34 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. xxviir. 



a pedicel bearino- two eyes similar to those of Troinltidinin. The abdo- 

 men is provided with two or more shields, according to the species. 

 The ventral openings are very large and close together, each closed by 

 flaps or valves. The mouth-parts are small and obscure, but the palpus 

 is stout, tive-jointed, the first and third joints very small, the penulti- 

 mate ending in a curved spine, the last forming a '"thum})." The 

 mandibles are stout and terminate in a curved claw. They are con- 

 cealed in the large conical rostrum. The species are ])rown in color. 

 Very little is known regarding their habits and nothing as to life his- 

 tory. They occur in moss, among fallen leaves, or in moist places. 

 They move very slowly and feign death when disturbed. But one 

 genus, ( 'H'ciihis, is known. Several species occur sparingly in southern 

 Europe and noi'thern Africa. One, C;i-ciilii>< amrrlcanus Banks, was 

 discovered b}" Hu])bard in southern California. 



Family HYDRACHNID.E. 



Since O. F. Miiller described the Danish speuies in 17S1, the water 

 mites have attracted more attention and study than any other family 

 of Acarina. A lai'ge number of important papers have been published, 



particularly on the European fauna, 

 and a recent number of " Das Tier- 

 reich'' (fascicule 13) is devoted to 

 them. The body is commonly short, 

 usually high, and sometimes nearly 

 spherical. It is en- 

 tire, there being no 

 division into ceph- 

 alothorax and ab- 

 domen. The legs 

 arise close together 

 on the anterior part 

 of the venter, and often in a radiate arrangement. 

 They have one or two simple eyes each side; in 

 some cases these are situate close to the median line. 

 The tegument is often soft, but sometimes provided 

 with dorsal shields or covered with a pitted cuirass. 

 The mouth parts are often hidden under the anterior 

 margin of the cephalothorax. The beak (rostrum 

 or capitulum) is usually elongate pyriform, and the mandibles are two- 

 jointed, with a claw-like terminal joint; sometimes they are elongated 

 into needle-like piercing organs. The palpi (maxillary) are of four 

 or five joints, the basal one often ver}' small, the apical one sometimes 

 folding against the penultimate. The palpi var}^ greatl}^ in shape 

 and are of great value in classilication. The legs ai'e usually of seven 



Fig. 53.— Limnochares: venter. 



Fig. 54. — Limnochares; 

 eves and dorsal 



PLATE. 



