342 ORDER CHOANO-FLAGELLATA. 



Examples of this specific type have been obtained in considerable abundance 

 both in sea-water from the fish-house at the Zoological Gardens, Regent's Park, 

 during the month of April 1877, and since then in water from the open sea at St. Heliers, 

 Jersey. Propelled by the rapid motion of their flagella, the floating colonies of this 

 species pass through the water with such rapidity that it is difficult to retain them 

 in the field of view when a high power of the microscope is being used, and it is 

 only when naturally at rest, or the animalcules become entangled among sur- 

 rounding substances, that their true structure can be satisfactorily determined. The 

 mode of growth of this type seems to indicate that the moniliform colony is pro- 

 duced by the successive longitudinal fission of the primary individuals, though the 

 process has not yet been directly observed. In the larger colonies the perfect chain 

 of animalcules usually assumes a rounded crescentic outline. The individual zooids 

 appear to possess a more indurated cuticular surface than is met with in any other 

 representative of this group, and up to the present time no trace of a plastic or 

 amoeboid condition has been detected. The contractile vesicles are, as with the 

 more ordinary members of this order, posteriorly located. The remarkable resem- 

 blance that subsists between a colony of this specific form and the portion of a single 

 segment of the collar-bearing zooids of the " ampullaceous sacs " of certain sponge- 

 forms will be made apparent on comparing the illustration given of this species with 

 PL IX. Fig. 2 representing such an isolated fragment of the ampullaceous sac of the 

 spiculeless sponge Halisarca Dujardinii. 



Small colonies of this species, consisting of from two to four laterally united 

 zooids only, have been quite recently, November 1880, detected by the author in 

 sea-water, remitted with living Polyzoa by Mr. Thomas Bolton from the Aston 

 Aquarium, Birmingham. 



Desmarella phalanx, Stein sp. 



Zooids resembling those of Desmarella moniliformis, forming similar 

 floating chain-like colonies, but inhabiting fresh water. 



This species is figured by Stein* under the designation of Codonodesnms phalanx. 

 While its fresh-water habitat renders it probable that the form is specifically distinct 

 from the type last described, there can be no doubt as to their generic identity. 

 Since, however, the title introduced by the author has been already made use of 

 in connection with illustrations and textual reference on two occasions prior to 

 the appearance of Stein's volume, t such previously proposed one necessarily takes 

 the precedence. In one of the chain-like colony-stocks of the present type, figured 

 by Stein, no less than eleven zooids are laterally united, while in another, consisting 

 of eight animalcules, the group is in process of division into two smaller aggregates 

 of four units each. Stein apparently entertains doubts as to whether this species 

 represents a permanent and independent stock-form, he having connected with the 

 generic and specific titles introduced by him a provisional significance only. 



Fam. II. SALPINGCECIDJE, S. K. 



Animalcules secreting and inhabiting independent or socially united 

 protective sheaths or loricae, which are either free-floating or attached, in a 

 sessile manner or through the medium of a distinct pedicle, to aquatic 

 objects ; flagellum single, terminal, encircled laterally by a well-developed 

 membranous collar; contractile vesicles usually two or more in number, 

 posteriorly located ; endoplast subcentral. Inhabiting salt and fresh 

 water. 



* ' Infusionsthiere,' Abth. iii., November 1878. 



t ' Popular Science Review,' April 1878, and ' Ann. Nat. Hist.,' August 1878. 



