260 ZAGLOSSUS. 



author, who illustrates such a transitional series by hairs and spines selected 

 from different parts of the same animal. 



Measurements. — The largest recorded Proechidna is that made bj^ 

 Rothschild (1892) the type of his nigroaculeata. This specimen measured in 

 the flesh 31 inches (about 640 mm.) in total length. Dubois (1881) records 

 an adult that measured 620 mm. from the tip of the snout to the tip of the tail. 

 Two adult skins, M. C. Z., Nos. 12,414 and 12,415, measure 717 and 539 respec- 

 tively, but there is no way of proving whether the specimens are overstuffed. 

 Rothschild's measurement is probably nearly maximum for adults. Weber 

 (1888) gives measurements taken from five skins but all are less than 640 mm. 



The naked part of the rostrum in M. C. Z. 12,414, measures 101 mm. The 

 claws of the left fore and hind feet measure : — 



The spur in this specimen is 7 mm. long. 



A series of cranial measurements is given in the part of this paper deahng 

 with the osteology. 



MUSCULATURE. 



Muscles of the skin. — As in the case of the Echidna, the panniculus 

 carnosus is very remarkably developed, so as to form a loose muscular sac in 

 which are imbedded the bases of the spines. By its contraction this muscle 

 erects the spines, which thus form a bristling armament. Fewkes (1877) has 

 described and named as separate muscles, several of the subdivisions of this 

 enveloping sac in the Echidna, and the same divisions appear to be present in 

 the Proechidna. Anteriorly the panniculus extends as far as the parietal region, 

 whence its fibers extend diagonally forward just back of the eyes and pass 

 transversely under the chin. Medially on the forehead there is a narrow space 

 devoid of muscle fibers where the imion of the two lateral portions of the muscle 

 is by fascia only. There is an attachment also along the posterior part of the 

 squamosal bone on each side. From the head, the fibers are continued on both 

 dorsal and ventral sides of the body to the tail and laterally on to the legs. 

 Dorsally the muscle is thickest midway between the median line and the ventral 

 border of the body and forms a continuous sheet across the back where the 



