[Footnote: The part C is that alone described by Santorini, who named it "elevator urethrae," as passing beneath the urethra. The part B is that first observed and described by Mr. Guthrie as passing above the urethra. The part F represents the well-known "transversalis perinaei," between which and the part C there occasionally appears the part E, supposed to be the "transversalis alter" of Albinus, and also the part D, which is the "ischio bulbosus" of Cruveilhier. It is possible that I may not have given one or other of these parts its proper name, but this will not affect their anatomy.] [Illustration: Abdomen, showing blood vessels and other internal organs.] Plate 55--Figure 2 Fig. 3, Plate 55.--The membranous urethra A is also in some instances embraced by two symmetrical fasciculi of muscular fibres B B, which arising from the posterior and lower part of the symphysis pubis, descend on either side of the canal and join beneath it. The muscles B C, Fig. 2, Plate 55, are between the two layers of the deep perinaeal fascia, while the muscle B B, Fig. 3, Plate 55, lies like the forepart of the levator ani, C C, behind this structure and between it and the anterior ligaments of the bladder. [Footnote] As to the interpretation of the muscle, I, myself, am inclined to believe that it is simply a part of the levator ani, and for these reasons--1st, it arises from the pubic symphysis, and is inserted into the perinaeal median line with the levator ani; 2nd, the fibres of both muscles overlie the forepart of the prostate, and present the same arrangement in parallel order; 3rd, the one is not naturally separable from the other. [Footnote: This is the muscle, B B, which is described by Santorini as the "levator prostatae;" by Winslow as "le prostatique superieur;" by Wilson as the "pubo-urethrales;" by Muller as not existing; by Mr. Guthrie as forming (when existing), with the parts B C, Fig. 2, Plate 55, his "compressor isthmi urethrae;" and by M. Cruveilhier as being part of the levator ani muscle. "As in one case," (observes Mr. Quain,) "I myself saw a few vertical muscular fibres connected with the transverse compressor, it has been thought best to retain the muscle in the text."--Dr. Quain's Anat., Am. Ed. vol. ii. p. 539.] [Illustration: Abdomen, showing blood vessels and other internal organs.] Plate 55--Figure 3