110 PROCEEDINGS OF THE ACADEMY OF [1879. 



to try to determine, if the D. laevis should happen to be the D. 

 obvelnta of 0. Pr. Midler, as supposed by Loven. ' In many 

 cases the authors of the present time are unable to determine 

 the species described by authors of late date; it is in most 

 cases still more impossible to determine the species described by 

 elder authors. Better to leave those names of the past to obliv- 

 ion. Science, after all. ought not to take notice of an}* Nudi- 

 branchiate, that was not anatomically examined; as without such 

 examination it is in many cases not possible even to determine 

 the genus, to which in reality the species belongs. The form 

 described and figured by Alder and Hancock as D. repanda is on 

 the contrary determinable, and this name ought to be preserved, 

 although perhaps identical with the elder denominations of Linne 

 and of Miiller. 



Of this species I have had five specimens for anatomical exami- 

 nation; two kindky sent me by Mr. Friele, of Bergen, and obtained 

 in that vicinity; two from Samso, Kattegat, and from the Island 

 of Zeeland (Denmark), and one from the neighborhood of Kiel, 

 for which I am indebted to the friendship, of Prof. Moebius ; the 

 individuals agreed in their internal and external structure. 



The color of alcoholic specimens was uniformly white or yel- 

 lowish-white. The Norwegian specimens were 11-19.0 mm. long, 

 6.5-8.0 mm. broad, and 3.5-0.0 mm. high. The breadth of the 

 foot was 2.0-4.5 mm., of the mantle-edge 1.5-2.5 mm.; the height 

 of the rhinophoria 1.2-2.0 mm., of the gill 1.5-2.5 mm ; the cor- 

 responding measurements of the Danish specimens were 20.0-23 0, 

 14.0-15.0, 8.-9.0, 4.-0.0, 3.5-3.75, and about 2.0 and 3.0 mm. The 

 length of the individual from Kiel was about 8.0 mm. 



The form was rather depressed, the outer part of the mantle- 

 edge not thick. The back was covered all over with small and 

 very small papillae, obtuse or more pointed, low and rounded. 2 



The rhinophorial orifices were not prominent, but were slightly 

 crenulated on the margin. The club showed fifteen to twenty 



1 Loven, Ind, p. 4: "Z>. obvelata, M. (non C. Fabr. non Johnston, non 

 Bouch. Chant.) B. repanda, A. & H. Morch, on the contrary (Faun. 

 Moll. Isl., p. 202) regards the D. obvelata, Moller (Ind. Moll. Gronl.) non 

 Miiller, as identical with the D. repanda of Alder and Hancock. 



2 Xo trace of the characteristic yellow spots was to be seen on the mantle- 

 edge. 



