no. 1678. ACANTHONISCUS SPINIGER RE DESCRIBED-RICHARD SON. 433 



side, which are nearly three times the length of the segment. Be- 

 tween these two spines are three short ones on the posterior margin, 

 one being in the median line. Anterior to these spines are four 

 small tubercles, two on either side of the median 



line in longitudinal series. Lateral to the 



long 



Pig. 3. — Acanthon- 

 iscus spiniger. 

 Uropod. (Under 

 side.) 



spine, halfway between it and the lateral margin, 

 is one small spine on either side. The six follow- 

 ing segments are about equal in length. Each is 

 armed with two extremely long spines, one on 

 either side of the body. Between these long spines 

 are three small spines on the posterior margin, one 

 in the median line. Anterior to these spines are 

 two small tubercles, one on either side of the 

 median line. Lateral to these 

 spines are two small ones, half- 

 way between them and the lateral margin, one small 

 anterior one and a posterior one, which gradually 

 increases in length, that on the seventh segment 

 being about half as long as the longest spine. 



The first two segments of the abdomen have the 

 lateral parts covered by the last thoracic segment. 

 The lateral parts of the three following segments 

 are greatly produced, the pos- 

 terior angles being acute. These 

 five segments are about equal 

 in length; the third and fourth 

 are armed with two small spines 

 on the posterior margin, one on 

 either side of the median line. 

 The sixth, or terminal segment, 

 is Avidest at the base, contracted 

 about the middle with the posterior half widely 

 rounded and notched in the middle, a small 

 triangular process on either side of the notch. 

 On the anterior portion of the segment are two 

 long spines, equal in length to twice the length 

 of the segment, placed one on either side of the 

 median line. The peduncle of the uropoda re- 

 sembles in form the lateral parts of the third, 

 fourth and fifth thoracic segments; the inner pos- 

 terior angle is acutely produced, the outer angle being rounded. 

 The inner branch is inconspicuous in a dorsal view, being con- 

 cealed beneath the abdomen; it is attached at the inner antero- 

 lateral angle of the peduncle and does not quite reach the tip of 

 Proc. N. M. vol. xxx vi— 09 28 



Fig. 4. — Acanthon 

 is cds spiniger 

 Maxilliped 

 X 27|. 



Fig. 5. — Acanthon- 

 iscus spiniger. 

 Second Maxilla. 

 X 77|. 



