240 J- Platfair McMukkich, 



The tentacles and disc were thin-walled and tlieir longitiidinal 

 (radial) musculature was moderate and not imbedded in tlie meso- 

 gloea. The brownish tentacles owed their color to pigment granules 

 seated in their endodeon. The stomatodaeum was rather short, 

 extending only about half way through the npper enlarged portion 

 of the column ; its mesogloea was rather thin and it possessed two 

 rather shallow siphonoglyphs. 



The mesenteries were arranged hexamerously in three cycles, 

 of which only the primary one seemed to be perfect, althoiigh the 

 secondaries were almost as broad as the primaries and possessed 

 well developed mnscle pennons. The tertiaries were moderatelj^ 

 broad, but their longitndinal muscles were feeble and tliey possessed no 

 mesenterial filaments. In the upper and lower portions of the 

 column the mesenteries diflfered greatly in appearance ; in the former 

 region (Fig. 18) their mesogloea was exceedingly thin, with smooth 

 surfaces and they were nnich broader than in the lower region 

 (Fig. 19) the mesogloea in this portion of their extent being much 

 thicker and its surfaces raised into numerous processes and lobes 

 for the Support of the parieto-basilar and basilar muscles, the former 

 of which did not, however, form a fold upon the surface. The 

 muscle pennons of the primaries and secondaries were strong and 

 ended abruptly only at their inner edges. The reproductive organs 

 were entirely conflned to the upper broader parts of the mesenteries 

 and were borne by those of the primary and secondary cycles, with 

 the possible exception of the directives; the tertiaries were sterile. 



In form and coloration this specimen so closely resembled the 

 individual of Adinia nivea shown to the left in Lesson's figure of 

 that species (1830, tab. 3, flg. 8 B) that there seems no doubt of its 

 identitj". Lesson, however, describes the species as capable of 

 assuming various forms; his description runs thus: ,,Sa partie supe- 

 rieure peut aussi rentrer avec les tentacules et se cacher dans l'am- 

 pleur moyenne de corps. Enfin, l'enveloppe est tres-lisse, tres-douce 

 au toucher et seulement marquee de quelques rades ou plissures 

 verticales." The goblet-like form of the column cannot, therefore, 

 be regarded as absolutely characteristic of the species, but when 

 associated with a coloration resembling so closely that shown in 

 Lesson's figures it certainly becomes of importance. 



The majority of the Synonyms of Lesson's species are based 

 solely on his description and only in three cases was the name of 

 his species applied to specimens actually examined, namely in the 



