OPISTHOBRANCHIATE MOLLUSCA FROM MONTEREY BAY. 135 



Radula nearly colorlesi?, broad, with wide median groove. Teeth in 7f)-82 rows, the last 2 or 3 

 rows incompletely developed. Rhachis narrow, averaging 19 u wide, with a single series of colorless 

 flattened plates occupying nearly the whole width of the rhachis, nearly rectangular in form, slightly 

 l)roader at anterior than at posterior end, the edges irregular in outline. Average length 0.018 mm., 

 wiilth anterior end 0.011 mm., posterior end 0.008 mm. ( PL xix, figs. 46, 48) . Pleural teeth 2, the first 

 one ( pi. XIX, figs. 46, 47« ) a simple, strongly curved hook directed vertically, its shaft somewhat expanded 

 and flattened at its posterior end and fitting closely to the second pleural tooth. Length 0.036 mm. 

 The second pleural tooth (pi. xix, fig. 47/>) strong and heavy, the shaft irregular in form, olslique, at its 

 ujiper end two strongly liooked cusps, the inner one smaller and directed inward, the larger outer one 

 being more vertical, the two together forming a crescentic figure as seen from above. Below the inner 

 hook a strong rounded elevation on the upper portion of the shaft, passing obliquely outward into a 

 riilge. The lower end of shaft bluntly rounded, bearing a slight wing-like elevation on its outer face. 

 Length of lateral tooth from end of shaft to crest 0.038 mm., diameter below inner cusp 0.011 mm. 



L'ncinal teeth 10-13 in number, closely set, pavement-like, presenting from above an arched, 

 quadrangular outline with two pointed cusps at the lower angles strongly developed in the first 4 teeth 

 (pi. XIX, flg. 46 c, (f; fig. 49 c, /), but much reduced and finally disappearing in the remaining outer 

 ones (flg. 49 g-n), which become modified into flattened plates of considerable thickness. 



Olans penis long, cylindrical, blunt, about 0.6 mm. in length by 0.04 mm. in diameter, with an 

 armature of minute thorn-like hooks arranged in 10 to 12 slightly irregular longitudinal rows 

 (pi. XIX, fig. 50.) 



Habitat: Under shelving rocks in tide pools along the coast, especially near Point Aulon and 

 Point Pinos. Not rare. Much smaller individuals of the same species have been collected at San 

 Pedro, Cal., by Prof. T. I). A. Cockerell, who has very kindly turned some of them over to me, 

 together with his notes upon the same. I take pleasure in dedicating this species to him. 



Type no. 181290, U. S. National .Museum. 



Geuns 12. TRIOFHA Bergh. 



Triopha Bergh, On the Xudibranchiate Gasteropod Mollusoa of the Xorth Pacific Ocean (Dall. Explor. of Alaska, I, Art. 6), 

 II, l.sSO, pp. 261-21)6, (al.<iO in Proc. Acad. Sci. Phila.. 1S80, p. 112). Sy.stem der N'udibr. Gasteroi>oden, 1892, p. U.S. 

 Die Opisthobranchien! Bull. Mus. Comp. Zool., XXV, 10, 1894, pp. 184-187. 



Form of body somewhat limaciform; margin of the narrow frontal lobe with a series of short 

 simple or composite granulose appendages; margin of dorsum with uodulate or short-branched 

 appendages; rhinojihores retractile, clavus perfoliate; tentacles short, calyciform, the outer margin in 

 part cleft ( auriform ) ; branchiie of few tripinnate leaves. 



Mandibular plates triangular, made up of short, closely set rodlets. Kadula rather narrow; rhachis 

 with several .series (4) of spurious teeth; pleura; with several (.3-18) rows of larger teeth; lateral teeth 

 many (10-18). 



Prostate gland large. Glans penis armed. 



This genus was established in 1880 by Bergh to receive two species of nudibranchs from the 

 Pacific Ocean. Of these the Tr. rarpenteri (Stearns) occurs in ilonterey Bay and is here given, while 

 the two following species are new but undoulitedly l>elong to this genus. 



13. Triopha carpenteri (Stearns). 



[PI. XXVII, figs. 16, 17; pi. XIX, figs, al-i^; pi. XXI, Jigs. 108,113.] 



Trio))a carpenteri Stearns, Description of a new genus and two new species of nudibranchiate moUusks from the coast of 

 Califiirniii, Proc. Cal. Acad. Sci., V, April 21, 1873, p. 78, flg. 2.— MacFariand, op. cit., p. 48. 

 Body limaciform, elongate, robust; anteriorly obtusely rounded, posteriorly rather bluntly pointed. 

 Head obliijuely flattened, semilunar, bearinga narrow frontal margin (pi. xxi, fig. 108) extending later- 

 ally beyond the rhinophores, continued behind into the less conspicuous dorso-lateral ridge, and bear- 

 ing along its whole length a large number of irregularly lobed and tulierculate papilla; (pi. xxvii, figs. 

 16-17). Dorsum slightly arched, set off from the sides b)' a series of tuberculate processes (5-9), of 

 varying size and form, borne upon an inconspicuous low ridge, in many cases almost indistinguishable. 

 The first of these processes lies in continuation with the frontal margin in the region of the rhinophore, 

 the last 2 or 3 behind the branchia;. Scattered upon the minutely granuligerous dorsum many smaller 



