i5S4.] Correspondence. IQ7 



the temporal imiscles (Owen. Anut., II, 93). Finding upon dissection 

 ofajoung Cormorant tiie raphe but slightl}' ossified, I would make the 

 following suggestion of its evolution. In some birds, especially those 

 with small crania, the temporal muscles meet in the median line over the 

 occiput. In the Cormorant we find this carried to an extreme, the mus- 

 cles extending back for about an inch over the nape of the neck. This 

 increase in the size, and consequently in the power of the temporal mus- 

 cles, is evidently of great advantage to a bird of ^the Cormorant's habits. 

 But were the muscles not held in place, they would slide over the occiput 

 with the first contraction. This could have been avoided by the muscles 

 being attached to the vertebrae, or to a theoretical ligamentum nuchse. 

 But such an origin would have bound the head in extension, a condition 

 incompatable with the life of the bird. We therefore find the only other 

 possible contrivance, a solid guy, extending from the cranium. This guy 

 has been made by the conversion of the fibrous raphe into bone. In 

 young Cormorants the raphe, though dense, is not ossified. Were the guy 

 represented "by a spinous outgrowth from the skull, motion of the head 

 upon the neck would be seriously impaired, as the spine is fastened down 

 to the neck by fascia and the skin. Therefore we find a ball and socket 

 joint developed between the spine and the cranium. 



This beautiful adaptation of limited material to a given end points 

 strongly to a Lamarkian mode of development ; its development \>y gradual 

 selection is hard to understand. When we consider that demand upon 

 a muscle leads to its increased size ; that bone is fi-equently formed in 

 tendons — and such the raphe is — to meet mechanical needs; that bursae 

 form in connective tissue at points of friction, we see how all may be the 

 direct result of demand upon the temporal muscles. Once given the 

 structure, natural selection comes into play in the increase of Cormo- 

 rants ; but first cause and the means by which the results of a first cause 

 are maintained should never be confounded. 



Finally, this bone, as the result of ossification of a common tendon of 

 a pair of muscles, is an anatomical rarity. — J. Amory Jeffries, Boston, 

 Mass. 



CORRESPONDENCE. 



^Correspondents are requested to ivrite brieHy and to the point. No attention -will 

 be paid to anonymous communicatio7is,'\ 



Trinomials Are Necessary. 



To THE Editors of The Auk : — 



Sirs: Referring to Mr. Chamberlain's timely query, 'Are Trinomials 

 Necessary.?' in the January number of this periodical, I beg to say a 

 woi-d by way of supplementing Mr. Allen's excellent remarks upon this 

 interesting question. He has covered the ground so well that, in heartilv 

 endorsing the tenor and substance of all he has said, I only wish to add 



