UNIVERSITY 



t)F 



1908] Davis. Life-history of Dolichoglossus. 195 



scribed in these words: "Animals do not swim freely, but glide 

 about with proboscis pointed forward over the supporting surface. 

 These movements are made mainly by means of the large cilia 

 composing the posterior ciliated band, although their action ceases 

 occasionally for short periods. At such times the animal con- 

 tinues to move by means of minute cilia with which the body is 

 covered, but the motion is very slow." Ritter-Davis '04, pp. 

 201-202. This is correct for the first phase of period III. As 

 the larva grows older there is less and less use of the ciliary band 

 until finally it is not used at all; at least there is no more rapid 

 creeping. 



During the latter part of the first phase of period III, at times 

 when the ciliary band is not in use, considerable muscular activity 

 may be noticed in the proboscis, this member now contracting and 

 extending alternately. These movements are characteristic of 

 the second part of period III. By them, and also through the 

 action of the small body-cilia, the animal is able to creep slowly 

 about over the supporting surface. Bits of sand and other sedi- 

 ment readily adhere to the body in the region of the collar, 

 collected there by the mucus or slime w r hich is actively secreted 

 at this time. The secretion in one instance was so much that 

 two larvae that happened to meet were bound together, and so 

 closely that neither could escape by its own efforts. In older 

 stages the accumulation of sediment was so great as to necessitate 

 its removal before the animals could be studied. 



It is at this time that the larva begins to burrow. When 

 placed in a dish of mud it soon disappears beneath the surface. 

 The burrowing movements of D. pusillus are very similar to those 

 of the larva described by Morgan '94, p. 17. He says: "It 

 was very noticeable that so soon as the proboscis was thrust in 

 the sand a thick mucus was thrown out from the surface of the 

 proboscis and collar region to which the sand granules stick, 

 forming an irregular tube around the animal. ' ' 



Periods of development correlated with habits and distribution 



of adults. 



The adult life of D. pusillus is passed in burrows in the mud. 

 The animal does not, as many sand-dwelling animals do, come to 



