inhahiting Salt Wate)\ 239 



the rest of tlie body ; maxillary palpi 5-joInted, each ending 

 in an incurved spine (the fifth joint). Mandibles large, form- 

 ing an ensiform beak nearly as long as the palpi. Claws 

 long ; the upper hook minute ; a single row of hairs on the 

 underside of the lower hook, forming a brush. Otherwise 

 closely allied to HydracJma. 



The body is globular, convex above, with the abdomen ob- 

 tusely rounded behind, the skin being minutely lineated. It 

 is blackish when alive, with the head and edge of the body 

 white. The head is minute, conical, subacutely pointed in 

 front. The maxillary palpi are 5-jointed, a little more than 

 twice as long as the head, and about one-fourth as long as the 

 fore legs ; the second joint short ; the third joint one-third as 

 long as the entire palpus ; the fourth as long as it is thick ; 

 the fifth minute, and carrying a long, slender, slightly in- 

 curved spine bifid at the tip, the outer fork projecting con- 

 siderably beyond the inner one. The mandibles form an 

 ensiform acute beak, reaching to the middle of the terminal 

 palpal spine. The two eyes are remote black dots situated on 

 the anterior fourth of the body; over the insertion of the second 

 pair of legs, and just in front of them is a well-marked trans- 

 verse groove crossing the body. The legs are 6-jointed, much 

 alike in structure, moderately hairy. The claws are alike in 

 size, the hook being moderately curved, rather long, bifid at 

 the end, the upper fork being much the smaller, especially on 

 the anterior pairs, forming a small acute tubercle ; in the 

 middle of the underside of the claw (on all the feet) is a brush 

 of fine hairs of equal length, arranged in a single row. On 

 the penultimate joint of the anterior tarsi are five stout hairs ; 

 on the other tarsi three, the two proximal hairs being con- 

 tiguous. External female genitalia with two bivalve con- 

 tiguous plates, like those of //. formosa^ Dana and Whelpley. 

 Length '07 of an inch. The body of the young is whitish, 

 longer, more ovate than in the adult, the abdomen being a 

 little pointed behind. 



With the exception of Philippi's Pontaraclina pimctulata 

 (Wiegmann's Arcliiv, 1840, vol. vi. p. 191, pi. 4. figs. 4, 5), 

 which was discovered by him in the Bay of Naples (he does 

 not state at what depth ; consequently I infer that it was in 

 shallow water) , the species under consideration is the only one 

 which, so far as I am aware, has been found to be exclusively 

 marine*. The genus Fontarachna is very different from Hij- 

 drachna and Thalassaraclina ; and I should judge that it rather 

 approaches Atax. It differs from Thalassaraclina in the 

 shorter, unarmed palpi, and in the apparent (Philippi does not 



* [Mr. Gosse has described (Ann. Nat. Hist. ser. 2. vol. xvi. pp. 27 & 

 305) three species of marine mites found on the British coasts. — Ed. Ann.~\ 



