St. Andrews Marine Laboratory. 41 



These bands are somewhat regularly folded or tabulated at 

 the margin, and have a pale grey or dull whitish colour. 

 The elements (probably male) were not much developed, the 

 minute constituent cells being finely granular. The bands 

 met in the centre of the disk, so that there was little room 

 for doubt in regard to the absence of manubrium and mouth. 

 A similar condition to the foregoing was observed in Tima 

 Bairdii, Johnst., one of those characteristic forms found long 

 ago by Edward Forbes on the West Sands at St. Andrews, 

 a locality which the pen and pencil of this genial naturalist 

 would alone have made classic ground to the marine 

 zoologist. 



In the midwater-net of the 28th September a small example 

 of Tima Bairdii measuring about f inch across (PL VIII. 

 fig. 2) presented an unusually flattened shape, from the absence 

 of the large manubrium. Moreover, the radial canals, 

 r c, with the reproductive bands, which had a minutely 

 granular structure, closely approached each other in the centre 

 of the disk, so that a small circular area only intervened. 

 Careful investigation of the latter area showed that the hyaline 

 ectoderm of the Medusa was continuous in this region, so that 

 no trace of an aperture existed. The radial canals ceased at 

 the margin of the area, one or two, indeed, having a slight 

 expansion before terminating. This area, although solid, 

 corresponded with the gastric region in connexion with the 

 radial canals, and therefore in this respect differed from the 

 preceding examples of Thaumantias. 



In the case just narrated (Tima Bairdii) the specimen had 

 by no means reached the average size of the period ; but this 

 need not be held as indicating that it was stunted from the 

 abnormality of its alimentary apparatus. In the large Thau- 

 mantias first mentioned it is apparent that without a trace of 

 manubrium or mouth the species had not only attained the 

 ordinary limit of growth, but had largely exceeded it. So far 

 as our experience goes, no other Thaumantias in British 

 waters attains such dimensions, though the digestive appa- 

 ratus exists in full perfection. The instance of the Thau- 

 mantias therefore is more remarkable than Mereschkowsky's, 

 tor in his small species (Bougainvillia) the abnormal speci- 

 mens were " only a little exceeded in size by the normal adult 

 individuals," that is to say, those without manubrium and 

 mouth were somewhat less. 



In his " Remarks on a Mode of Nutrition among the Hydro- 

 medusa? of the Russian seas " C. Mereschkowsky * gives an 



* Ann. & -Mag. Nat. Hist. ser. 5, vol. iii. pp. 177-181, pi. xx. (1879). 



