ACARINA FROM THE JUAN FERNANDEZ ISLANDS 57 1 



We are reminded of this by the Juan Fernandez collection which although 

 comprizing only a small portion of the acari of those islands nevertheless con- 

 tains at least one very curious form, which is the type of the present genus. 



Diagnosis: Dorsal side completely covered by a white waxy 

 secretion. Propodosoma long, pointed, with neck-shaped, constricted 

 base. Hysterosoma reniform, much wider than it is long, with con- 

 cave dorsal side. Lamellae very thin and broad, almost horizontal 

 blades. Pseudostigmata very large, trumpet-shaped, projecting; 

 pseudostigmatic organs long, filiform, curved backwards. Rostrum 

 sharply pointed, with terminal deep incision. Mandibles very long 

 and narrow, with small chela. 



5. Cerocepheus mirabilis n. sp. — Figs. 32-41. 



Length 780 [i. Length of propodosoma 340 ji, width of propodosoma 

 190 [J.. Length of hysterosoma 440 {x, width of the same 560 jt. 



Colour dark chestnut brown. 



Texture dull and rough. The entire dorsal side of the whole body is 

 covered by a white waxy matter, so that only the tips of the legs are visible 

 from above. This wax is probably secretated through pores which are placed 

 at the base of the propodosoma, round the lateral and posterior margin of the 

 hysterosoma and between the last pairs of the dorsal hairs (fig. 32). 



Propodosoma very long and narrow, almost twice as long as it is wide 

 at the base. Rostrum sharply pointed and with deep narrow incision (fig. 32) 

 which reaches half way to the translamella. The posterior part of the incision 

 is surrounded by a horse-shoe-shaped plate of thicker cuticle, with radiating 

 striae. Propodosoma distinctly set off from the hysterosoma by a short, neck- 

 shaped constriction. 



Lamellae very large, thin, almost horizontal blades which start in front of 

 the pseudostigmata from a narrow base, widen suddenly and are then of al- 

 most even width throughout, extending forwards with broadly rounded cusps 

 which extend almost to the top of the rostrum where they nearly meet. Trans- 

 lamella a narrow, thickened ridge. Lamellar hairs inserted on the cusps a short 

 distance from their anterior margin, slender and curved slightly inwards, then 

 outwards near the top. 



Interlamellar hairs very long, flexible, whip-like, inserted on a level with 

 the base of the lamellae on low projections. 



Pseudostigmata of exceptional size (figs. 34) shaped as large trumpets, 

 directed horizontally outwards and bent shghtly forwards. Their anterior edge 

 has a sharp tooth pointing forwards, the posterior edge has a low blade, which 

 fits in between two teeth at the anterolateral margin of the hysterosoma, and 

 is constricted at the base. 



The interior is shaped like a trumpet, with thin cup-shaped rim narrowing 

 gradually and curved sharply forwards at the end. Pseudostigmatic organs 

 curved obliquely outwards and backwards where they emerge from the cup, 

 rodlike, of even width throughout and slightly pointed at the end. 



