THE EVIDENCE OF THE THYROID GLAND 



207 



epithelium of the uterus masculiuus and its processes is extraordi- 

 narily elongated, the chitin covering being thick. In these animals, 

 then, the common chamber or uterus into which the genital ducts 

 empty, which, like the corresponding chamber in the scorpion, 

 occupies the middle region of the operculum, is a large and con- 

 spicuous organ. Further, and this is a most striking fact, the 

 uterus masculinus does not open direct to the exterior, but into the 

 genital cavity, " which lies above the uterus, so that the latter is 

 situated between the lower wall of the genital cavity and the outer 

 integument." The opening, 

 therefore, of the uterus is not 

 external but internal, into the ^ A 



large internal space known 

 as the genital cavity. The 

 arrangement is shown in Fig. 

 91, taken from Tarnani's 

 paper, which represents a 

 diagrammatic sagittal section 

 through the exit of the male 

 genital duct. Yet another 

 most striking fact is described 

 by Tarnani. This genital 

 cavity is continuous with the 



Gen . Ch. 



I 



Ut.Masc. 



— I -II 



Ut.Masc. 



1 - II 



WJ— -Int. Op 

 --Eart.Op. 



.---Ill 



Fig. 91. — Sagittal Median Diagrammatic 

 Section through the Operculum of the 

 Male Thelyphonus. (From Tarnani.) 



pulmonary or gill cavities on The thick line is the operoulum> composed of 



each side, SO that instead of a two segments, I. and II. Ut. Masc, uterus 

 single opening for the genital masculinus ; Gen. Ch., genital chamber ; Int. 

 L ° Op., internal opening ; Ext. Op., external 



products and one on each Side opening common to the genital and respira- 

 for each gill-pouch, as would tory organs, 

 be the case if the arrangement 



was of the same kind as in the scorpion, there is a single large 

 chamber, the genital chamber, common to both respiratory and 

 genital organs. 



This genital chamber, according to Tarnani, opens to the exterior 

 by a single median opening between the operculum and the succeed- 

 ing segment ; similarly, a communication from side to side exists 

 between the second pair of gill-pouches. I have been able to 

 examine Hypoetonm formosus and Thelyphonits caudatus, and in both 

 cases, in both male and female, the opening to the exterior of the 

 common chamber for respiration and for the genital products was 



