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The specimen 130. F., although from the same locality as 139. D., appears to belong 

 to a different species; and I am not even sure that it is a Mimosella. The preparation is 

 unfortunately not good enough to allow its characters to be described satisfactorily. The zooecia 

 are shorter than in the other specimens; and their bases do not appear to have the Mintosella- 

 structure. The mode of branching is similar, though fewer internodes are present. Among the 

 ordinary zooecia are smaller spindle-shaped structures containing a deeply stained mass, which 

 appears to consist of a number of longitudinally arranged fibres. I am unable to decide what 

 is the nature of these structures. 



I think there can be no doubt that the specimens 139. D. and 39. C. are very closely 

 allied to the species described by Heller, Hincks and Joliet, as given in the synonymy at 

 the commencement of the present account. The balance of evidence seems to be in favour cf 

 the view that the 'Siboga' specimens belong to Heller's species. 



Heller's account was based on material collected on the Adriatic coast, and preserved 

 in the Triest Museum. The specimens had been labelled by Mexeghixi as Cuscutaria verticillata ; 

 but this appears to have been merely a MS. name until it was recorded by Heller. The 

 original account specially mentions the fact that the zooecia commonly originate "paarig (3 — 4 

 Paare) von einem Puncte"; a description with which my own observations well agree. Hixcks, 

 some years later, recognised Heller's species from his own Adriatic material. He expressly 

 comments on the narrow, jointed base of the zooecia : — a feature which had previously been 

 described by Joliet: — but he describes the "ventral" face of the zooecia as being almost 

 entirely occupied by a membranous "area"; justifying the reference of the species to Hippuraria 

 and to the Fam. Triticellidae. If an "area" really occurs in Adriatic specimens the 'Siboga' 

 form probably does not belong to the same species. I think, however, that it is justifiable to 

 feel some doubt with regard to the correctness of this part of Hixcks's description ; partly 

 because Joliet has recorded nothing of the kind in what appears to be the same species; and 

 partly because no information is given as to the way in which Hixcks' specimens had been 

 prepared. Unless special precautions are taken in mounting, Ctenostomes of this type become 

 tnuch shrivelled in the process; and the appearance of a membranous area may have been 

 due to artificial contraction. But in any case I feel justified, after examining Busk's type-specimen 

 of Hippuraria egertoni l ) preserved in the British Museum in expressing the opinion that Hixcks' 

 specimens had nothing to do with the form described by Busk. In both the accounts which 

 have been given by Joliet, that author refers to the narrow peduncle on which the zooecia 

 execute movements of "nutation". He further describes the muscles by which these movements 

 are effected and regards them as modified parietal muscles ; and in his later account he describes 

 their origin from a diaphragm separating the zooecium from its peduncle in a way with which 

 my own observations agree exactly. There is thus considerable reason for believing that both 

 the Adriatic specimens and those from Roscoff described by Joliet are referable to Mimosella. 

 If the 'Siboga' specimens are rightly referred to the same species the distribution of this form 

 must be a wide one. 



1) See below, under Triticella boeckii. 



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