888 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



PITARIA UNICOLOR Sowerby, 1835. 



Humboldt Bay, Lower California, and south to Panama, 

 Somewhat compressed, the concentric sculpture obsolete in the 



middle of the disk, the color uniform white or brownish. The brown 



variety is Cliione had la Gray, 1838, and Oytherea Kguhi Anton, 1839. 



Cytherea luhrica Sowerby, 1835, is perhaps identical. Some specimens 



are almost rostrate. 



PITARIA VULNERATA Broderip, 1835. 



Magdalena Bay, on the P^icitic shore of Lower California, to the 

 Gulf of California and south to the Bay of Panama. 



Remarkable in its violet zones of coloration and for havino- the 

 inner margins often obscureh" crenulate, a feature not known else- 

 where in the genus. It is the CytJierea tricolor of Pease (MS.) accord- 

 ing to Romer, 1867. The young are maculated with brown and the 

 adults sometimes radially lineate with the same color; young speci- 

 mens of elongate ovate form, which have not assumed the violet rim, 

 have a very different aspect from the mature shell or the normally 

 orbicular young ones. 



PITARIA (HYSTEROCONCHA) LUPANARIA Lesson, 1832. 



Ballenas Bay, Pacilic coast of Lower California, the Gulf of Cali- 

 fornia, and southward to Payta, Peru. 



A larger l)ut less elegant analogue of the Antillean P. dione Linnaeus, 

 easily recognizable by the violet spots at the base of the spines. It 

 appears, as from China, under the name of Cytherea mniUameTlosa 

 Gaudichaud, in the Recueil des Coquilles non ligurees of Delessert in 

 1841. It has also been regarded by several authors as a mere variety 

 of P. dione. Dione exspinata Reeve, 186§, is a mutation in which the 

 spines are abortive. Northern specimens usually have the concentric 

 sculpture carried evenly across the disk, but in the south a variety is 

 common in which the ribs are obsolete on the posterior half of the disk. 

 The name is frequently misspelled Ivpinaria. It is Oytherea dronea 

 Gray, 1833. 



PITARIA (LUPANARIA var.) MULTISPINOSA Sowerby, 1851. 



Realejo, Central America, and southward to Payta, Peru. 



This is a small form in which the concentric sculpture and spines are 

 sharp and crowded, while the coloration is less intense, so that the 

 whole shell is more like P. dione than the better developed normal 

 form is. There seems to be insufficient reason for regarding it as a 

 distinct species. The Cytherea Irevispinosa Sowerby, 1851, seems to 

 have been founded on a single bleached specimen in which the inner 



