HARDWICKE'S SCIENCE-GOSSIP. 



i6i 



In all probability, many or most of the species 

 recorded from the above countries, are also common 

 to Britain, if observers would but search systemati- 

 cally for them, and place on record [such forms as 

 they may chance to meet with. It is for this purpose 

 of awakening interest, and so helping to increase our 

 knowledge of our indigenous Gastrotricha, that this 

 communication is written. 



In November, 1S90, whilst searching for Rotifera, 

 I came across, in water from a pond near Leyton- 

 stone, Essex, some specimens of a Dasydytes which 





'Vl".-^' 



Fig. 142.— Dasjfdyies hisetosunt. 



does not appear to be identical with any member of 

 this genus included in Dr. Zelinka's recent mono- 

 graph, above referred to. Some half-dozen indivi- 

 duals were seen in all, and afforded me opportunity of 

 making the following observations, and of securing a 

 fairly accurate sketch of the animal. I propose to 

 call this Dasydytes hisetosum. 



The body is plump and of oval outline when seen 

 dorsally, rounded posteriorly, and of course without 

 any caudal fork ; anteriorly, the trunk narrows to 

 the neck, which latter is very distinctly marked off 

 from the head. A couple of transverse wrinkles in 



the skin are more or less visible, crossing the neck. 

 The head is large and wide, three-lobed in dorsal 

 aspect, the lateral lobes prominent like puffed cheeks ; 

 the width of the head is nearly twice that of the neck, 

 and about three-fourths that of the body at its widest 

 part. Both head and neck are usually considerably 

 flattened, excepting the lateral head-lobes, which are 

 somewhat globose and thicker than the central region 

 of the head. The trunk is not at all flattened, 

 appearing circular in optical cross-section. 



The head is covered on all its surfaces, dorsal, 

 lateral, and ventral, with numerous long vibratile 

 cilia, directed backwards. 



The body is furnished, on its lateral surfaces, with 

 a few rather short, very thin and delicate, somewhat 

 appressed bristles, apparently arranged in about three 

 longitudinal rows on each side, though this is a point 

 difficult to determine. I do not think any bristles 

 occur on the dorsal surface proper. These setae occur 

 also on the sides of the neck, and, in side view of 



the animal, are seen to be directed dorsally and 

 posteriorly ; none are nearly so long as the terminal 

 caudal bristles to be described. The animal's 

 ventral surface is longitudinally furred with active 

 cilia, like all the members of the Order. The body 

 is rounded behind, and has a terminal projection, 

 convexly truncate, from which are given off two long, 

 thin and delicate setse, quite one-third the total 

 length of the animal's body and head, set wide apart 

 at their base, and carried parallel or with their tips in 

 contact. It is on account of these two conspicuous 

 tail-bristles, which serve by their great length to 

 distinguish this new form from its allies, that I have 

 selected the specific title " bisetosum " for the 

 creature. 



The mouth is a permanently projecting tube, 

 surrounded by a ring, at the extreme front of the 

 head. It is continued into a long oesophagus, about 

 one-third the total length of the animal, having a 

 narrow but distinct, straight lumen, and very thick 

 walls, on which I could detect no cross-striation. 



