628 ARTHUR WILLEY. 



4. Synapticula. — By preparing out a piece of the wall of 

 the branchial sac I became aware of the presence of synap- 

 ticula in Spengelia before seeing them in section (fig. 3). 



5. Gonads and Genital Ducts. — In the branchial region 

 gonads occur both medially and laterally, that is on each side 

 of the branchial groove (fig. 2). Their ducts open at the lips 

 of the latter. In the post-branchial region where the dermal 

 pits occur, the genital pores are numerous, and are not confined 

 to the submedian line, so that several genital pores may be 

 seen in one section. Some genital pores open into the dermal 

 pits, while others open directly to the exterior near the dorso- 

 lateral margins of the body. But in Spengelia, contrary to 

 what obtains in other Enteropneusta (with exception of 

 Balanoglossus canadensis and of the mediad accessory 

 pores of Schizocardium brasiliense), the accessory genital 

 ducts and pores do not perforate the longitudinal musculature. 

 In the post-branchial region of Spengelia there is a very wide 

 interval between tlie dorsal longitudinal muscles and the 

 veutro-lateral longitudinal muscles, and all the genital pores 

 occur in this interval. 



6. Miscellaneous. — With regurd to other points, it is 

 only necessary to mention here that Spengelia agrees with 

 Schizocardium and Glandiceps in having an unpaired asym- 

 metrical proboscis-pore. The canal (Eichelpforte) leading to 

 the pore swells out into a large vesicle before discharging to 

 the exterior, and at the base of the vesicle there are muscle- 

 fibres presenting the appearance of a sphincter muscle. 



Spengelia further agrees with Glandiceps in the massive 

 development of chondroid tissue in the neck of the proboscis 

 and in the length of the posterior cornua of the proboscis 

 skeleton. 



In the preserved condition the gill-pores were clearly visible 

 at the base of the branchial grooves, as they are in Glandi- 

 ceps talaboti. 



7. Summary. — If it were not for the presence of vestigial 

 roots in the collar nerve-cord, Spengelia (apart from its 

 own peculiar features, e. g. dermal pits, splanchnic layer of 



