220 11. CxRAHAM CANNON 



the chitinons cuticle, but, however, they are connected with 

 the gland-cells of the distal group and loosely fill the anterior 

 part of the large labrum. The distal group is represented by 

 three pairs of gland-cells — two placed laterally and one medially 

 — slightly nearer the tip of the labrum. The nuclei of these 

 cells are very large but not cup-shaped. In each pair of cells 

 is a secretion reservoir which opens into the lumen of a very 

 conspicuous duct-cell just as in S i m o c e p h a 1 u s v e t u 1 u s . 



On the Manner oi- Feeding. 



Simocephalus vetulus feeds on small particles and 

 planktonic organisms contained in a current of water which 

 it maintains over its mouth appendages. In observing the 

 animal it is usually on its back as figured in Text-fig. 1, but in 

 describing the method of feeding, to avoid confusi(m, the animal 

 will be assumed to be dorsal side uppermost . 



The valves of the carapace form an incomplete tube about 

 the posterior part of the animal, this tube being effectively 

 completed by the hairs along the ventral edges of the carapace 

 (Text-fig. 1). Posteriorly the tube is open to the exterior and 

 anteriorly it expands at each side of the labrum into the bays 

 from which arise the second antennae. Further, this tube is 

 incompletely divided into a dorso-lateral chamlier, which 

 includes the brood-pouch and in which are the branchiae, 

 and a median ventral food passage. The latter is bounded 

 dorsally by a well-marked food groove (PI. 9, figs. 0. 7, and 8) 

 which runs along the ventral side of the trunk. Ventral to 

 it are the hairs along the edges of the carapace while laterally 

 are the trunk limbs. The current of water carrying the food 

 passes in at the leases of the second antenna, and so passes 

 close to the first antemia on which are situated, according to 

 Scourfield (17), the supposed olfactory organs, and passes 

 out at the postero-Aentral angle of the carapace in the neigh- 

 bourhood of the anus. 



The appendages chiefly responsible for maintaining the food- 

 stream are the first, third, and fourth trunk-limbs. Caiman (2) 

 states that the third and fourth pairs of trunk-limbs ' are 



