1881.] ANATOMY OF THE ERINACETD.«. 405 



the shortness of the xiphisternum ; and the mesosternum is made 

 up of three or two segments only. 



The pelvic opening contrasts remarkably with that of Gymnura; 

 its transverse diameter, measured between the acetabula, is nearly 

 or quite half its longitudinal, whereas in G. rajjlesii it is scarcely 

 one ninth ; the symphysis pubis is also much deeper, especially in 

 U. europceus; the tuber ischii is short and rounded off; and the 

 posterior margin of the ramus of the pubis and ischium is convex, 

 not concave. 



Except in E. europcBus and its varieties, there is a supracondylar 

 foramen in the humerus. The carpus is formed on the same plan as 

 in Gijmnura ; but the scaphoid and lunar bones are early united, 

 leaving no trace of their original separate condition. lu the femur 

 the convexity which in Gymnura represents a third trochanter is 

 less prominent and more extended, indicating a long muscular, as 

 opposed to a tendinous, insertion of the muscles attached to it, and 

 pointing to the less active habits of the animals. Other limb bones, 

 both in the anterior and posterior legs, are generally similar to those 

 of Gymnura, a single departure from the typical number of five 

 digits in the fore and hind feet beir.g seen in E. heterodactyliis and 

 its varieties, where the hallux is altogether wanting. 



In the muscular anatomy the chief differences between the species 

 of this genus and Gymnura are found in the much greater develop- 

 ment of the panniculus carnosus, and in other minor points to be 

 noticed further on. 



To the cutaneous muscles described in Gymnura rafflesii there are 

 in all the species of Erinaceus others superadded, which are related 

 to the well-known defensive attitude assumed by these animals when 

 frightened. They have been figured in the anatomical plates of 

 Cuvier and Laurillard', and described by Prof. Huxley". 



In the general myology the following differences are especially 

 noticeable : — • 



In the face the sygomaticus major is inserted into the orbicularis 

 oris and integument of the upper lip at a short distance in front of 

 the angle of the mouth. The temporal muscle arises also from the 

 zygomatic arch, as in Gymnura ; but its fibres do not take origin so 

 far back as the mastoid process. The digastric is single, and does 

 not unite with its fellow of the opposite side between the jaws ; it 

 has nearly the same calibre throughout, but is crossed about the 

 middle by an oblique tendinous inscription, corresponding precisely 

 in position to the tendinous intersection in Gymnura. The viylo- 

 hyoid is well developed, consisting of an anterior and posterior por- 

 tion. Cleido-occipital is slender and quite uncomiected with the 

 trapezius. The serratus maynus is not united with the levator unyuli 

 scapulce. 



The pyramidales are well developed, in striking contrast with 

 Gymnura, in which they are rudimentary or absent. The recti ab- 

 dominis et sternalis are connected with the pubic bones by three 

 instead of four tendons, the missing tendon corresponding to the 

 ' Planches de Myologie. ' Aiiat. Vevf, Aiiiniuls, p. 445. 



