148 



Part III. — Twenty -third Annual Report 



our shores. Figure 20 in plate x. shows one of the fifth pair of thoracic 

 feet of a female specimen. 



Fam. Asterocherid^e. 

 Genus Dyspontius, Thorell (1859). 



Dyspontius curticaudatus, sp. n. PI. xiii., figs. 1-10. 



Description of the Female. — Length 'Smm. (about ^ T of an inch) ; 

 somewhat similar to Dyspontius striatus in general appearance, but con- 

 siderably smaller, except that the abdomen is also distinctly shorter, and 

 the cephalosome rather more distinctly triangular in front. The 

 abdomen and furcal joints are very short, and are together scarcely longer 

 than the combined lengths of the preceding segments of the metasome 

 (%• !)■ 



The antennules are short, moderately stout, sparingly setiferous, and 

 composed of eight joints ; second and last joints subequal and longer 

 than any of the others ; the fourth is short, being only about half the 

 length of the joint on either side, as shown in the annexed formula : — 



Proportional lengths of the joints, 14 ■ 25 - 10 • 5 • 10 • 8 • 10 • 23 

 Numbers of the joints, - - -1 2345678 



A short sensory filament springs from about the middle of the end joint 

 (fig- 2). 



The antennas (posterior antennas) are moderately elongated, four- 

 jointed, and armed with three moderately stout terminal spines, the 

 middle one being considerably elongated and the outer very small ; the 

 outer ramus is rudimentary (fig. 3). The siphon reaches to about the end 

 of the cephalosome. 



The mandibles are very slender, and a small portion of the distal end 

 of the inner margin is coarsely dentate, as shown in the drawing (fig. 4). 



The maxillae are somewhat similar to those of Dyspontius striatus, 

 but are rather stouter, and the inner ramus is proportionally scarcely so 

 elongate, being only slightly longer than the outer ramus ; the terminal 

 setae of the outer and inner rami are also similar to those of that species 

 (fig. 5). 



The first maxillipeds resemble those of Dyspontius fringella, Giesb., 

 very closely ; they are furnished with a small fringe of setae near the end 

 of the second joint ; the terminal claw is moderately short (fig. 6). 



The second maxillipeds have the second joint elongated, but the third 

 and fourth, which are subequal in length, are together not much more 

 than half the length of the second joint ; the terminal claw is stout and 

 moderately short, and about equal to the combined lengths of the two 

 preceding joints (fig. 7). 



The swimming feet resemble those of Dyspontius striatus. In the first 

 pair neither of the two branches bear terminal spines ; the first joint of 

 the outer branch, which is nearly twice as long as the next, carries a short 

 seta on the distal angle of the outer margin, and another on the lower 

 half of the inner margin ; the second joint bears a short spine on the outer 

 angle and a seta on the inner margin, while the last joint is furnished 

 with two small spines on the outer margin, two setae on the inner margin 

 and two more setae at the apex ; the first joint of the inner branches bears 

 one and the second two setae on their inner margin, while the third carries 

 three on the inner margin, one small seta on the outer margin, and two of 

 moderate length at the apex, as shown in the drawing (fig. 8) ; the second 

 pair, which were somewhat similar to the third, were damaged and no 



