water-beetles of Japan. 461 



Oosternum, recently established for a Central American 

 insect. Only another solitary individual of this minute 

 species has been brought back by Mr, Lewis, found at 

 Nagasaki on the 1st of March, so that it appears to be 

 a rarity. 



Peratogonus, n. g. 

 Corpus subrotundatum, convexum, supra et infra politum. 

 Labrum exsertum. Mentum planum, obsolete punctatum, opacum, 

 pubescens. Prosteruum in medio parvum, utrinque ante coxas 

 nullum. Femora margine auteriore recto, posteriore angulariter 

 dilatato, glabra. Pedes iutermedii valde distantes, mesosterni 

 processu latissimo, brevi, in medio anterius angulariter prominulo. 

 Pedes posteriores breves, tarsis perbrevibus. 



The above characters readily distinguish this curious 

 little insect from all the other genera of SpJueridiida yet 

 known. It may be placed between Oosternum and 

 Deltostethus. The five joints of the very short tarsi 

 are each almost of one length, and the claws are very 

 minute. 



Peratogonus reversus. 



Rotundatum, convexum, nigro-piceum, politum ; antennis, palpis 

 pedibusqiie testaceis ; elytris profunda striatis, striis internis ad 

 basin subtilioribus, ibidemque discrete punctatis. Long. 2 mm. 



The head and thorax are almost impunctate, but the elytra are 

 scored by very coarse striae, those towards the sides being directed 

 obliquely upwards ; the interstices, like the head and thorax, are 

 shining and almost impunctate ; there are only eight true striae, 

 the two outer ones being replaced by a few coarse serial punctures. 

 The metasternum has a few very coarse and deep punctm-es on 

 each side. 



Found in a few examples at Nagasaki in March and 

 April. 



Criiptopleurum subtile. 

 Cryptopleiirum atomarium, var. ?, Sharp, Trans. Ent. 

 Soc. Lond., 1874, p. 420. 



Breviter ovale, parce pubescens, ferrugineum, thorace in medio 

 plus minusve infuscato, capite, prosterno pectoreque nigricantibus, 

 antennis pedibusque testaceis ; prothorace subtiliter crebre punc- 

 tate, elytris sat profunde striatis, striis anterius evidenter punctatis, 

 interstitiis sat crebre obsolete punctatis. Long. 2 mm, 



