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Aphanodactylus n. g. 



I propose this new genus for one species, which does not fit into any of the various 

 genera. The external maxilHpeds, which are longitudinally directed and subparallel to each 

 other, and the ischium of which is distinctly longer than the merus, agree with those of the 

 Aesthenognathinae. On the other hand the 9 of the species, on which the genus is based, has 

 its carapace nearly twice as broad as long and this, together with the occurrence of the species 

 in tubes of Annelids, suggests some affinity to Pinnixa, but the walking legs are short, 

 scarcely as long as the breadth of the carapace and their dactyli are so extremely, 

 minute, as to be almost invisible. It is this last character that is expressed in the 

 generic name. 



The type and only species is : 



I. Aphanodactylus sibogae n. sp. PI. i8, Fig. 2. 



Stat. 313. Sapeh Bay, north coast of Sumbawa. Depth up to 36 m. i cf, i 9- I" tubes of 

 a TerebelHd (Lciinia). 



The "small crabs obtained present a smooth and shining carapace, entirely glabrous and 

 distinctly flattened. As will be seen in the figures (2 and 2 a) the sexes present remarkable 

 differences: in the 9 the carapace is barely twice as broad as long, but in the 

 cf its breadth is less than lY., times its length; besides in the former sex the 

 carapace is more strongly vaulted quite anteriorly and its lateral margins are less acute than 

 in the cf- Gastric and cardiac region, separated by an obscure cervical groove, are more or 

 less distinctly outHned by narrow, interrupted grooves; hepatic and branchial regions are 

 incompletely separated, and the former presents two pits, placed in an oblique line, branchial 

 regions scarcely declivous in their postero-lateral parts. 



The front is faintly bilobed in dorsal view ; its deflexed anterior margin is somewhat 

 angular in facial view. The eye-stalks are short, slightly movable and much flattened : in dorsal 

 aspect of the animal they look cylindrical, but broadly-oval or rather triangular in anterior 

 view. .Eyes are well developed, cornea rather large, chiefly on the ventral side of the peduncle, 

 pigment black. Fronto-orbital distance in cf almost exactly one-half, in 9 less than four-tenths, 

 of greatest breadth of carapace. Lateral margins of carapace keeled, entire, not hairy and 

 regularly curved, anteriorly much more so in 9 than in cT, owing to the proportionally much 

 greater breadth of the carapace in the former. Posterior margin of carapace in 9 concave, 

 nearly lY^ times the fronto-orbital distance; in cT this margin is straight and shorter than the 

 distance between the tips of the eyes. 



Antennulae small, somewhat obliquely-folded, separated by a narrow septum. Antennae 

 short, standing in the orbital hiatus, flagellum very short in the 9, made up of 2—3 joints 

 only, longer in the c?, in which it consists of about 7 joints and reaches to the lateral end 

 of the orbit. Pterygostomian and subbranchial regions smooth and glabrous, the latter parts 

 hairy only above bases of legs; a deep, hairless groove runs from the lateral ends of the very 

 short, almost linear epistome laterally and backward, accompanying the postero-lateral margins 



13s 



