Concerning the skull, he was in the ’80’s back to it with a will.  His line of attack was through the lampreys and hags and the higher cartilaginous fishes, and he was following up a revolutionary conception (already hinted at in his Hunterian Lectures in 1864, and later in a Royal Society paper on Amphioxus in 1875), that the trabeculae cranii, judged by their relationships to the nerves, may represent a pair of prae-oral visceral arches.  In his unpublished notes there is evidence that he was bringing to the support of this conclusion the discovery of a supposed 4th branch to the trigeminal nerve—­the relationships of this (which he proposed to term the “hyporhinal” or palato-nasal division) and the ophthalmic (to have been termed the “orbitonasal” (A term already applied by him in 1875 to the corresponding nerve in the Batrachia. ("Encyclopaedia Britannica” 9th edition, volume 1 article “Amphibia."))) to the trabecular arch and a supposed prae-mandibular visceral cleft, being regarded as repetitional of those of the maxillary and mandibular divisions to the mandibular cleft.  So far as I am aware, von Kupffer is the only observer who has given this startling conclusion support, in his famous “Studien” (Hf.  I. Kopf Acipenser, Munchen, 1893), and from the nature of other recent work on the genesis of parts of the cranium hitherto thought to be wholly trabecular in origin, it might well be further upheld.  As for the discovery of the nerve, I have been lately much interested to find that Mr. E. Phelps Allis, junior, an investigator who has done grand work in Cranial Morphology, has recently and independently arrived at a similar result.  It was while working in my laboratory in July last that he mentioned the fact to me.  Remembering that your father had published the aforementioned hints on the subject, and recalling conversations I had with him, it occurred to me to look into his unpublished manuscripts (then being sorted), if perchance he had gone further.  And, behold! there is a lengthy attempt to write the matter up in full, in which, among other things, he was seeking to show that, on this basis, the mode of termination of the notochord in the Craniata, and in the Branchiostomidae (in which the trabecular arch is undifferentiated), is readily explained.  Mr. Allis’s studies are now progressing, and I have arranged with him that if, in the end, his results come sufficiently close to your father’s, he shall give his work due recognition and publicity. (See “The Lateral Sensory Canals, the Eye-Muscles, and the Peripheral Distribution of certain of the Cranial Nerves of Mustelus laevis” by Edward Phelps Allis, junior, reprinted from “Quarterly Journal Micr.  S.” volume 45 part 2 New Series.)