SYSTEMATIC AND BIOLOGICAL ACCOUNT 143 



anomala ; (5) Abylopsoides ventralis; (6) Abylopsoides dorsalis; (7) Abylopsoides basalis;(8) Pseudabylopsis 

 anomala. 



Judging by figures all the specimens so named belong to species of Abyla, Ceratocymba or Abylopsis 

 whose development has been abnormal. I have come across such specimens very occasionally myself. 

 They will be of interest to those who study organogeny, but I feel that it was unnecessarily confusing 

 to give them new specific and generic names. 



From what little attention I have been able to devote to their analysis I am inclined to believe that, 

 for instance, in Pseudocymba asymmetrica (Sears's text-figs. 23 D, E) the sagittal area of the anterior 

 nectophore has been suppressed, and that there has been an overgrowth of one of the sides bordering 

 on it; and that in Pseudabyla dubia (Sears's text-fig. 17F) one of the margins of the dorsal facet has been 

 suppressed. But we have no knowledge, at present, of what organizers may have been upset during 

 the ontogeny of the specimens. In my opinion if the specimens represented new species, we should 

 find in anterior nectophores of known species just that sort of constant tendency towards variation 

 which has the functional potentiality that seems to appear in the hydroecial folds of the posterior necto- 

 phores. Also specimens of Abyla spp., Ceratocymba spp. and Abylopsis spp. are very abundant, but 

 these crazy specimens are very rare, and none of them have the appearance of normal healthy speci- 

 mens : it is not their rarity alone that makes me think that they are freaks. I can only record my regret 

 that Dr Sears finally decided to make this abnormal material into the types of new species and genera, 

 since I fear it will cause much confusion amongst systematists. 



Dr Sears has brought together much old and a great deal of new data on Abyline species, but the 

 animals appear to be exceptionally variable, and this is only the starting point of our inquiries. The 

 figures are very clearly drawn, but were not made, I understand, with a camera lucida. Those of 

 anterior nectophores do not perhaps bring out the fact that asymmetry is the rule. My own analysis 

 (p. 144) of the homologies of ridges in posterior nectophores leads me to affirm that in Ceratocymba spp. 

 the dorsal ridge is present, whilst it is absent in Abyla spp. Dr Sears evidently holds the opposite view. 

 For the sake of any systematist who tries to compare Dr Sears's descriptions with my own I should 

 mention that in her very useful figure 5 (p. 14) the following synonyms must be borne in mind: 



Dr Sears's terminology: Terminology of this report: 



Dorsal ridge Left lateral ridge 



Left lateral ridge Right lateral ridge 



Right ventral wing Left ventral wing 



Left ventral wing Right ventral wing 



Right lateral tooth Left lateral tooth 



Abundant material of Abylid eudoxids is available in the Brit. Mus. (Nat. Hist.) Collection. 

 Systematists would be very grateful for a revision which would enable them to identify and relate 

 them with their corresponding polygastric stages. 



Abylinae 

 Abyla 

 The species of Abyla, as that name has been generally used, fall naturally into two groups, which 

 should be given generic status. The chief characteristics of the two groups are as follows : in the species 

 of the Ceratocymba group, namely C. sagittata, C. dentata and C. leuckartii, the eudoxid is a 'cymba', 

 and the posterior nectophore has left and right dorso-lateral ridges terminating on the lateral teeth. 

 There is a short, median-dorsal ridge terminating in the dorsal tooth. In the species of the trigona- 

 group namely Abyla trigona, A. carina, A. haeckeli, A. bicarinata and A. schmidti, the eudoxid, where 

 it is known, is an ' amphiroa' '; and in the posterior nectophore, what appears to be the homologue of 



