566 GASTROPODA. [Opisthobranchia. 



Genus 2. ROSTANGA, Bergk, 1879. 



Rostanga, Bergh, Archiv. fur Naturgesch., 1879 ; Gatt. Nord. Dorideu. 

 Type : Doris coccinea, Forbes. 



Animal having tke back of tke body covered witk minute rougk 

 tubercles ; branchiae simply pinnate. A labial armature is present. 

 Tke teetk of tke radula are of two different kinds tke inner teetk 

 are skort and kooked, witk a broad base ; tke external teetk are 



long, tkin, and bifid. 



KEY TO SPECIES. 



A. Mantle with minute cylindrical tubercles, crammed with straight 



granulated spicules ; gill formed of 9 simple or bipinnate 

 members . . . . . . . . . . . . muscula. 



B. Mantle densely covered with erect small tubercles ; gill formed of 



8 bipinnate members . . . . . . . . . . rubicunda. 



>i 

 1. Rostanga muscala, Abrakam, 1877. Plate 23. figs. 23, a-d. 



Doris muscula, Abrah., P.Z.S., 1877, 205, 256, pi. 29, f. 6, 7 ; M.N.Z.M., 126, 

 Rostanga muscula, Abrah. : Eliot, P. Mai. S., vii, 1907, 328, 339. 



Body elliptical, convex. Mantle covering tke kead and tke foot, 

 but not laterally flattened or extended into a border ; it is covered 

 above witk minute cylindrical tubercles, twice as long as tkey are 

 broad, and crammed witk straigkt granulated spicules. wkick are 

 often swollen in tke middle. Rhinophorcs retractile into cavities of 

 wkick tke borders appear to kave been raised in life and to kave borne 

 small pointed tubercles. Tke branchial, 9, simply pinnate or bipin- 

 nate, small, retractile ; tke margin of tke cavity is fringed witk small 

 elongated tubercles. Tke oral tentacles are distinct, knear, and ratker 

 flat. Foot oblong, rounded at tke ends, witk a deep transverse groove 

 in front and tke upper lamina notcked ; it does not extend bekind 

 as far as tke mantle-edge. Colour (in spirit) greyisk, witk an indis- 

 tinct brownisk longitudinal band extending from tke rkinopkores 

 to tke branckia?, and bordered on eitker side by a bluisk band, tke 

 colour being due to pigment disposed between tke dorsal tubercles in 

 a reticulate pattern, but not on tkem. 



Lengtk, 13 mm. ; breadtk, 9 mm. (type). 



Tkere are small granules or columns in tke labial cuticle, but tkey 

 are not arranged in a plate. Tke formula of tke radula 69 x about 

 82 + + 82. Tke innermost lateral is kamate, and bears on tke 

 inside numerous (30 or more) fine comb-like denticles. Tke second to 

 tke eigktk laterals are also kamate ; tke skaft is slender and pointed, 

 tke base stout witk a large projection. Tkese teetk gradually pass 

 into tke tkird form, wkick prevails from 9 to 36. Tke skaft gradually 

 grows longer and tke base smaller, until tke wkole tootk kas tke 

 skape of a kook on a pedestal. In tke remaining 45 teetk tke base is 

 still smaller, tke skaft is longer, and tke end is split into 2-4 long 

 denticles, forming a brusk at tke tip. Tkese teetk resemble filaments 

 ratker than tke ordinary teetk of Dorids. As preserved, tkey lie in 



