FROM THE INLAND SEA OF JAPAN. 399 



comparatively shorter than in de Ilaan's adult female ; the median spine on the intestinal 

 region is jnst as long as the two spines on the posterior border, viz. 1'3 mm., measuring 

 a little more than one-third the lateral spines, but the posterior two on the branchial 

 region ai-e, in this specimen, the shortest of all, measuring 0-9 mm. The posterior 

 branchial spines are a little farther, viz. 7'3 mm., distant from the tips of the lateral 

 spines than from that (5'76 mm.) of the median spine. The front and the depression 

 between it and the gastric region are tomentose ; the spines are also granular. In the 

 Leyden type the front is a little less prominent and its lateral margins run somewhat 

 more obliquely than in this female ; but in the other specimens the obliquity is nearly 

 the same. The chelipeds are equal, 37 mm. long, more than twice the length of the 

 carapace (posterior spine included) ; they agree with the quoted description of Arc. 

 septemspinosa and with the fig. 4, pi. 25, in Cuvier's ' Atlas du Regne Animal.' The 

 slender fingers are one-fourth longer than the tapering hand, but carpus and palm 

 appear also finely granulated under a lens. The merojiodites of the ambulatory legs are 

 finely granular, but the following joints seem to be smooth. 



In the other female the five posterior spines are of equal length, but the two males 

 agree with the larger female. In these specimens the whole upper surface of the 

 carapace is slightly pubescent. 



Tlie abdomen of the male (PI. 31. fig. 9) consists of five pieces ; the penultimate seg- 

 ment is once and a half as long as broad and once and a half as long as the terminal piece. 



Measurements in millimetres. 



1. 

 ?• 



Breadth of the carapace, the lateral spines included 33 



Length of the carapace, the posterior spine included 2r75 



Breadth of the carapace, exclusive of the lateral spines... 21 "5 

 Length of the carapace, exclusive of the posterior spine . 30-5 



No. 1. Leyden type of Iphis heptacantha, de Haau; Nos. 2-5. Inland Sea of Japan. 



Whether this species differs from Arc. septemspinosa (Fabr.), Leach, by other characters 

 than the shorter spines, is difiicult to say, because I was unable to compare it with 

 specimens of the latter. I will, however, observe that at the end of his quoted descrip- 

 tion of Arc. septemspinosa, Dr. Alcock adds :— " Of ninety-two specimens in the Indian 

 Museum the lateral spines are found to vary a good deal in length : they are usually, in 

 adults, about as long as the arm, and sometimes a good deal longer ; but in the young 

 they are usually much shorter than the arm." 



Perhaps A^^c. heptacantha is related to Arc. septemsjnnosa (Pabr.), war. gracilis, Hend., 

 from the Gulf of Martaban, but it is difiicult to decide, because his description is too 

 short (Henderson, in Trans. Linn. Soc, ser. 2, Zool. vol. v. 1893, p. 403). 



Arc. quimjuespinosa, "VV.-Mason (111. Zool. 'Investigator,' Crust, pi. 21. fig. G), is 

 certainly a dilTerent species. 



