294 ZOOLOGY 
Appendages of Asellus. 
1. Antennules. 6. Maxillipedes } thoracic 
2. Antennae. 7-13. Walking legs ae 
3. Mandibles. 14-19. Abdominal legs 
4. 1st maxillae. (only five in the female). 
5. 2nd A 
The appendages are nearly the same as in Amphipods ; there 
are two pairs of antennae, the second being much the larger; both 
are uniramous. The mandibles carry a palp. There are two 
pairs of maxillae and a pair of mavyillipedes, and seven pairs of 
walking thoracic limbs, of which the anterior are directed forward, 
the posterior backward. The most anterior of all are prehensile 
organs, and lie forward against the maxillipedes; they are en- 
larged in the male, and take no part in locomotion. There are 
six pairs of abdominal appendages in the male, and five in the 
vixii =. 
¥ 2 1 wi20 aap Rie Ae ee: Bw 
- ~—fnge S N 
Fic. 170.—Asellus aquaticus. Side view of female. From Leuckart and Nitsche, 
after G. O. Sars. 
I.-VI. The six anterior segments 7-13. The thoracic limbs. 
forming the cephalothorax. 14. Ist abdominal appendages, 
VII.-XIII. The seven free thoracic seg- 16. 3rd abdominal appendages. 
ments. 17. 4th abdominal appendages. 
XIV.-XIX. The six abdominal segments, 18. 5th abdominal appendages. 
partly fused. 19. Last abdominal appendage. 
1. The anterior antennae. 20. Eyes. 
2. The posterior antennae. 21. Heart, with three pairs of stigmata. 
3. The mandible (palp). 22. Ovary and oviduct opening on 
4. The Ist maxilla. base of 5th thoracic limbs. 
5. The 2nd maxilla. 23. Brood-pouch. 
6. The maxillipede. 
female ; im the former the second pair are modified in connection 
with the opening of the genital duct, this pair are absent in the 
female. The three following pairs act as branchiae; the exo- 
podite and endopodite are both squarish, lamelliform structures, 
the former lying over and protecting the latter, which has very 
