The Blue Gyancea. 153 



corresponding to the deeper incisions of the margin, eight 

 narrower and lower, corresponding to the incised points of the 

 flaps. The folds of gelatinous membrane which constitute 

 these arches are very complex, and both sets are the seats of 

 elaborate ramifications of the canals that proceed from the 

 digestive cavity, and carry water, charged with nutrient parti- 

 cles and with oxygen for respiration, to the exterior of the 

 system. Up each side of the greater arches the ramification 

 takes the form of a succession of loops seated on the marginal 

 canal ; whereas, to the summit of each smaller arch proceeds a 

 straight canal, which sends off from each side a series of curved 

 coecal processes, like the beards of an elegant feather. The 

 point of the canal which would represent the quill of this 

 feather merges into the singular little organ which we must 

 consider as performing the function of an eye. 



These organs are extremely interesting in their structure, 

 and are worthy of more attention than is usually bestowed upon 

 them. They occur in certain genera of Medusas, which in other 

 respects have a higher organization, and are always protected 

 with these hoods of membrane, whence such genera have been 

 grouped together under the title of Steganophthalmata, or 

 Covered-eyed ; while other zoologists have associated them with 

 the family Lucernariadce, as an order named Liicernaridce* 



In each genus the organ consists of a round or ovate body, 



of an opaque red or yellow colour, pendulous from the summit of 



the protecting hood, or arched fold of membrane at the edge of 



the disk. It is connected with the disk by a slender footstalk, 



into which one of the canals passes as already described ; the 



interior of this pedicel being delicately ciliated. 



* Professor Greene's Manual of the Coelenierata. Surely a most objection- 

 able designation ; for the termination idee, changed to adce, when the noun is of tho 

 first declension, or ends in ospurum (equivalent to iu.i, eus, etc., in Latinized forms) — 

 tho Greek patronymic — has been accepted by zoologists as the distinction of family 

 rank ; and to form an ordinal appellation, including the family, on the same model, 

 is most irregular, and only productive of confusion. Indeed, the form Lucernaridee 

 is incorrect, since Lucernaria being of the first declension, the only patronymic 

 that can be formed of it is Lucernariadce. I will use this opportunity of adding a 

 word on the usage of naturalists in constructing family designations. If the rule 

 I have just mentioned is the true one, such forms as Pelagidce, Oculinidce, Colidce, 

 Jlhizostomidcc, are incorrect, and should be rejected ; the first two should be Pela- 

 giades and Ooulinadee, the terminal a of the component noun being changed into 

 adm ; tho third Coliaclce, because Colius (= os purum) of the second declension 

 makes its patronymic in ada i; whereas tho fourth should be BhizoslomatidoB, 

 since ttoma is not of the first but of the third declension, and forms its patronymic 

 from tho genitive. Some naturalists, who are competent scholars, form the ter- 

 mination always in idcB, believing the rule to have reference to elSos, resemblance. 

 I have, however, tho best authority for stating that at the tirst proposal and ado >-• 

 tion of tho termination idm for zoological families, at a meeting of tho Zoological 

 Club, composed of tho lato Mr. Vigors, Professor Bell, and two or three other 

 eminent naturalists, whoso names I cannot now with certainty mention, tho con« 

 struction of the Greek patronymic was the rule accepted, and that a compound of 

 eJSos was not even thought of. 



