594 MOEPHOLOGICAL METHOD AND EECENT PROGRESS IN ZOOLOGY. 



the lampreys and hags (1) in the total a])sence of paired tins; (2) in the 

 presence of branehia% ordinarih' 7 in num])er, l-i in Bdellodoma 

 polytrema^ nuniericall}' variable in individuals of certain species 

 between 6 and 14, and doul)tfully asserted in the young of one to be 

 originall}" 35; and (3) in the carr^-ing up of their oral hypopophysis 

 by the nasal organ, whereb}" it perforates the cranium from above, as 

 contrasted with all the higher Vertebrata, in which, carried in with 

 the mouth sac, it perforates it fi-om ])cneath, exhibit morphological 

 characters of an extraordinary kind. And if we are to express these 

 characters in terms we may distinguish the Cyclostomes as cqyteryglal 

 and cpH-i'an'iate^ the higher Vertebrata as Jiypocraniate." But this, 

 notwithstanding the aforementioned subdivision of the Pisces into 

 two series, which would associate the teleosts and ganoids with the 

 cyclostomes, as distinct from the rest, receives support from recent 

 study of the head-kidney b}^ a Japanese, who seeks to show that the 

 organ so called in the Elasmobranchs is of a late-formed tj^pe peculiar 

 to itself, and it is also in agreement with one set of conclusions 

 previously deduced from the study of the reproductive organs. 



To deal further with the fishes is impossible in this address, except 

 to remark that recent discovery in the Gambia, that the young of the 

 Teleostean genera lleterotis and GymriarcJms bear tilamentous exter- 

 nal gills, renders significant beyond expectation the alleged presence 

 of these among the loaches, and shows that adaptive organs of this 

 t3'pe are valueless as ci'iteria of affinity. 



In paleontology, as in recent anatomy, our records of detail have 

 increased beyond precedent, often but to shoAV how deficient in knowl- 

 edge we are, how contradictory are our theories and facts. 



In dismissing the fishes, I wish to comment upon our accepted terms 

 of orientation. To speak of the median fins as dorsal, caudal, and 

 anal, of the pelvic as ventral, and of the pectoral in its varj-ing degrees 

 of forward translocation as abdominal or thoracic, though a conven- 

 tion of the past, is to-day inaccurate and absurd. I question if the 

 time has not come at which the terms thoracic (pulmocardiac) and 

 abdominal are intolerable, as expressing either the subdivisions of the 

 body cavit}" or an^'thing else outside the Mammalia, which alone 

 possess a diaphragm. Kven in the birds, to grant th(> utmost, the 

 subdivision of the cd'lom. if accurately described, nuist be into pul- 

 monary, hyper-pulmonary, and cardio-abdominal chambers, while 

 with the reptiles the modes of subdivision are so complex that a special 

 terminolog}' is necessary for each of the several types extant. 



^' It i^! an interesting circumstance, if their "ciliated sac" is rightly homologized, 

 that ^l/;;;>/y/o.n(,s- and the Tunicata i)resent a corresponding dissimilarity, allowance 

 being made for the fact that in Butrylhis, Cioodf^irid, and J'ohicdvjHi the sac overlies 

 the ganglion. It is pertinent here to recall the ammoccete-Hke condition of the 

 "endostyle" in Oikopleurajlahellum. 



