194 BRITISH TYROGLYPHID^. 



dry between tides ; or living in places where fresh water 

 trickling over rock becomes mixed with salt spray, and 

 the growth of green algse takes place ; but they are 

 evidently capable of living comfortably under water. 

 Thirdly, the ambulacra of the two anterior pairs of 

 legs are quite exceptional. I am not aware that any- 

 thing like it occurs again in any of the Acarina ; per- 

 haps the nearest thing to it is in the true SarcoptidaB 

 (the itch-mites such as Sarcoptes, Psoroptes, etc.), and 

 in the above-named genus Eemisarcoptes. But in all 

 these cases the long peduncles on which the ambulacra 

 are mounted are stiff and chitinous, and can only be 

 moved as a whole ; whereas in Lentungula the peduncle 

 is soft, and can be flexed in any direction at the will of 

 the creature. Moreover in Lentungula it bears a claw 

 only, and in the other cases it bears a sucker only. 



The Rostrum, in the species yet known, is practi- 

 cally an oral tube, having a certain resemblance to that 

 of the Gramasidse. It may be exposed, as in the British 

 species L. algivorans, or hidden by the hood formed by 

 an advancing, part of the remainder of the cephalo- 

 thorax, as in the Continental species L. fusca. 



The Maxillary Lip is of the ordinary type in the 

 family, but shows its dual origin somewhat more plainly 

 than is generally the case. 



The Palpi appear to vary in number of joints in 

 different species. L. algivorans has five free joints, 

 and L. fusca only two, the other or others being fused 

 with the maxillary lip. All through the Sarcoptidae 

 and Tyroglyphidae the palpi are in a very rudimentary, 

 or debased, condition, and the extent to which they 

 are fused with the maxillary lip varies. 



Labium. There is in L. algivorans a small, triangu- 

 lar chitinous piece below the maxillary lip, which might 

 possibly be considered to be the homologue of a labium. 



Mandibles. These are of the ordinary chelate type ; 

 in the known species they are short and powerful, with 

 few teeth. 



Legs of moderate length in the known species ; they 



