15 



which is somewhat shorter and more slender than the proximal, is strongly curved with the 

 convexity downwards and the end acute. Second joint is thick at the base and tapers to the 

 end ; its upper margin has about twelve thick setse, the few proximal of them moderately short, 

 while the others are quite short and towards the end extremely short, more similar to teeth 

 than to setae; third joint is moderately thick, expanded upwards from base to end; the other 

 joints are slender. 



The petasma is very different from those in the preceding species, but so similar to that 

 in the following form, S. fulgens, that the outline of the organ in the last-named species (fig. be) 

 is deemed sufficient for conveying a general idea, while the distal half of pars media in S. 

 Challengeri is shown from behind (fig. 4/) and from in front (fig. \g). Lamina externa {la. in 

 fig. be) is considerably shorter than processus uncifer (/«-), with the outer margin angular 

 beyond the middle, its proximal part concave and the distal part a little convex; processus 

 uncifer is somewhat slender, with its most distal part a little or not widened on the inner side 

 (fig. \h). Processus basalis is somewhat slender, a little curved, distally subacuminate and acute. 

 Pars media is somewhat robust. Processus ventralis {pv. in figs. 4/ — 4^) is of middle length, 

 moderately thick at the base, from which it tapers nearly gradually to the acute end, and its 

 distal part is curved much outwards. Lobus armatus (/«.) is long and thick; it has an extremely 

 large hook on the inner side somewhat from the end, which is cut off and has a large hook, 

 while about nine hooks, the six distal moderately large, the others small, are seen as a very 

 oblong group on the posterior side near the outer margin. Lobus connectens [Jc.) is scarcely 

 half as long as lobus armatus, very thick and besides much expanded towards the end, which 

 has a long terminal margin rather deeply excavated somewhat nearer its inner than its outer 

 end, so that the most distal part of the lobe is divided into two short and thick secondary 

 lobes, the outer considerably thicker than the inner; the distal margin of the inner secondary 

 lobe has three large hooks, the distal and outer margin of the outer lobe has about seven 

 smaller hooks, and besides the entire lobe has on the front side (fig. 4/) a median longitudinal 

 row of hooks and about three hooks towards the outer margin somewhat before the end. Lobus 

 terminahs (/A), which is almost as long as lobus armatus, is very peculiar and without hooks; 

 its proximal part is directed essentially inwards, and then it suddenly is bent, directed forwards 

 and distally curved outwards; its distal end is in the specimen figured deeply concave with each 

 lateral corner produced into a triangular, acute process, but this end varies much individually, 

 as sometimes only one produced and acute lateral angle is found, sometimes the end is feebly 

 emarginate and generally it is rounded (as in 5. fulgcns, fig. 6/). Where the subproximal bend 

 is found on the lobe, the angle protrudes less or more, and from comparison with the organ 

 in S. splendens n. sp. (Atlantic) I am induced to think that this protruding part is a quite 

 rudimentary lobus inermis. Finally we find on the front side of pars media (fig. 4<,'-) near the 

 origin of processus ventralis two lobi accessorii [lac>j, the outer slender and rather long with 

 a large hook on the end, the inner lobe scarcely half as long but much thicker than the other, 

 with about six hooks on its anterior side. 



Length of a large adult male 31.5 mm., of a large female 35 mm. 



b. Younger Stages. — One of the smallest specimens with black eyes is scarcely 



