254 AMERICAN JOURNAL 



the kindness of Mr. R. E. C. Stearns, came too late to be figured, 

 but the radula, as I suspected, is that of a typical ColUsella. 

 The uncinus is straight, slender and exceedingly small. The 

 animal appears to have been pellucid, with a black spot on the 

 front of the head. The tentacles are rather short, the eyes very 

 black and large, and the mantle edge smooth. The whole crea- 

 ture is extremely compressed laterally, from its habitat. 

 Collected at Monterey, Santa Barbara and San Diego. 



COLLISELLA (?) DEPICTA, Hinds. 



Patelloida depicta, Hinds, An. N. Hist, x, 1842, p. 82, pi. vi, 

 fig. 4. 



This species and the last are certainly very different from the 

 true Nacellce^ and should not be referred to that genus. They 

 owe their elongated and compressed form to their restricted hab- 

 itat (on a Zostera-frond), but, unlike (7. alveus, cannot be referred 

 to any species now known, of the usual oval form. It is proba- 

 ble that this species also will be found to belong to this genus. 

 It is quite likely that thorough dredging would result in procur- 

 ing non-compressed specimens, which might have grown on peb- 

 bles, &c.. as in the case of C. testudinalis, var. alveus (Couth.), 

 which I obtained of all forms at Sitka, and also the next species. 

 Habitat from Santa Barbara to San Diego. 



COLLISELLA (?) TRIANGULARIS, Cpr. 



Nacella {? paleacea var.) triangularis, Cpr., Proc. Cal. Ac. Sci. 

 iii, p. 213, 1866. 



Compare Patella pygmoia, Dunker, Moll. Jap. p. 24, pi. iii, 

 f. 20, 1861. 



The soft parts of a single live specimen, examined at Mon- 

 terey, appeared to resemble the other species of this genus ; 

 unfortunately, it was afterwards lost, ami the opportunity of 

 examining the dentition with it. Some twenty specimens were 

 obtained at the same locality. These were exceedingly interest- 

 ing, as they presented every variation in form, from wide, oval 

 and nearly flat, to narrow, triangular, high and very compressed. 

 The extreme apex is almost always black. It is usually fur- 

 nished with a few dark brown stripes, radiating from near the 

 apex but seldom reaching the margin in adult specimens ; these, 

 however, are wanting in some specimens. In all its forms it is 

 a well marked species, and, while resembling Dunker's species, 

 cannot be united with any now known from the California coast. 

 It is known from Monterey and Baulinas Bay ; I obtained a 

 single dead specimen at Sitka. Dr. Carpenter proposes to re- 

 name this form specifically "casto" and to apply the term "tn- 



