THREE RARE SPECIES OF HYDRACARINA 61 



pre-eminently, the absence of a dorsal plate and the nature of the 

 papilla?. The gland pores are very small and inconspicuous, with 

 the exception of a pair on the dorsal surface, distant from the 

 frontal margin about one-third of the body length. This pair has 

 a small portion of the surrounding area slightly chitinised, sug- 

 gesting a rudimentary type of those small plates generally to be 

 found when the antero-dorsal plate is wanting. The papilla? of the 

 anterior, middle, and posterior areas differ in character; those of 

 the anterior portion are low and rounded, those of the posterior 

 are long and conical with the sharp apices directed posteriorly, 

 while the middle area is occupied by an intermediate form. 



Koenike did not describe the capitulum or palpi of the male. 

 Viets, however, later described but did not figure those of the 

 female. 



The Scottish specimen measured about 3 mm. in length. The 

 eye capsules are large and prominent, with an intraocular distance 

 of '52 mm. Each capsule is about "15 mm. broad by *i8 mm. long. 

 Of the existence of a median eye, neither Koenike nor Viets make 

 any mention. My specimen was torn along the median line where 

 the eye would probably be found, so that I also am unable to 

 afford any information on the point. 



Viewed laterally, the capitulum measures 1*09 mm. in length, 

 22 mm. at its broadest part dorso-ventrally, and "19 mm. at the 

 base of the rostrum. The latter curves moderately downwards. 

 The mandibles follow the same curve and are 1-5 mm. in length 

 from the minutely serrate tip to the club-shaped heel. The distal 

 portion has a thin carina and measures there 105 mm. in breadth. 



The palpi are ro2 mm. in length. Viets' description of those 

 of the female holds good for the male. A conspicuous feature is 

 the constriction on the proximal flexor surface of the third segment. 



The first pair of epimera have their greatest width at the point 

 where they approach nearest to one another, the distance there 

 being -045 mm., increasing to "105 mm. The second pair are 

 broadest at their outer extremity, and the posterior margin has a short 

 subcutaneous process. The first two pairs have each their inner 

 extremities rounded, so that they stand out more or less distinctly 

 from one another. The third pair have the sides nearly equidistant, 

 but the inner anterior corner which lies well forward in the female 

 is truncate in the male, the thick margin being looped sub- 

 cutaneously to appear again as a short spur extending to the 

 genital shield. The fourth pair have the inner posterior corner 

 expanded into a broad process whence the specific name with 

 a subcutaneous edging and a spur extending from it. Koenike 



