282 ZOOLOGY 



This is not a large group, and its relation to the other 

 Thoracostraca is the subject of much difference of opinion. 

 The best-known genera are Biastylis ( = Guma) and Zeucon. 

 Among the points of interest presented by these animals are 

 the following : — the second antennae, rudimentary in the 

 female, are in the male as long as the body, a sexual dis- 

 tinction which exists also in Nebalia. The mandible is with- 

 out a palp, as in the PhyUopoda. There are only one pair of 

 gills, which are of large size, and are borne by the second pair 

 of maxillipedes. The two eyes lie close together, or have fused 

 into a single mass, which, contrary to the usual rule in the 

 Thoracostraca, is sessile. The brood-pouch, in which the eggs 

 undergo their developement, is formed from processes, probably 

 epipodites, of the fourth, fifth, and sixth thoracic legs, an 

 arrangement which is also met with in the Schizopoda and 

 the Arthrostraca. 



Little is known about the habits of these animals ; they 

 live together, usually on a sandy bottom, at considerable depths, 

 they rest during the day and come to the surface and move 

 about at night. 



Sub-order 2. STOMATOPODA. 



Chaeactekistics. — The carapace is short, and leaves a variable 

 number of thoracic segments free. Portions of the head bear- 

 ing the eyes and antennae are also free and moveable. There 

 are five pairs of maxillipedes, and three pairs of biramous 

 thoracic feet. The abdomen is large, and the abdominal 

 appendages carry the gills. 



The Stomatopoda are animals of considerable size, the 

 larger species of Squilla attaining a length of 7 or 8 inches or 

 more. The carapace is short, and does not cover the three 

 thoracic segments which bear legs ; the five segments in front 

 of these, which carry the five pairs of maxillipedes, are 

 much shortened. The portion of the head bearing the eyes, 

 and that carrying the antennae, are free and moveable, and- the 

 ventral portions of the segments covered by the carapace are 

 also capable of a certain amount of movement upon one another. 

 The six abdominal segments are large, and end in a broad telson. 

 The iirst antenna consists of a basal shaft bearing three long 



