66 



CARL BOVALLIUS, AMPHIPODA HYPERIIDEA. I. 



MIMONECTID^E. 



2. MIMONECTES SPHjERICUS, C. BOVALLIUS, 1885. 



PL VI, fig. 1—10. 



Diagn. Caput dimidium diametri sphasrse altitudine non aequans. Articulus primus flagelli antennarum 

 primi paris pedunculo plus quam quater longior, angustus, serratus. Segmenta sex prima 

 percei sphaeram formantia. Metacarpi pedum percei primi et secundi parium prominentia 

 spinulosa instructi, non hirsuti. Pedes tertii paris sextam partem diametri sphaerae longi- 

 tudine haud aequantes. Telson pedunculo pedum uri ultimi paris angustius, sed dimidio pe- 

 duneuli longius. 



The head is not half as high as the diameter of the globe. The first joint of the flagellum 

 of the first pair of antennce is more than four times as long as the peduncle, narrow, 

 serrated. The first six segments of the perceon form the globe. The metacarpi of the first 

 two pairs of perceopoda are provided with a spinulous prominence, not hirsute. The third 

 pair equal a sixth of the diameter of the globe. The telson is narrower than the peduncle 

 of the last pair of uropoda, but longer than half the peduncle. 



Colour. Whitish, with some few minute red spots on the lower parts of the perasonal segments, 

 pellucid. 



Length. 12 — 16 mm. 



Diameter of the globe. 9—14 mm. 



Hal). The Northern temperate and the tropical regions of the Atlantic (D. M.). 



Syn. 1885. Mimonectes sphcericus, C. BOVALLIUS. 



"Mimonectes, a remarkable genus of Amphipoda 

 Hyperidea», p- 11, pi- 2, fig. 12. Nova Acta 

 Soc. Reg. Scient. Upsal. Ser. III. Vol. 13. 

 1887 . »Systematical list of the Amphipoda Hyperiidea». 

 Bih. t. K. Sv. Vet. Ak. Handl. Bd. 11. 

 N:o 16, p. 15. 



In Mimonectes sphsericus the sphserical portion of the body is comparatively 

 larger than in the preceding species, one segment more of the pereeon participating in 

 its formation. If there were not any other characteristics to distinguish the species than this 

 greater or smaller development of the globe, it might seem probable that it depended only 

 upon variation owing to age or sexe, but, as will be seen from the following description, 

 there are many and good specific characteristics, better perhaps than in most of the ge- 



joint in question never has more than one such spine, while in the Gammarina the number varies. The object 

 served by these spines is no doubt similar to that of the coupling-spines. One arm of the cleft apex has a sub- 

 terminal expansion, and the other arm is internally roughened or serrulate. By these contrivances a pair of the 

 spines lying crosswise helps to keep together the branches of the pair of pleopods, and so to add force to the 

 swimming-stroke. But these spines with cleft terminations have plumose shafts, and are evidently plumose setae 

 modified for a special purpose. Indeed, in some species, in which the pairs of cleft spines are numerous, some 

 of them show a gradational form of combining the flexibility of the seta with the cleft termination of the spine». 



