256 TESTACEOUS MOLLUSCA. 



like scales ; dorsal edge straight, anterior rather sloping, ventral 

 somewhat rounded ; anterior angles rounded : vertex somewhat 

 hooked. 6... 8. Panama. 



P. Zelanica. Gray in Yates N. Zealand. — Gray Die/. Zeal. 

 Triangular, elongated, blackish, convex, with rather close radiating 

 ribs armed with close short semicylindrical hollow spines, within 

 purplish, pearly. New Zealand. Differs from Squamosa in being 

 smaller, black, and having the anterior base more truncated. New 

 Zealand. 



P. Lanceolata. Sow. Z. P. 1835. Lanceolate, towards the dor- 

 sal edge with radiating longitudinal riblets, almost unarmed towards 

 the posterior ventral margin, riblets distant, muricated, with dis- 

 tant rather long subrecurved scales ; dorsal edge straight, anterior 

 rather straight and somewhat sloping, ventral subventricose. 3J 

 . . 7f . Puerto Portrero. 



P. Inflata. Chem. 8. p. 215. f. 771.— W. t. 12. /. 5.—D.p. 

 Very tumid, uniform olivaceous horn-coloured, moderately elonga- 

 ted, triangular satchel-shaped, with radiating unarmed ribs which 

 do not extend to the anterior base or the wide posterior ventral area 

 which is covered by subreticulated wrinkles and defined by an ob- 

 solete longitudinal keel : hinge margin somewhat shorter than the 

 posterior ventral, the former nearly straight and armed at its edge 

 with small prickles, the latter incurved near the beaks and convex 

 as it approaches the anterior base, which is arcuated and subangu- 

 lated at each extremity. 6. Nicobar hies, 



P. Rugosa. Sow. Z. P. 1835. Large, rough, triangular, with 

 obtuse radiating ribs, anteriorly broad and rounded ; ribs anteriorly 

 armed with large elongated irregular somewhat recurved foliaceous 

 tubular scales : dorsal edge straight ; posterior ventral somewhat 

 contracted. 6.. 9. Panama. l 



TRIBE MALLEACEA. 



Foliaceous, more or less inequivalve ; having the ligament marginal, 

 somewhat linear, and either simple or interrupted by the crenulations. 



CRENATULA. 



Subequ'walve, flattened, somewhat distorted and lamellar ; no special 

 opening for the byssus; hinge lateral, linear, margined and crcnated ; 

 the crenulations in a regular series, callous, and somewhat hollowed, 

 receiving the ligament. 



1 See too the P. Virgata, andDELTODEs, of Menke's Specimen 

 N. Hollandioe Molluscorum. 



