vol. l] Uitter~])avis.— Enteropneusta. 17:! 



about eight miles off Point Loma, the aearest point of main land, 

 in about seventy to one hundred fathoms of water. The observ- 

 ations upon which rest the probabilities here indicated relative to 

 the habitat of the parents, were that the larva' were always obtained 

 much more abundantly over the banks than elsewhere. While 

 the area covered by our collecting operations was not sufficiently 

 extensive to justify the conclusion that they were entirely 

 limited to this small spot, the constant absence of them from 

 towings made in San Diego Bay and the outside waters between 

 the banks and the main land, makes the point we are now chiefly 

 interested in, highly probable, namely, that the parents did not 

 live in the shallow water along shore, but in a depth sufficient 

 to make it necessary for them to rise through a considerable 

 number of fathoms in order to reach the levels at which they 

 were taken; and, of course, to a still greater height in order 

 to reach the surface. The bearings of this will be seen in 

 connection with our study of the ecology of the larva. 



With this as with all other known species of tornaria. we 

 have no information except by inference as to the parent. What 

 relevant facts we have point to Balanoglossus occidentalis Ritter 

 (MS.)* as the parent. Of the three species of enteropneusta 

 known to occur ou the coast of southern California, we are now 

 sure that DolicJtoglossus pusillus Ritter (MS.) cannot be the 

 parent (see the section, p. ■_'()(), on the embryology of that 

 species). Of the other two species, Stereobalanus willeyi Ritter 

 (MS.) seems to be excluded by its possession of two proboscis 

 pores even in the adult, while no trace of a second pore is 

 present even in the larva of the species now under consideration. 



As previously stated, our studies on the morphology of 

 the larva have been prosecuted from the standpoint of ecology. 

 In the larval life of the enteropneusta three periods should be 

 recognized; namely, a period of larval development; a climactic 

 period; and a metamorphic period, i.e., a period of development 

 again, but this time development toward the adult animal. 



*For the benefit of those who have not followed the latest gyrations in tin 

 synonymy of the enteropneusta it may lie stated that the genus Balanoglossus as 

 inn recognized is a part of the genus Ptychodera of Spengel's monograph. 

 Balanoglossus occidentalis is a species rather closely related to, though still clearly 

 distinct from, the well-known It. clavigerus Delle Chiaje of tin- European coasts. 



