A SMALL COLLECTION OF AMPHIPODA FROM JUAN FERNANDEZ 83 



Masafuera, »under stones, 500 metres above sea level », S. P. E. No. 

 327. 27. II. 17. Two tubes. 



One tube contains about one dozen specimens, one male, the others appar- 

 ently females. These average about 12 mm. in length. In the other tube 

 there are several specimens, all small, about 4 mm, in length. 



Masatierra, » under stones. » S. P. E. No. 729. 31. VII. 17. 



Several varying in size from 4 mm. in length up to 8 mm. Young speci- 

 mens, none of them having the second gnathopod subchelate and none bearing 

 eggs. 



Masatierra, »among withered leaves. » S. P. E. No. 494. 7. IV. 17. 

 Several varying in size up to 8 mm., none with subchelate second gnatho- 

 pods nor bearing eggs. 



Masatierra, »in a brook. » S. P. E. No. 724. 31. VII. 17. 

 12 specimens, the largest 9 mm., two of them being apparently immature 

 males. 



I have no hesitation in identifying all the specimens named above as 

 belonging to O. chiliensis M.-Edw., a species already known from South 

 America and from New Zealand. In New Zealand it is the commonest of the 

 shore hoppers and is usually found under stones, etc. about high water mark, 

 though under favourable circumstances it may sometimes extend a little 

 distance away from the sea. It is well described by Stebbing in Das Tier- 

 reich, Amphipoda (1906, p. 537), and the fully developed male can generally 

 be easily recognised by the stout second antenna, by the large rounded tooth 

 or lobe near the finger hinge on the palm of the second gnathopod and by 

 the broadening of the meral and carpal joints of the fifth peraeopod and, to 

 a little extent, of the fourth peraeopod. The species was collected at the Juan 

 Fernandez Islands by the Challenger Expedition and both male and female 

 specimens were very fully described and figured by Stebbing under the name 

 O. selkirki. The male examined and figured by him was probably somewhat 

 immature for the fifth peraeopod shows no broadening of the joints, and the 

 second gnathopod has not acquired the final adult form. 



I think there is no doubt that 0. serrulata Dana is a synonym of 0. 

 chiliensis M.-Edw. This is clearly indicated by his figure of the last peraeopod 

 (pi. 58, fig. 7, 1) which shows the broadened carpus usually met with in this 

 species; the figure of the second gnathopod (fig. 7, i) though too small to be 

 of much value, indicates the tooth near the finger hinge with the rest of the 

 palm slightly convex; figure 7, k, showing the serrulate margin of the basal 

 joint of the fifth peraeopod, applies well to 0. chiliensis though the character 

 is possessed by other species also. Moreover Dana's specimens were collected 

 at the » Black Rocks, in the Bay of Islands, New Zealand* where 0. chiliensis 

 is abundant. STEBBING (1906, p. 536) has adopted Dana's name O. serrulata 

 for the species described as O. aiicklaiidiae by SPENCE Bate but that species 

 is well marked in the male by the raised ridges or corrugations on the peraeoif 

 segments, a character which is not found in 0. chiliensis. The second gnatho- 



