446 REPORT—1890. 
doubt that many points of interest, both in the anatomy and in the 
histology of the Lamellibranchiata, will also be observed. 
II. Report on the Occupation of the Table. By Mr. W. G. Ripewoop. 
On the Air-bladder of Clupeoid Fishes. 
The air-bladder of the herring communicates by a ductus pnewmaticus 
with a backward prolongation of the stomach; it also communicates 
directly with the exterior, in the region of the anus, by a smali papilla, 
which opens just within the aperture of the short urinogenital chamber 
or sinus, 
The anterior end of the air-bladder is continued, after two bifur- 
cations, into four sacs, each of which lies within its own tightly-fitting 
bony capsule. The anterior pair of sacs are in intimate contact with a 
pair of cecal processes of the membranous vestibule of the ear, while 
the posterior pair are situated within the loop of the horizontal semi- 
circular canal. 
Although Weber! gave an excellent account of this anterior termi- 
nation of the air-bladder in 1820, it would appear that of the whole of 
the clupeoid fishes only the common herring (C. harengus) has been 
minutely studied with reference to this arrangement, and the object of 
the projected investigation is to determine how far these complicated 
relations obtain in the closely allied species and genera. 
In view of the great complexity of these relations it would be reason- 
able to expect a certain amount of variation in the allied forms, while, if 
the investigation be attended with the opposite result, it will tend to 
show that the system of classification of these fishes now adopted by 
ichthyologists is a true and a natural one. 
III. Report on the Occupation of the Table. By Mr. E. A. Mincuin. 
T am investigating the structure and life-histories of the various 
species of Gregarinids parasitic on marine animals, especially those 
inhabiting Holothuria. I have already obtained and studied three species 
which I believe to be as yet undescribed, and which are parasitic on 
Nebalia, Gammarus locusta, and Phallusia mammillata respectively. I 
have also found several stages of the Gregarine inhabiting the body- 
cavity of Holothuria, described very inadequately by Schneider in 1858 
in the ‘ Archiv f. Anat. u. Physiol.,’ and have obtained some good results 
by studying this form by means of sections. I have also, incidentally, 
made a number of observations on the corpuscles in the body-cavities of 
Holothuria and Echinus. 
I hope to be able to work out the minute structure of the Gregarine 
nucleus and its behaviour during conjugation and encystment, using 
sections and other methods for the purposes of this investigation. 
The experience gained by the Committee during the past year has 
convinced them that the grant made by the Association has been of 
material service in assis ing well-qualified persons who were anxious to 
work at the Laboratory at Plymouth. The investigations which are now 
1 De Aure et Auditu Hominis et Animalium. 
