NO. 2331. WEi^T AMERICAN M0LLUSKS—BART8CH. 163 



Tablet 1716 contains three sp. richly colored, of which two retain their 

 opercula. — 1717, 3 sp. pale nonbanded variety, one with beautiful incrustation 

 of Coralline. 



I fear that the specimens with the red opercula to which he refers 

 are Barleeias^ probably Barleeia alderi Carpenter, which he describes 

 as Jeffreysia alderi on the same page on which the present form is 

 diagnosed, for that form resembles the present species quite a bit, 

 but has a thimble-pitted nucleus and a different operculum. 

 Genus SYNCERA Gray. 

 1821. Syncera Gray, JNied. Kepos. London, vol. 15. p. 239. 

 1830. Assiminea Jeffbeys, Trans. Linn. Soc, vol. 16, p. 378. 



Shell conic, usually strong. Nuclear whorl smooth, the rest of the 

 shell marked by lines of growth and fine spiral striations only. Outer 

 lip simple; inner lip continuing over the base as a thick parietal 

 callus. Operculum subspiral, thin, horny. Animal with the muzzle 

 deeply notched in front; tentacles two, short, cylindric or club 

 shaped, contractile, bearing the eyes at their tip ; respiratory orifice 

 on the right side. 



Type, /Syncera hepatica Gray [=Assiminea grayana Leach] Srjn- 

 ceras are littoral forms, frequently inhabiting the brackish reaches 

 of our coast. 



Four species of the genus Syncera are known from the West Coast 

 of America at the present time. Two of these, Syncera translucens 

 Carpenter and Syncera compacta Carpenter, were named by Dr. 

 Philip P. Carpenter in his supplementary report on the present state 

 of our knowledge with regard to the mollusks of the West Coast of 

 of North America, published in the Report of the British Associa- 

 tion for the Advancement of Science for 1863. In the same paper 

 he also published Assinmiea suhrotundata Carpenter and ? Paludi- 

 nella castmiea Carpenter. Of the latter he states that it " may be an 

 aberrant Assiminea^ These two have since been transferred to the 

 section of Algamorda of the genus Littorina by Dr. W. H. Dall. 



In 1865 Try on bestowed the name Hydrohia calif arnica Tryon 

 upon the shell previously designated as Jeffreysia translucens by 

 Carpenter. It is not strange that Tryon did not recognize this fact, 

 for Carpenter's diagnosis was so terse that it is scarcely recognizable. 



The present paper adds two new members to the genus from the 

 West Coast, one from Lower California and the other from Panama. 



KEY TO THE WEST .\MER1CAN SYNCERAS. 



Altitude of adult shell more than 6 mm panamensis. 



Altitude of adult shell less than 3 mm. 



Shell elongate-ovate magdalenensis. 



Shell not elongate-ovate 



Shell broadly ovate translucens. 



Shell not broadly ovate 



Shell globular compacta. 



