FREDERICK TILM.V AM) LTTIIKR F. WARRKX 



5. Torpc<l <>n Ha /n. d'Krchia ('96). 109 No evidence of de- 

 velopmental differentiation into ;i pineal organ was found in 

 the early stages of this form. A well-developed paraphysis, 

 however, is present . 



HOLOCEPHALI 



1. Call&rhynchus. Parker and Haswell ('97). 3 - 



2. Cliiititirrti inonxlroMi. Studnicka ('96). 386 In both of these 

 forms there is a well-defined epiphysis and a large dorsal 

 sac. The pineal organ has a form similar to other :elachians; 

 that is to say, a fairly well-marked proximal portion, a long, 

 >lender stalk extending forward and expanding slightly to form 

 an end-vesicle at its extremity. 



In all, seventeen species of selachians have been examined; 

 that is, ten Elasmobranchs, five Rat/*, and two Holocephali. 

 In two species a complete absence of the pineal organ is reported, 

 namely, Torpedo ocellala and Torpedo marmorata. All of the 

 other species present a pineal organ more or less well developed. 

 In one form, that is, Gale us cam's, histological evidence has been 

 presented showing that there is some reason to believe that a 

 secretory function obtains in the pineal organ of this form. 

 "Wherever mention is made of the paraphysis it seems to be an 

 organ of considerable size. 



3. Comparative anntonnj and hixtolo<m of tin- epiphysecd complex 



in i /< i no ids 



In all the species of ( lanoids there develops a fairly well- 

 marked pineal organ. In one form only, namely, Amid, is there 

 any indication of the presence of a parapineal organ. Stannius, 373 

 giving the first description of the structure of the parapineal 

 organ in Adpenser sturio in 1S.~>-1. slates that the structure is a 

 wide evaginat ion extending from the roof of the interbrain and 

 connected with the comniissura habenularis. It reach-,- for- 

 ward to a fossa, in the roof of the skull. Cat tie 1 ' 1 " in ISS'J. also in 

 Aci/x nwr xhirio. and Goronowitsch 188 in 1SSS, on .lr//"'//xr/- 

 riilln'niix, gave similar descriptions of the pineal organ. ( lar- 

 man 113 in IX'.HI and Johnston" 1 in 1 ( .H)I by means of the ( iolgi 



