630 ' REPORT — 1889. 



of the muscles of the chimpanzee, but our knowledg'e of the myology of the gorilla 

 is less complete. So far as can be judged from the limited number of observations 

 it seems probable that muscular variations are about as common in these animals as 

 in man. The diftereuces between the arrangement of the muscles in the gorilla and 

 chimpanzee are undoubtedly less than those between either of these animals and 

 man. It is not easy to determine which of them approaches nearest to man. The 

 following are a few of the more interesting points observed. 



In both gorilla and chimpanzee the attachments of the latissimus dorsi and 

 serratus magnus to the trunk were more extensive than in man. This may be 

 associated with their more frequent use in climbing. The dorso-epitrochlearis 

 (Wood) was better developed in the chimpanzee than in the gorilla. In both it was 

 muscular, while in man it is represented by a band of fascia. In both gorilla and 

 chimpanzee the deep head of the pronator radii teres was present, but it is often 

 absent. The radial head of the flexor sublimis was present in gorilla and 

 chimpanzee, and the flexor carpi radialis had also an origin from the radius. The 

 pal maris longus was absent in the gorilla, but present in the chimpanzee. This muscle 

 has only been observed once in the gorilla. The extensor indicis went to index finger 

 onl}', Ln the gorilla and chimpanzee. According to Bischoif, the gorilla is the only ape 

 that resembles man in having a special extensor for the index finger. The extensor 

 primi internodii pollicis is said to be peculiar to man. It was absent in the chimpanzee, 

 but present in a rudimentary form in the gorilla, as in the latter a small tendon was 

 prolonged from the extensor ossis metacarpi pollicis to the first phalanx of the 

 thumb. The flexor longus pollicis was represented in the goriUa merely by a small 

 tendon in front of the thumb, which, however, had no comiectiou with the deep 

 muscles on the front of the forearm. In the chimpanzee the index portion of the 

 flexor profundus digitorum gave a small tendon to the thumb. The gluteus 

 maximus is much smaller in the gorilla and chimpanzee than in man, and its arrange- 

 ment ia such as to give rise to a marked difl'ereuce in the contour of the gluteal 

 region. In the gorilla and chimpanzee the two heads of the biceps flexor cruris were 

 quite distinct, and not joined, as in man. The soleus, however, had a tibial origin. 

 It is generally described in the chimpanzee and gorilla as arising from the fibula only. 

 According to Bischofl', the interossei muscles of the foot are arranged in all the 

 anthropoid apes in the same way as the interossei of the hand, viz., the dorsal 

 interossei abduct from a line passing'through the third digit. In the human subject 

 the line is through the middle finger in the hand and the second toe in the foot. I 

 find this to be also the case in the gorilla. In neither gorilla nor chiaipanzee was 

 the peroneus tertius present and, so far as I am aware, this muscle has not been 

 observed in the anthropoid apes. It is generally, although not constantly, present 

 in man. 



6. 071 the Structure and Function of the Dorsal Papillce in Nudihranchiata. 

 By Professor W. A. Heedman, D.Sc, F.L.8. 



The projections from the dorsal surface of the body in Nudibranchs include: — 



1. The Rhinophores or dorsal tentacles. 



2. The true Branchije. 



3. The Cerata or dorsal papillae. 



The rhinophores are placed near the anterior end of the body, are supplied by 

 large nerves springing fi-om the cerebral ganglia, and are undoubtedly sense organs. 

 They are present in all the forms I have examined. 



The branchiae, although posfsibly not ctenidia, are specialised organs of respira- 

 tion. They are not always present. 



The cerata, which are the special subject of this investigation, are often termed 

 dorsal papillae and branchial papillae, and have been supposed by some zoologists 

 to function as branchiae. They are not present in all Nudibranchs, but in many 

 cases they are very large and conspicuous. I find the cerata in the genera which 

 I have examined to be of two kinds: — 



1. There are those which contain large diverticula of the liver, as in the case 

 of the genera Eolis and Doto. 



