542 ANATOMY OF VERTEBRATES. 



cloaca behind the genital orifices; the forepart of the cloaca 

 is slightly dilated, and the rectum opens therein by a valvular 

 protrusion. 



The formation and disposition of the reniportal and renal or 

 emulgent veins have been previously described. 



§ 97. Adrenals of Hamatocrya. — The bodies called ' suprarenal 

 capsules,' 'renes succenturiatag," capsulaj atrabiliarise,' &c., in Man, 

 may be represented in the lowest Vertebrates, e.g. the Myxinoids, 

 in the form of a pair of small oval lobulated bodies situated in 

 advance of the kidneys, and close or adherent to the portal sinus. 

 In the lamprey a glandular body lies between the aorta and car- 

 dinal vein, adhering to the coats of the latter ; but it has not the 

 characteristic structure of the adrenals in higher Vertebrates. In 

 ordinary Osseous Fishes the adrenals have been recognised as 

 roundish bodies of a light grey colour ; commonly two, rarely 

 three or more in number, situated sometimes near the middle, 

 oftener at the hinder ends of the kidneys, at or near the entry of 

 the hajmal canal ; but in the Eel they are found where the two 

 kidneys unite. They are commonly symmetrical in position ; 

 but in the genus Scomber one adrenal is in advance of the other ; 

 and in Phuronectidce they lie both on the same side of the body. 

 Sometimes they lie free, sometimes they are imbedded in the renal 

 tissue : they usually possess a proper capsule, and present a 

 minutely granular texture without distinction of cortical and 

 medullary parts. Their surface is smooth in some Fishes, irregular 

 in others ; in large and old Pike three adrenals have been seen ; 

 but in the young (' Jack,' one foot long), the kidney has been 

 found to be beset with a number of small adrenals.' The yellow- 

 ish adrenals of the Sturgeon occur as numerous small glandular 

 bodies studding the dorsal surface of the kidney. Four or five 

 similar bodies are sometimes found in the Skate ; but more com- 

 monly in Plagiostomes, the adrenals are represented by a single 

 elongated narrow yellowish and lobulate body, situated behind the 

 kidney, and sometimes extending behind the dilated ureter.^ The 

 adrenal in Fishes, whether compacted or subdivided, consists of an 

 aggregate of lobules, with proper capsules, connected by looser 

 connective tissue : each lobule consists of cells of about ^juVo tli of 

 an inch in diameter, containing nuclei, fiit-globules, and molecular 

 particles, tlie latter being mostly aggregated about the nucleus. 

 Processes from the lobular capsule pass" inward and insulate the 

 multinucleate cells. In the young Pike the moleciilar-clothod 

 nuclei acquire a cell-wall, become liberated, and converted into 



' COLXXiVU. •-• OXXI. 



