No. 3.] GROWTH AND METAMORPHOSIS OF TORN ART A. 437 



pores, presumably a case of atavism). Spengel shows clearly 

 that the proboscis vesicle (so-called heart) does not contain 

 blood and is completely closed on all sides. The connection 

 between the anterior blood sinus (of the proboscis) and the 

 blood-vessels of the trunk is shown. The collar pores arise as 

 evaginations from the first gill slits and connect secondarily with 

 the cavity of the collar. The nervous system of the adult is 

 described, and it is stated that it arises as an ectodermal invagi- 

 nation in the collar region of the embryo. The reproductive 

 gonads open by a series of small pores to the exterior. 



M. A. F. Marion described two new species of Balanoglossus 

 in 1886, but did not enter into any discussion as to the position 

 of the animals. Also R. Koehler published a paper in 1886 on 

 the anatomy of another new species, and later (July, 1886) he 

 published a short paper on the ancestry of Balanoglossus. He 

 rejects any affinity with the Echinoderms and follows Bateson 

 in the belief of a Chordate relationship, but believes a more 

 precise opinion may be given as to the systematic position of 

 Balanoglossus than Bateson expressed. Balanoglossus is degen- 

 erate, and its larval form has adapted itself secondarily to the 

 same conditions as the larva of the Echinoderms ; hence its 

 outward similarity. The ancestry of the Chordata goes back 

 to the Worms (probably to the Chastopoda). Balanoglossus 

 branched off from the main stem before the earliest Chordate 

 arose. Later another degenerate branch arose represented by 

 the degenerate series Cyclostomes, Amphioxus, and Tunicates. 

 Haldeman described also in this year a species of Tornaria 

 found at Beaufort, N.C. (U.S.A.) It differs from the New Eng- 

 land Tornaria, and is in many respects like that described by 

 Metschnikoff. 



Weldon, in 1887, published a preliminary note on two new 

 species of Tornaria from the Bahamas. The Nassau larva is the 

 same that is described in the preceding section, where a longer 

 reference is made to the discovery. 



In 1888, Schimkewitsch published a short paper on a new 

 species of Balanoglossus. He suggests that the pulsating 

 vesicle of Tornaria may prove homologous to the pulsating 

 vesicle of the Molluscan larva. The cavities of the paired 

 enteroccels are homologous with the cavities of the muscle 

 plate of the vertebrate embryo. The generative organs have 



