182 SUMMARY OF CURRENT RESEARCHES RELATING TO 



"Challenger" Ascidians (Culeolus).* — Dr. W. A. Herdmann 

 forms the genus Culeolus for a series of six new species of pedunculated 

 simple Ascidians, belonging to the family Cynthiidse, and having 

 several anatomical peculiarities distinguishing them from all hitherto 

 described genera. The nearest ally of Cideolus is Boltenia, and these 

 two genera have been placed together as a sub-family, the Bolteninse, 

 characterized as Cynthiidte which have the body pedunculated, the 

 tentacles compound, and the branchial sac with more than four folds 

 on each side. 



Culeolus is distinguished from Boltenia by its remarkable branchial 

 sac, and by the external character that its branchial aj)erture is tri- 

 angular, and its atrial aj)erture bilabiate, while in Boltenia both apertures 

 are four-lobed. The branchial sac is in all respects, except the possession 

 of a certain number of longitudinal folds on each side, the simplest 

 form known among simple Ascidians. It may be described as a simple 

 network, formed by two series of vessels crossing at right angles and 

 communicating at the points of intersection. In its vessels is found 

 an extensively developed system of calcareous spicules of considerable 

 but varying size, often much ramified, and having a very characteristic 

 appearance from their gentle curves and blunt ends. 



One of the species, C. murrayi, is described in detail, anatomical 

 and histological, while the other five are not so fully treated, but the 

 different systems in each are compared with those of the type, and 

 the modifications are pointed out. 



All the species are from upwards of 600 fathoms ; five are from 

 over 1000 fathoms, four from over 1500, and two from upwards of 

 2000 fathoms. They all belong to the abyssal fauna. It is note- 

 worthy that these six species, the only deep water BolteninaB, all 

 belong to one genus, notwithstanding their wide distribution in space, 

 one species being from the North Atlantic, two from the Southern 

 Ocean, one from the South Pacific, one from the North Pacific, and 

 one from the centre of the Pacific Ocean on the equator. 



Embryonic Membranes of the Salpidae.f — Dr. J. Barrois finds 

 that some of the discrepancies between the accounts of Salensky and 

 Todaro, which appeared almost simultaneously, are to be ascribed to 

 the extreme diversity in the developmental history of the members of 

 this group of the Tunicata ; and he is able to speak to the correctness 

 of their accounts of the different forms examined by them. 



The first species now described is Salpa maxima, and we see that 

 much that is true of it is true of other forms also. The appendages 

 are either extra-foetal or embryonic. When the ovum has reached its 

 definite position its follicle has the form of a rounded vesicle, with 

 three thick walls, and is attached to the base of a shallow depression 

 in the wall of the branchial sac ; segmentation is now somewhat 

 advanced. The follicle becomes oval, and the depression becomes 

 converted into a cul-de-sac, which projects considerably into the 

 interior of the respiratory cavity ; in this cul-de-sac the follicle is 



* Proc. Roy. Soc. xxxiii. (1882) pp. 104-6 (1 fig.) (Abstract only), 

 t Journ. Anat. et Phys. (Robiu) xvii. (1881) pp. 455-98 (2 pis.). 



