[258] The foremost extremity of the segmental duct presents, according to Gasser, curious irregularities and an anterior completely isolated portion is often present.
[259] Correct figures of the early stages of these structures were first given by Kölliker, but the correct interpretation of them and the first satisfactory account of the development of the excretory organs of Birds was given by Sedgwick (No. [549]).
[260] These external glomeruli were originally mistaken by me (No. [539]) for the glomerulus of the pronephros, from their resemblance to the glomerulus of the Amphibian pronephros. Their true meaning was made out by Sedgwick (No. [550]).
[261] This is also called parovarium (His), and Rosenmüller’s organ.
[262] Weber (No. [553]) states that a uterus masculinus is present in the Rabbit, but his account is by no means satisfactory, and its presence is distinctly denied by Kölliker.
[263] According to Sedgwick some of the anterior segmental tubes of Aves form an exception to the general rule that there is no outgrowth from the segmental or metanephric duct to meet the segmental tubes.
[264] As mentioned in the note on p. [729] Sedgwick maintains that the anterior segmental tubes of the Chick form an exception to this general statement.
[265] It is by no means certain that the transportation outwards of the genital products by the abdominal pores in the Cyclostomata may not be the result of degeneration.
[266] This suggestion has I believe been made by Fürbringer.
[267] The papers of Fürbringer, Semper and Waldeyer contain full references to the literature of the Vertebrate excretory organs.