NO. 1312. SYNOPSIS OF THE VENERID.^J— BALL. 391 



SAXIDOMUS NUTTALLII Conrad, 1837. 



Baulinas Bay, California, and south to San Diego. 



There are two species of Saxidorn/m on the coast, of which one has 

 brownish niarkings near the beaks in the young, and a trace of purple 

 internally on the upper posterior margin. The other is all white or 

 3^ellowish. The present species is rather thin, but reaches a length of 

 120 mm., and is usually rudely concentrically sulcate. It is the Vemix 

 viaxima Anton, in Philippi, 1846; the Saxidoians aratus Gould, 1861, 

 also called by him in the index S. ovatus (1862); while the young, with 

 its colored markings, he named TajJes gracilis in 1855. Conrad's tyi)e 

 was young, 50 mm. long, but his allusion to the color markings settles 

 the identit}" of the species referred to. 



SAXIDOMUS GIGANTEUS Deshayes, 1839. 



The Aleutian Islands, from Attn eastward to Kadiak, and south- 

 ward to the Ba}" of Monterey, California. 



There is no sufficient evidence of the occurrence of this species on 

 the Asiatic coast. It is solid, broad, and heavy; the young are yel- 

 lowish white; the adult attains a length of 130 mm., and the concen- 

 tric sculpture is much less pronounced than in ^S'. nutUdUi. The 

 exterior is sometimes fulvous, but the interior is always white. Spec- 

 imens which have nestled in rock crevices are usually stunted and 

 distorted. The synonymy has been much confused. It is the Vemis 

 sulcata of Potiez and Michaud, 1844, but not of Montagu, 1803, or 

 Lamarck, 1818. It was named Venerupis gigantea by Deshaj^es, and 

 has been confounded with S. squcdidus Deshayes, a South American 

 species, and N. uuttallii Conrad. 



CYCLINELLA SUBQUADRATA Hanley, 1845. 



St. Elena, West Colombia; Panama Bay; Mazatlan. and northward 

 to Guaymas, on the (xulf of California, in 7 to 25 fathoms. 



Artheniis saccata Gould, 1851; Cyclina saccata Desha N^es, 1853; 

 Artemis tenuis Sowerb}^, December, 1852, not of Recluz, June, 1852 

 (and not Artcuiix tnrgid(( Reeve, 1850), are synonymous. 



CYCLINELLA KROYERI Philippi, 1847. 



Chile and Peru; Salango. West Colombia, in !> fathoms; and the 

 Gulf of California in 14 to 26 fathoms. 



Artt'ijiix niaciJenta. Reeve, 1850, appears to be synonymous. It is 

 Vi'H n.-< I'l'dt/er! Philippi, 1847, but not Zaciaojfs'/s hroyen Poulsen, 1878. 

 It is smaller, more orl)icular, and proportionately flatter than (\ suh- 

 qaadrata. 



