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Show 886 MR. WALTER E. COLLINGE ON THE SENSORY [Dec. 17, elastische Fasern beigemischt sind. Mitten durch die Kapsel geht noch ein weisser, aus Bindegewebe gefertigter, 1| Linien dicker, fester Strang, der von einem knorpeligen Fortsatz des Kopfknorpels kommt und zur Befestigung und Erhaltung der Form der Kapsel wesentlich beitragt. Die bezeichnete Kapsel ist angefiillt mit einer hellen Gallertmasse, und in diese eingebettet liegen die Ampullen der Schleimkanale. In der Gallertmasse sieht man ausser Kernen noch Bindegewebsmaschen und elastische, oft in weiten Bogen isolirt verlaufende Fasern, welche aile sowohl mit der W a n d der Ampullenkapsel als auch mit den Ampullen selber in Verbindung stehen, und die Befestigung derselben innerhalb der Gallerte sichern." 2. Structure and Varieties. I have quoted Leydig at some length, for his account is the first and only one that makes any pretence at detail. Judging from Leydig's description and figure, he only met with one form of canal, whereas there are three distinct types. In the occipital group the number of pores varies from seven to eleven, each leads into a long tube or canal which widens out into a sac-like base (PL LIII. fig. 9, a), the ampulla being ill-defined. In some cases where the pores of the canals are in a row and tbe canals or tubes run parallel to each other, some are longer than others, the length from the pore to the base of the canal varying as follows:- Specimen No. 1. No. 2. No. 3. No. 4. millim. millim. millim. millim. Pore 1 37 35 34 30 „ 2 25 22 20 18 „ 3 34 30 20 29 4 25 21 28 18 ,5 i, ?> ,i 5 20 18 18 29 6 30 29 28 20 7 33 35 29 26 The measurements were made on four different specimens and of the first seven pores (PL LIII. fig. 9, a). In the supra- and sub-orbital groups the pores are more closely grouped. Each leads into a narrow tube which passes downwards and with its fellows O P E N S INTO A SINGLE W I D E T U B E ; this continues for a short distance and then terminates in a spongy mass of ampullae (PL LIII. fig. 9, 6). The whole of the spongy mass is enclosed in an ill-defined connective-tissue capsule. In the maxillo-mandibular groups the canals approach more nearly to those described and figured by Leydig, and it seems very probable that he examined only those in this region and in the region of the Y-Shaped commissure. Thus in Chimcera it will be seen that there are three types of ampullary canals, viz.:-(1) A simple unbranched tube which |