1879.] NATURAL SCIENCES OF PHILADELPHIA. 87 



what flattened. The rhinophoria are smooth, scarcely longer than 

 the tentacles. The eyes are not visible externally. The back 

 throughout its whole length naked on the broader middle part; 

 laterally closely set with oblique rows of papillae, 1 about seven to 

 eight in each row, fewer in the fore and hindmost rows; the pa- 

 pillae conical, somewhat compressed, particularly in the inferior 

 parts, with the usual gill-membrane along the inner edge. 8 The 

 anus in the usual place. The sides of the body rather high, the geni- 

 tal openings quite contracted. The foot in the foremost part rather 

 broad, anteriorly rounded ; backwards gradually narrower, the 

 margins projecting a little from the sides; the tail rather short 

 (about 1.5 mm. long), merely projecting a little behind the body. 



The central nervous system is of the usual form, 3 rather flat- 

 tened ; the cerebro-visceral ganglia rounded, triangular, the pedal 

 ones a little larger, of oval form, the buccal and gastro-cesophageal 

 ganglia as usual. 



The eye is as usual, with black pigment, and with a rather large 

 lens. The otocysts could not be detected. 



The oral tube (retracted) about 1.5 mm. long, rather wide. The 

 oral glands 4 long as usual, opening in the oral tube ; whitish. The 

 bulbus pharyngeus 3.0 mm. long, with a breadth of about 1.8 mm., 

 as formerly described. 5 The mandibles also quite as in the typical 

 form. 6 The tongue long and narrow, as in the last ; 7 on the under 

 side twelve, on the end two, and on the upper side twelve teeth ; 

 also in the sheath of the radula eleven developed teeth and two 

 not fully developed plates ; the number of teeth was consequently 

 thirty-nine. 8 The form of the teeth (fig. 7, 8) was as usual ; on 



i Cf. 1. c, 1858, Tab. I. f. 1-3. 



2 Cf. 1. c, 1858, Tab. I. fig. 4-5. 3 Cf. 1. c, Tab. I. fig. 7. 



4 These glands, which have been formerly described by me as salivary, 

 cannot be so homologized, because their ducts do not pass over the com- 

 missures of the central nervous system. Glands of the same kind have 

 been found in other forms of Aeolidiidce, in the genus Aeolidiella, Bgh. 

 (Cf. my. Beitr. znr Kenntn. d. Mollusken des Sargassomeeres. Verb. d. k. 

 k. Zool.-bot. Ges. in Wien, xxi. 1871, Taf. XIII. fig. 20b, and Beitr. zur 

 Kenntn. d. Aeolidiaden, ii. 1. c. xxiv. 1874, p. 39<h, Taf. VIII. fig. Ubb). 



5 Cf. 1. c, Tab. I. fig. 8. 



6 Cf. 1. c, Tab. I. fig. 9-13. ' Cf. 1. c, Tab. I. fig. 16-18. 



8 Cf. 1. c, Tab. I. fig. 23-28. The author found in twenty-two specimens 

 of the F. atlantica thirty-eight to fifty teeth ; the number of denticles was 

 mostly six to eight, sometimes eleven to twelve, on each side ; later (Beitr. 



