THE ROTIFERA OF THE SCOTTISH LOCHS. 183 



NOTOMMATA PUMILA, n. sp. By C. F. Rousselet, F.R.M.S. 

 (Plate VI. figs. 25a to 25c.) 



Specific characters. — Body stout, elongated, plump and rounded dorso-posteriorly ; 

 the head remarkably small, less than half the width of the body immediately behind it, 

 tubular, and surmounted by a tuft of vibratile cilia, without auricles or other prominences ; 

 small clear brain with small cervical eye on the under surface near its posterior extremity. 

 Foot stout and rounded, carrying two small, pointed, slightly recurved toes, deeply 

 shouldered on the dorsal side of their extremity. Size — length, 127 m (giro inch) ; 

 width, 54 [a. (4Y0 inch) ; toes, 14 p. (-]-§Vo" mcn )- 



Habitat. — Amongst moss in Caledonian Canal near Fort- Augustus, Scotland. 



I found this species in November 1904, by washing out damp moss kindly sent to 

 me by Mr James Murray from the Caledonian Canal ; but it appears it had previously 

 been observed in January of the same year by this gentleman, and I could readily 

 recognise it from his sketches. 



The peculiar formation of the small tubular head gives the animal a striking aspect, 

 which is only shared by Miss Glascott's Notommata gigantea, with which it has 

 indeed considerable resemblance ; and if it had not been for the peculiar structure of its 

 toes and its diminutive size, I would have been inclined to refer it to that species. 



The integument is white, transparent, soft, and yet with a certain amount of 

 stiffness, so as to always maintain the animal's shape. Posteriorly, a broad triangular 

 fold indicates the beginning of a stout, jointless foot, which carries two short recurved 

 toes, of peculiar and characteristic shape, distinctly and deeply shouldered at the 

 extremity ; an enlarged figure of the toes is given in fig. 25c. 



A clear brain of moderate size carries a small red eye on its under side. 



The mastax is of large dimensions for the size of the animal, and contains powerful 

 and complex jaws of forcipate type (fig. 256). The manubria in particular consist of 

 two separate chitinous rods on each side, and joined at their extremities. I do not 

 remember a similar structure in any other Rotifer. The unci are broadened plates, 

 apparently without teeth — at least I was unable to detect any. Above the unci were 

 seen some apparently loose and curved chitinous rodlets, which remained in position 

 after dissolving the soft parts with caustic potash. The rami are small, and their exact 

 shape and structure difficult to observe. In fig. 25b 1 have represented what I was 

 able to make out of the incus ; the fulcrum is a narrow and short rod, curving 

 inwards and broadening at its base. 



Dorsal and lateral antennae are present in their usual positions. A large stomach 

 and intestine fill the greater part of the body cavity ; the other organs are quite normal 

 and call for no detailed description. 



Notommata gigantea, with which I have compared this new species, is vastly 



larger, reaching 726 n (-^ inch) in length, according to Miss Glascott, has very 



small toes, which are not shouldered, and the mastax also is small and apparently 

 TRANS. ROY. SOC. EDIN., VOL. XLV. PART I. (NO. 7). 25 



