9i 



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

 segment longer than the preceding one. 



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

 of Pt. spinicarpus measured by de Man j ). 



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. maxillipeds. 

 Breadth of exognath of ext. maxillipeds . 



Breadth of base of abdomen 



Breadth of base ) 



Length \ 



Length of terminal segment of abdomen 



Length of meropodite 



Breadth of meropodite 



Length of carpo- -f- propodite 



Length of dactylus 



of penultimate segment of abdomen . 



of penultimate pair of legs 



2. Ptychognathus affinis de Man. ^ 



1895. Ptychognathus affinis de Man. Zool. Jahrb., Syst., Bd 9, p. 97, Bd 10, 1898, pi. 28, f. 21. 



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

 Stat. 179. Kawa Bay, west coast of Ceram. 1 rf. 



1 



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



de Max to presume, that perhaps this species was only a young stage of Pt. spinicarpus, 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 tvvice 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 Ptychognathus is proportionally narrower in young individuals than in the adult ones. 



A large specimen of the present species, even exceeding the Atjeh-specimen of de Max, 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 wrist of the cheliped is proportionally shorter and somewhat falciform, and the 



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



1) Zool. Jahvb., Syst., Bd 9, 1895, p. 93. 



2) Measured under microscope. 



91 



