180 



ON THE DORIS PLAN ATA OF ALDER & HANCOCK. 



By Sir C. K E. Eliot, K.C.M.G. 



Read IQth June, 1904. 



Geitodoris planata (A. & H.). 



Doris planata, A. & H. : Brit. Nudibranch. Moll., pi. viii. 



Geitodoris complanata, Bergh : Bull. Mus. Comp. Zool. Harvard, 1894, 



vol. XXV, p. 163, pi. iv, fio^s. 13-18 ; pi. v, figs. 1-5. 

 Flatydoris planata, Garstang : journ. Marine Biol. Assoc, vol, i, No. 4 



(1890), pp. 445-6. 



Alder & Hancock's Doris planata has been attributed to the genus 

 Platydoris, but, in so doing, authors seem to have attended only 

 to the description given opposite the plate (No, viii), and to have 

 neglected the definition of the characters as given in the synopsis at 

 the end of the work (l.c, pt. vii, p. 42), D. planata there comes 

 under the heading — 



" ** Oral tentacles linear. 



Lingual spines of two ktfids, various : no central spine. Occasionally 

 with a spinous buccal collar.''^ 



Erom this it follows that the animal has a radula with differentiated 

 teeth of two kinds, and possibly a labial armature, two chai'acters 

 which do not belong to the genus Platydoris. 



Through the kindness of Mr, Allen, of the Plymouth Laboratory, 

 I have received five specimens of the animal known there as Platydoris 

 planata. They present striking differences in appearance, but agree 

 in structure, and are no doubt correctly referred to the same species. 

 Three are greenish grey, soft in texture, and flat in shape. The 

 mantle edge is ample ; the back slightly arched, and covered with 

 soft tubercles of various shapes and sizes. The largest is 16 mm. 

 long, 11 '5 broad, and 5'5 high. The two remaining specimens are 

 white, and much bent in shape, but apparently more stoutly built 

 than the others. The skin seems, at first sight, smooth, but is really 

 finely granulate. The measurements of the larger specimen are — 

 length 12'5mm. (probably representing at least 20, if straightened), 

 breadth 8-5, height 6. Unless the contrary is stated, the following 

 notes apply to both chasses of specimens. The foot is deeply grooved 

 and notched in front, fairly broad, and does not project behind the 

 mantle. The tentacles are distinct and conical. The dorsal integu- 

 ments are full of strong spindle-shaped spicules. The pockets of the 

 rhinophores and branehige are slightly raised, tuberculate and crenulate, 

 but not lobed. The rhinophores have about 25 perfoliations. Of the 

 branchiae Mr, Garstang (l,c.) says that they are six, but that in one 

 specimen the third on each side was deeply bifurcated, and in the 



