458 University of California Publications in Zoology [Vol.22 



fig. 9 ) are small and inconspicuous, but quite distinct, while the 

 ventral ones (v. I. p.) are reduced to slightly raised, ciliated patches 

 on the sides of the foot. The under sides of the dorsal palps are also 

 ciliated. The labial palps of other lamellibranchs are a part of the 

 mechanism for bringing plankton, which serves as food, to the mouth. 

 and this function is retained in Teredo. 



Kellogg (1915) has made a careful study of the ciliary mechanism 

 for the capture and transportation of food in some thirty-six species 

 of bivalves. Xo such investigation has been made for Teredo, but a 

 few preliminary observations on the species we are studying indicate 

 that a similar apparatus is present. Foreign particles touching any 

 part of the body wall, mantle, or gills are immediately entangled in 

 mucus secreted by the epithelium. Anything falling on the gills is 

 quickly carried by cilia to the nearest branchial groove (b. g., pi. 22, 

 fig. 1). The gills extend only a little way forward on the sides of the 

 visceral sac. but the branchial grooves continue to the labial palps 

 (b. g., pi. 22. figs. 2-5; pi. 24, figs. 9-13), and their cilia bear material 

 rapidly forward to be taken into the mouth. This function was sug- 

 gest id by Sigerfoos (190S), though he was mistaken in supposing that 

 the cilia on the mantle also a.ssisted. as will be explained below. The 

 cilia on the few gill bars at the anterior end of the body, the anterior 

 gills [a. g., pi. 24, fig. 9), beat toward the groove. Unlike the more 

 generalized lamellibranchs, cilia do not cover the visceral sac and the 

 interior of the mantle, but are restricted to a narrow strip on the 

 mantle opposite the branchial groove (c/., pi. 22, figs. 2-5; pi. 24. 

 figs. 10-13). Here, particles entangled in mucus are borne rapidly 

 toward the posterior end of the infrabranchial cavity. If the branchial 

 groove is carrying forward more than a very small amount of material 

 it is, without doubt, caught away and carried back by these cilia. 

 Here we have a mechanism which determines on the basis of quantity, 

 and not of quality, whether or not matter taken from the water shall 

 reach the mouth. This is in accord with Kellogg 's findings in all the 

 forms he studied, and is a clue to the analysis of the role of turbidity 

 in the ecology of this borer. 



The palps of this species of Teredo are so reduced that it is doubtful 

 if they exercise much, if any, control over the stream of plankton and 

 other material from the water. Particles falling on the non-ciliated 

 surface of the mantle or body are drawn into a ciliary current by the 

 strands of mucus that are secreted. Material that is carried posteriorly 

 by the cilia on the mantle is expelled from the pallia] cavity. The 



