12 W. T. CALM AN. 



notices the early appearance of ova in the buds in several cases 

 (e. g. Colella), and Hjort (1. c, pp. 604 and 605) has recently 

 called attention to the migration of the egg-cells from the 

 parent animal into developing buds in the case of Botryllus. 

 It is possible that we have here to do with an instance of such 

 migration, but on the other hand, if the buds arise, as seems 

 probable, from the ''vascular processes,^^ it is very difficult to 

 see how the ova could have reached their destination. 



The youngest buds (PI. 1, fig. 6, and PI. 3, fig. 29) consist 

 of a two-layered vesicle, the space between the layers contain- 

 ing loosely scattered cells and one or two ova. Older buds 

 (PI. 1, fig. 5, and PI. 3, fig. 31) show the two peribranchial 

 cavities developed at the sides of the branchial sac. In the 

 latter the endostyle can be seen in sections as a pair of ridges 

 near its anterior end. The neural tube lies dorsally to the 

 branchial sac, but its communication with the latter could not 

 be traced. In sections of the abdominal region (PI. 3, fig. 

 30) the rudiment of the heart is seen in its pericardium, and 

 on either side of the latter are the two " epicardial tubes,'' 

 which, as has been already stated, are in this genus absent or 

 rudimentary in the adult, but which in Fragaroides persist as 

 a great space running the whole length of the body. A long 

 "tail" projecting from the hinder end of the older embryos 

 (PI. 1, fig. 5) is probably the outgrowing vascular process. 



Systematic Position. — The unnamed genus referred to 

 by Professor Herdman as (?) ignotus, and already men- 

 tioned above, is so similar in general appearance as well as 

 in habitat to the form here described that the two must be 

 nearly related, if not identical. The poor state of Professor 

 Herdman's specimens, which accounts for the brevity of his 

 description, may also account for certain discrepancies, as for 

 instance when Professor Herdman describes the tentacles as 

 numerous and equal, and the nerve ganglion as spherical in 

 form. Our species, however, certainly does not belong to the 



Polyclinida3, to which Herdman refers his (?) ignotus 



" from the general appearance of the colony and of the 

 ascidiozooids.'' The genus being certainly nondescript and 



