240 F. W. GAMBLE, B.SC. 



1844. LEPTOPLANA ATOMATA, Oersted (16). 

 ? 1845. ,, Drcebachensis, Oersted (21). 



? 1853. Plan aria maculata, Daly ell (29). 



1865. Leptoplana ATOMATA, Johnston (38). 



1874. „ „ Mcintosh (45). 



Length 10 — 12 mm. 5o% oval, slightly wider in front than behind, 

 rounded at both extremities. Colour variable, the ground-tint white 

 or brown, spotted with reddish-brown, white beneath. Ova are seen 

 as white dots over the upper surface. Two " tentacular " and two 

 cephalic groups of eyes are present. The only known fact about the 

 genital organs is that the penis has a bulbous base, and a transparent 

 terminal duct which contains a hard stylet. 



Habitat. — Coast of Scotland (Fleming) ; Orkneys and Shetlands 

 (Forbes and Goodsir) ; Firth of Forth (Dalyell) ; St. Andrews 

 (Mcintosh). 



Distribution.— Naples (Delle Chiaje), coast of Holland, Germany, 

 Denmark, Baltic (Droback). 



Planaria atomata has never been described in a sufficiently 

 diagnostic way to render possible the identification of specimens with 

 it. Consequently the above synonymy is very probably incorrect, 

 but it is in no one's power to tell what the authors quoted did mean 

 by their Planaria atomata. Thus Forbes and Goodsir, Fleming, 

 Johnston, and Mcintosh merely give the name and the record. Even 

 those (as Miiller and Oei'sted) who vouchsafe anatomical facts state 

 the size, the form of the body, the position and arrangement of the 

 eyes, and the form of the penis, and these do not by themselves, 

 signalise a species of Leptoplana. Evidently a fresh and full descrip- 

 tion of a form is needed, which, if it differs from other existing species, 

 may be called atomata, although its unity with the species of that 

 name can only extend to the points mentioned. Comparisons with the 

 new fully described atomata would henceforth be possible. Such a 

 full account of a species agreeing in the form of the body, the position 

 of the eyes, and the composition of the penis is to be found in Jensen's 

 description of Leptoplana Droebachensis. 



The small differences that justified Oersted in separating these two 

 species were the following : 



