OPISTHOBRANCHIATE MOLLUSCA FROM MONTEREY BAY. 



141 



The large lobulated blood gland lies upon the front portion of the anterior genital mass, extending 

 transversely from the median line toward the right side for a distance of 10 mm. It is flattened, thin, 

 and deeply divided into lobules. 



Hermaphroditic gland large, concealing the liver; the hermaphroditic duct, narrow at first, after 

 a course of about 8 mm. passes into a very long, more dilated portion, which is coiled in irregular 

 corkscrew-like windings against the inner posterior flattened face of the large hemispherical mass 

 formed by the nidamental and albumen glands. Straightened out this duct measures about 60 mm., 

 a length nearly equal to that of the whole animal. Near the anterior end of the above glands it divides 

 into the the .spermatic duct and the oviduct. The sj^ermatic duct passes almost directly into the 

 prostate gland, which is large, slightly flattened, looped closely upon itself, minutely lobulate, and has 

 a total length of about 20 mm. and a maximum diameter of about 3 mm. Leaving the distal end of 

 tlie prostate gland, the vas deferens, after a short (2 mm.) narrow portion, dilates into the long ampulla. 

 This oriian is of a cylinilro-conical shape, slightly broader (2 mm. ) at its proximal end than at its distal 

 one, alxiut 5 mm. in length, and with thick muscular walls. Beyond the ampulla the duct continues 

 for about 8 mm., dilating gradually and passing into the penis .-lieath, which is alx)ut 6 mm. long by 

 » mm. broad. Upon its dorsa! surface lies the small, rounded u'cniiul iiaii-dinn borne upon a branch of 

 tlie pleural commissure. The glans penis and the distal end "i the- \a- deferens are closely set with 

 minute, erect, daw-like hooks (pi. xi.x, fig. 64) for a distance of about 2 mm., becoming more scattered 

 and fewer toward the inner limit of their occurrence. Length of teeth about 42 mm., diameter of base 

 about 12mm., their tips directed towardjhe opening of the duct in the completely retracted glans. 



The oviduct is as usual in the genus. The very large spermatotheca, about 10 mm. in diameter, 

 occupies nearly the whole of the upper portion of the genital mass; its inner duct is short and receives 

 the short duct of the 5 mm. long, pear-shaped spermatocyst, its distal portion, about 8 mm. long, grad- 

 ually dilates into the vagina. 



The above structural characteristics distinctly mark out this form as a species of Triopha totally 

 ilistinct from the remaining three Pacific coast species. During the summers of 1893 and 1894 it was 

 quite abundant U]ion the brown kelps, Xcreoci/KtiK and _'/.«■, ■.„//x//.v. off Point Aulon and Point Pinos. 

 Since then it has been taken at intervals from the saiiir lialiitMi. i.iit in fewer numbere, the large kelp 

 beds having almost entirely disappeared along the coast lictunn .Monterey and Pacific Grove. It has 

 never l>een taken in sliore collecting, where Triopha c<trpenlen and Triopha nidculala are common. 



Tyjie no. 18128o, V. S. National Museum. 



Radidx of species of Triopha. 



Geuns 13. FOLTCESA Cnvier. 



Polycera Cuvier, Regne .\nim'., 1817, II, p. 390; ed. 2, 1830, III, p. 52.— Bergh, Beitr. zu einer Monographic der PoIyceradeTi. 

 I. Verb. d. li. k. zool.-bot. Ges. Wien, XXIX, 1879, p. .599. System der Nudibr. Gasteropoden. 1892. p. !.t<). 



Body limaciform, nearly smooth; frontal margin digitate; rhinophores nonretractile, <-lavus 

 perfoliate; branchi;e of few leaves, simply pinnate; upon each side of the branchiae a single larger 

 <ligitiform extrabranchial appendage; tentacles short, lobiform. 



Mandibular lamellae with a winglike process above. Radula rather narrow; rhachis naked; 

 lateral teeth 2 large unequal ones and several external ones. 



Prostate lai-ge. Oilans penis armed. 



