33° 
NATURE 
Ata 9 ap 
also on Heat ; and Mr. Shaw (Emmanuel), on Conservation of 
Energy. 
The followin gare advanced lectures :—Organic Chemistry, 
Prof. Dewar; Physical Optics, Mr. Trotter (Trinity); Elec- 
tricity and Magnetism, Mr, Garnett (St. John’s). 
Practical Chemistry at the University, St. John’s, Caius, and 
Sidney Laboratories. Practical Physics at the Cavendish Labo- 
ratory; also advanced demonstrations by Messrs. Shaw and 
Glazebrook. 
In geology Prof. Hughes is lecturing on Stratigraphical 
Geology ; Mr. Tawney, on Fossil Echinoderms and Crustaceans, 
and on-Petrology. Dr. Roberts (Clare College) is also taking a 
class in Petrology; and Prof. Hughes makes periodical field 
excursions, 
Dr. Vines (Christ’s) lectures on the Anatomy of Plants, with 
practical work ; Mr. Hicks (Sidney), on Elementary Botany, 
chiefly Morphology ; Mr, Saunders (Downing), on Elementary 
Botany ; and Mr. Hillhouse, on the Anatomy and Physiology 
of Plants, at the Museums. 
Prof. Newton takes Vertebrata this term (lectures on Geo- 
graphical Distribution once a week). Mr. Balfour gives ele- 
mentary and advanced lectures on Morphology, with practical 
work, as usual. Dr. Foster’s elementary course of Physiology 
is continued ; and the advanced lectures are Dr. Gaskell’s, on 
Respiration ; Mr. Langley’s, on the Digestive System ; and Mr. 
Hill’s, on the Central Nervous System. 
Prof, Humphry lectures on the nervous system and the Organs 
of Special Sense, and takes a class for Tripos and 2nd M.b. 
work in Anatomy and Physiology. Dr. Creighton has a class 
for Osteology, and Practical Human Anatomy commenced on 
January 20, 
Prof. Stuart is lecturing on the Theory of Strictures. The 
Demonstrator of Mechanism will form classes in elementary and 
advanced mathematics applicable to engineering. 
The last Senior Wrangler under the old regulations is Mr. R. 
A. Herman, of Trinity College, educated at King Edward’s 
School, Bath; his private tutor was ‘Mr. Routh. The second 
- wrangler is Mr. J. S. Yeo, of St. John’s College, educated at 
Blundell’s School, Tiverton ; his private tutor was Mr. R. R. 
Webb, of St. John’s. The third wrangler is Mr. S. S. Loney, 
of Sidney College, educated at Maidstone Grammar School and 
Tonbridge School: private tutor, Mr. Routh. St. John’s has 
four wranglers of the first eight ; Trinity has only one wrangler 
besides the Senior, 
SOCIETIES AND ACADEMIES 
LONDON 
Royal Society, December 8, 1881.—‘‘ On the Development 
of the Skull in Lepidosteus osseous,” by W. K. Parker, F.R.S. 
The materials for the present paper were kindly sent to me 
by Prof. A. Agassiz; they were for the use of Mr. Balfour 
and myself, and consisted of fifty-four small bottles of eggs and 
embryos in various stages. These very valuable materials were 
obtained from black Lake by Mr. S. W. Garman and Prof. 
Agassiz, and many of the embryos were described and figured 
by the latter in the Proceedings of the American Academy of 
Arts and Sciences, October 8, 1878. 
We have had additional materials from Prof. Burt G. 
Wilder ; Mr. Balfour has obtained from Prof. Agassiz several 
adult fishes in spirit ; and I am indebted to Prof. Flower for an 
adult in the dry state. 
Mr. Balfour’s part of the work has been done with the assist- 
ance of my son, Mr. W. N. Parker, and their joint labour will 
include the anatomy of various organs of the adult fish. 
