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strongly convergent forward, the terminal segment is more triangular, and the penultimate 

 segment longer than the preceding one. 



The measurements of the cT given below nearly exactly agree with those of a specimen 

 of Pt. spinicarpus measured by de Man ^). 



Dimensions in mm.: 



Distance between external orbital angles . 

 Distance between tips of postero-lateral teeth . 



Length of carapace 



Breadth of anterior margin of front 



Length of chela 



Height of palm 



Breadth of ischium of ext. ma.xillipeds. 



Breadth of exognath of ext. maxiUipeds 



Breadth of base of abdomen .... 



Breadth of base 



Length 



Length of terminal segment of abdomen 



Length of meropodite 



Breadth of meropodite 



Length of carpo- -|- propodite 



Length of dactylus 



of penultimate segment of abdomen 



of penultimate pair of legs 



8.25 



4-4') 

 2.6 ■-) 



3-3") 

 1 1. — 



3-25 

 II. 5 



7-5 



2. PtychognatJms afflnis de Man. 



1S95. Ptychognatlins affinis de Man. Zool. Jahrb., Syst., Bd 9, p. 97, Bd 10, 1898, pi. 28, f. 2[. 



Stat. 115. Kwandang Bay, north coast of Celebes. 11 sp. juv. (all cf), in river. 

 Stat. 179. Kawa Bay, west coast of Ceram. i cf- 



The original specimen from Atjeh was not full-grown, and this circumstance induced 

 DE Man to presume, that perhaps this species was only a young stage of Pt. spinicarptis^ with 

 which it shows the nearest affinity; though the exognath of the external maxilliped in Pt. affinis 

 is only slightly broader than the ischium, but twice as broad as the ischium in Pt. spinicarpus, 

 this difference might be perhaps accounted for by the well-known fact that the exognath in 

 species of Ptychognatlnis is proportionally narrower in young individuals than in the adult ones. 

 A large specimen of the present species, even e.xceeding the Atjeh-specimen of de Man, was 

 caught by the "Siboga" and distinctly demonstrates, that Pt. affinis is a valid species, for 

 the width of the exognath of the external maxilliped is only slightly more than that of the 

 ischium and much less than in Pt. spinicarpus. Besides, in de Man's species the tooth at the 

 inner angle of the w-rist of the cheliped is proportionally shorter and somewhat falciform, and the 

 horizontal line near the under border of the palm is much more distinct. 



l) Zool. Jahrb., Syst., Bd 9, 1895, p. 93. 

 'S) Measured under microscope. 



91 



