of the authors 

 who have written on the genus have taken into account the 

 sculpture of the embryonic shell, but based their conclusions 

 upon the general shape of the adult, and the shape of the 

 columella. 



1. P. ALGIRA (Bruguiere). PI. 31, figs. 2, 4. 



The type of Bulimus algirus was collected by the Abbe 

 Poire t at Algiers. It measured 16 to 17 lines long by six 

 wide about 32 to 34 by 12 mm. This indicates the rather 

 slender form of northern Africa, Sicily and southern Italy 

 as the typical algira. In this form the first % whorl, or 

 nearly that, is quite smooth, elevated and convex; then fine, 

 regular, slightly 'arcuate rib-striae begin, very weak at first; 

 but soon becoming stronger; they weaken near the lower 

 suture; this sculpture continues to the middle of the third 

 whorl (the embryonic shell being composed of 2^2 whorls), 

 where it gives place to the more irregular sculpture of the 

 neanic stage. A narrow but distinct ridge borders the suture 

 of the embryonic whorls, running upward nearly to the apical 

 end of the suture ; below this ridge the whorl is slightly con- 

 cave. PL 31, fig. 2, represents the apex of a specimen from 

 Paestum, Italy. The columella is usually more concave than 

 in var. cornea. Fig. 4, copied from Kobelt, represents a 

 Sicilian shell. 