My observations on the skull and visceral arches have been 
made on embryos and young, varying from one-third of an inch 
to 44 inches in length ; I have (artificially) divided these into six 
stages. Cartilage was being formed in the smallest examined by 
me, but in my second stage, embryos five-twelfths of an inch 
long, this tissue was quite consistent, and I succeeded in dis- 
secting out all the parts. The large notochord at this stage bends 
downwards under the swelling hind-brain, and turning up a little 
at its free end, and passing into the lower part of the fissure 
between the mid- and hind-brain, it reaches beyond the middle 
of the cranium, and just touches the infundibulum and distinct 
pituitary body. Between the trabeculae, in front, there is a 
small wedge of younger cartilage, the rudiment of the “‘inter- 
trabecula,” 
As in the Batrachia, the fore part of the palato-quadrate 
cartilage is continuous with the trabecule in front; but the 
pedicle is free behind. The free articulo-Meckelian rod is quite 
in front of the eye-balls, and is nearly as long as the hind sus- 
pensorium, or proper quadrate region ; this forward position of 
the hinge of the mandible is not temporary, as in the frog, but 
permanent. The uppermost element of the hyoid arch is an 
anvil-shaped cartilage from the first, and ossifies afterwards, as 
the hyo-mandibular and symplectic bones. As pointed out to 
me by Mr. Balfour, its dorsal end is continuous, as cartilage, 
with the auditory capsule above. The basi-hyal is not yet 
ossified, but distinct inter-, cerato-, and hypo-hyal segments are 
already marked out. Four larger and one small rod of cartilage 
are seen on each side, articulating with a median band ; these 
are the branchial arches, which chondrify before they undergo 
segmentation. In this stage there are no osseous laminz as yet 
formed, ; 
Here, in this stage, in connection with a large pre-nasal suc- 
torial disk, we have three important generalised characters, 
namely, the continuity of the distal end of the mandibular pier 
and of the proximal end of the hyoid pier with the skull, and 
the forward position of the hinge of the jaw coupled with the 
horizontal direction of the suspensorium. The hyoid arch has 
its segments formed much earlier than in the Teleostei, and the 
‘«pharyngo-branchials” are not independent cartilages, as in 
the Skate. 
The third stage—embryos two-thirds of an inch long—show a 
considerable advance in the development of the skull; the 
cartilage, genera)ly, is more solid and more extensive, and new 
tracts have appeared. The apex of the notochord is now in the 
middle of the basis cranii, for the pro-chordal tracts have grown 
faster than the para-chordals. The trabeculze swell out where 
they are confluent, and then are narrower in front again. At 
their fore end each band passes insensibly into the corresponding 
palato-quadrate bar outside, whilst inside they are separated by 
a large pyriform wedge of cartilage, the intertrabecula. The 
thick, rounded, free fore end of this median cartilage is the rudi- 
ment of the great ‘‘nasal rostrum,” and the rounded fore ends 
of the trabeculz are the rudiments of their “ cornua.”’ 
There is only a floor in the occipital region, but the wall-plate 
of the chondrocranium has begun as a styloid cartilage running 
forward from the fore end of each auditory capsule into the 
superorbital region. The palato-pterygoid bar—continuous in 
front with the trabeculae—is now longer than the proximal part 
of the suspensorium, the spatulate quadrate region whose dorsal 
end is the free pedicle. ‘The wide proximal part of each 
trabecula is now already forming an oblong facet, the basi- 
pterygoid, for articulation with the facet of the pedicle, 
In this stage the skull is a curious compromise between that 
of a salmon at the same stage and that of a tadpole just be- 
ginning its transformation. The hind-skull is quite like that of 
a young salmon, the fore-skull, with its non-segmented palato- 
quadrate, and its forwardly placed quadrate condyles and hori- 
zontal suspensorium, is very much like what is seen in the 
suctorial skull of the Anurous larva. <A splint bone, the para- 
sphenoid, as in the tadpole, has now made its appearance. 
The largest embryos reared by Messrs. Agassiz and Gorman, 
which are about one inch in length, form my fourth stage ; these 
are rapidly acquiring the character of the adult, 
This is the stage in which the chondrocranium of this Holo- 
stean type corresponds most closely with that of the Chondro- 
stean sturgeon, whose adult skull is similar to that of garpike 
just as the Jatter begins to show its own special characters. This 
important difference is already evident, namely, that whilst in 
Acipenser the olfactory capsules remain in the antordital position, 
those of ZLepidosteus are already carried forwards by the growing 
intertrabecula, and are even now in front of the relatively huge 
cornua trabeculz. Thus these regions are now well grown in 
front of the ethmoidal territory, which, instead of being, as in 
the last stage, in the front margin of the skull, is now fairly in 
its middle, and this change has taken place whilst the embryo 
has only become one-half larger—from two-thirds of an inch to 
an inch in length, It is the hypertrophy of cartilage in the 
three trabecular tracts that makes the rostrum of the sturgeon so 
massive, even whilst only a few inches in length, and this state 
of things exists temporarily in the garpike. 
Above, the sphenotic, epiotic, and opisthotic projections of 
the auditory capsule are more evident, but are not ossified. 
Some slight bony deposit has appeared in the pro-otic regions. 
The ‘‘cephalostyle”’ is the first evdo-cranial bone, and the para- 
[ Fed. 2, 1882 
