647 



posteriorly by a projecting lobe armed with several small spines, which in 

 the male are arranged in 2 successive fascicles, dactylus strong, falciform. 

 Posterior gnathopoda in female with the basal joint very narrow, carpus 

 extremely small, propodos exceedingly large, oblong fusiform in shape, being 

 more than twice as long as it is broad, palm arcuate and minutely denti- 

 culate, being defined behind by two projections, each tipped by 2 spines, hind 

 margin about half the length of the palm, dactylus strong, falciform; posterior 

 gnathopoda in male somewhat larger than in female, with the meral joint produced 

 in front to a conical projection, propodos somewhat arcuate, with the palm hol- 

 lowed, being filled by a membranous tissue, and forming in front an angular 

 projection, dactylus extremely strong and abruptly curved in its outer part. 

 The 2 anterior pairs of pereiopoda in female extremely slender, filiform, with 

 the carpal and propodal joints of equal length, in male comparatively more 

 strongly built, and having the carpal joint shorter and the propodal one 

 somewhat expanded, with 4 strong spines inside. Antepenultimate pair of 

 pereiopoda much smaller than the others and nearly smooth, basal joint 

 occupying half the length of the leg, and connected to the meral joint by 

 an oblique suture, propodal joint simple, slightly widening distally. The 2 

 posterior pairs subequal and rather strong, with the propodal joint subcheli- 

 form, palm armed with 2 spines and defined by a slight projection carrying 

 2 juxtaposed spines, between which the tip of the dactylus admits of being 

 impinged. Uropoda in both sexes of a similar appearance, being narrow 

 cylindrical in form, with the outer joint very small. Body of somewhat 

 variable colour, being generally of a greyish white hue, mottled all over 

 with small brown and red specks, but sometimes exhibiting a uniformly dark 

 red colour. Length of adult female reaching 16 mm., of male 20 mm. 



Remarks. As above stated, this form was first described by Slab- 

 ber under the name here quoted. The Sqtiilla renfricosa of Miiller is the 

 ovigerous female of this species, and also Gammarus pedatns of Abildgaard 

 is unquestionably the same. The 2 forms described by Sp. Bate as Proto 

 pedata and P. Goodsiri, and also maintained by Boeck as distinct species, 

 ought to be united, the former being the female, the latter the adult male 

 of the species here treated of. The Naupredia triatis of v. Beneden would 

 seem to be an immature specimen of the present form, in which, by some 

 accident, the 2 posterior pairs of pereiopoda had been broken off. The species 

 cannot be confounded with any other of the northern Caprellidse. 



Occurrence. - I have met with this form along the whole Norwegian 

 coast, from the Chriatianiafjord to Vads0. It is generally found in compara- 

 tively shallow water among grass, occurring often in great abundance. 

 Occasionally it may also be taken from greater depths, among the red algse, 



