202 COPEPODA 



which it agrees in a few features, on account of its size and the spinous lamina along the outer margin 

 of the second basipodite of the third foot. 



Scaphocalanus globiceps, obtusifrons, validus and robustus seem to be nearly related, and are, without 

 detailed investigation rather difficult to distinguish from each other. In contrast to Scott, who refers 

 them to Scolecithricella, \ follow Sars, and regard them as more nearly related to Scaphocalanus mag- 

 nus, with which they agree by the number of segments in the anteunulae, by the appendages of the 

 maxillae, and by the structure of the fifth foot in the male. About the differences between S. robustns 

 and globiceps I refer to the former species. The female of S. globiceps is characterised by slender shape 

 comparatively short antennulae, which have a single setae in segment 10 and a Spr. in segment 17. 

 Se Re I pes I is long and slender, and Se Ri I pes II is short and clumsy. St. Re III pes II has 

 about 20 well separated teeth. The inner terminal seta of the anterior surface of Basp. Ill pes III IV 

 is only poorly developed. The second basipodite of the third pair of legs has, laterally, a spinous lamina. 



64. Scaphocalanus robustus Th. Scott. 

 (PI. VII figs 12 a c; text-figs 64 a c). 



1894. Amallophora robusta n. sp. Th. Scott, pp. 56 57, pi IV 1896. Scolecithrix robusta Th. Scott. Giesbrecht&Schmeil, p. 47. 



figs 2426. 1908. I'arran, p. 57, pi. VI fig. 3. 



Description. f.. Size of specimen from Thor St. 167 was 278111111.; anterior division 2-12 mm.; 

 urosome 0-66 mm. Scott's specimen measured 3111111. and Farran's 2-65 3-1 mm. 



The rostrum has rather short filaments (text-fig. 64 a). The head is distinctly raised, and the 

 body is rather robust; the first thoracic somite is fused with the head, and the fourth and fifth thoracic 

 somites with each other; the lateral corners are slightly produced and rounded. The genital somite 

 is only slightly produced below; the receptacnlum seminis is elongated and slender, but rather short 

 (text-fig. 64 b). The comparative length of the abdominal somites and the furcal branches is 33, 20, 18 

 10 and 14; the genital somite is almost as wide and deep as long, and the furcal rami are a little longer 

 than wide. The serration along the hinder margin of somites 2 4 is well developed. 



The antennulae extend to the end of the genital somite; the limitation between segments 24 

 and 25 is rather indistinct; the appendages are like those of S. globiceps, with a single seta in segment 

 10, and 2 in segment 17. The measurements are similar to those of the preceding species; the segments 

 19 and 16 are almost of equal length, and 1-3 as long as segments 80^9, which are, again, a little shorter 

 than segment 15. The antennae, mandibulae, maxillulac and maxillipeds are like those found in S. 

 globiceps. The maxillae possess 4 amalliform and 4 vermiform sensory appendages. 



When the natatory legs sitting on the animal are examined from the side, a curious difference 

 is found between the 3 first pairs and the fourth pair of legs in the basipodites as in related species; 

 the posterior surface of the three first pairs is seen to be excavated, while that of the fourth pair 

 appears cylindric, and in lateral view is almost twice as deep as that of the third foot. The first foot 

 is very much like that of S. globiceps, but the Se Re I scarcely extends to the end of Re II (text-fig. 

 64 c). The second foot has the outer-edge spine of the first outer segment long and sickle-shaped, and 

 the outer-edge spine of the first inner segment short and rounded; the St has 30 short, well separated 



