223 



connection I should like to call attention to the distal articular sur- 

 face of the calcaneus, which I have always considered one of the most 

 difficult to describe in the human body. It may be said to be in the 

 main triangular, the base being above. The dorsal tibial angle forms 

 the distal end of the sustentaculum. Usually it projects slightly, 

 overhanging the distal articular surface. Occasionally it projects very 

 considerably toward the navicular and then, according to Pfitzner, 

 it is the calcaneus secundarius. But in my opinion it cannot always 

 be considered a dorsal element. It is not excessively uncommon to 

 find, more or less marked, the condition represented in Fig. 4, in which 

 it insinuates itself between the cuboid and the navicular and, worse 

 still, between the processes on these bones representing the cuboides 

 secundarium. The calcaneus secundarius surely should not be close 

 beside the cuboides secundarium if the one be dorsal and the other 

 plantar. 



A comparison of the cuboides secundarium, as shown in Fig. 1, 

 with the calcaneus secundarius, as shown in Fig. 4, is very suggestive; 

 but it suggests difficulties rather than explanations. The key to the 

 puzzle is wanting. 



Harvard Medical School, May 19th, 1910. 



Literature. 



1) DwiGHT, T., A clinical atlas of variations of the bones of the hands 

 and feet, Philadelphia and London 1907. 



2) — , A criticism of Pfitznee's theory of the carpus and tarsus. Anat. 

 Anz., Bd. 35, 1909, p. 366—370. 



3) Gruber, W., Ueber einen neuen sekundären Tarsalknochen — Cal- 

 caneus secundarius — mit Bemerkungen über den Tarsus überhaupt. 

 Mem. de l'Acad. des Sc. de St. Petersbourg, T. 17, 1871, No. 6. 



4) Krause, W., Skelett der oberen und unteren Extremität, v. Barde- 

 lebens Handbuch der Anatomie des Menschen, Bd. 1, Abt. 3, 1909. 



5) MoRESTiN, H., Note sur un scaphoide s'articulant par de larges 

 facettes avec le cuboide et le calcaneum. Bull, de la Soc. anat. de 

 Paris, T. 69, 1894, p. 798—800. 



6) Pfitzner, W., Beiträge zur Kenntnis des menschlichen Extremitäten- 

 skeletts. VII. Die Variationen im Aufbau des Fußskeletts. Morphol. 

 Arb., Bd. 6, 1896, p. 245—527. 



7) SuTTON, B., On an occasional articulation between the cuboid and 

 the head of the astragalus. (Discussion : Macalister and Thane.) 

 Proc. Anat. Soc. Gr. Brit, and Irel, 23. May, 1892. Journ. Anat. 

 and Physiol, p. XVIIL 



