248 SUMMARY OF CURRENT RESEARCHES RELATING TO 



heart into two halves, which are in contact with the rectum. In A. 

 nose and .1. angulaia the heart is double and distant from the intestine 

 In all Arcidae there is an abdominal sensory organ on each side of the 

 anus, which is sensitive to movements and impurities in the water. 



In Area there are always two separate pericardial cavities. There 

 may he one ventricle with lateral lobes, or two ventricles. There may 

 be a sphincter on each side between the ventricle and the auricle, or 

 there may be anriculo-ventricular valves. The auricles consist of a 

 larger lateral and a smaller median portion. The median portions 

 communicate in A. platei and A. scapha. There is an aorta both 

 anteriorly and posteriorly. A series of different grades occurs from 

 single pericardium and ventricle to double pericardium and ventricle. 

 In A . scapha the heart is remarkable in being supra-rectal. The author 

 calls attention to the fact that Area {Barbatia) barbata and Area 

 {Barbatia) platei are very closely alike as regards shells, and yet show 

 very marked anatomical differences. 



Estimating Age of Oysters.*— Anne L. Massy finds that reliance 

 cannot be placed on the method of estimating the age of oysters by the 

 groups of rings on the deep valve. She has dealt with 638 oysters of 

 known age (from Ardfry Station in Galway Bay), and finds that an 

 oyster of eighteen months or two summers has at least two rings, but 

 may have as many as five. One of three summers has at least two 

 rings, and may have six. A four-year-old oyster may have only three 

 rings, or may possess seven or eight. 



Arthropoda. 

 a - Insecta. 



Evolution of Colour Pattern in Lithocolletis.f— Annette Frances 

 Brown has studied the development of the colour in the pupal wings in 

 this genus of Tineid moths. The primitive colour pattern is a series of 

 seven uniformly coloured pale yellow transverse bands, separated from 

 one another by unpigmented areas. The disposal of these bands is 

 dependent upon the course of the longitudinal nervures, since the points 

 of origin or the tips of the veins mark the positions of the unpigmented 

 fasciae between the bands. 



From this primitive colour pattern the various types of the genus 

 have been derived. Evolution has taken place in definite directions 

 under the action of three general processes, which were found to be 

 sufficient to explain the origin of the different colour patterns. 1. The 

 middle portion of a band may be produced distally until it comes in 

 contact with the band beyond it. 2. The extremities of a band may be 

 broadened by being produced proximally. 3. The extremities of a band 

 may be narrowed by the retraction of pigment from their outer edges. 



During pupal development these phylogenetic changes are repeated 



* Sci. Invest. Fisheries Ireland, 1913, No. 2 (published 1914) pp. 1-12 (11 pis.). 

 t Journ. Acad. Nat. Sci. Philadelphia, xvi. (1914) pp. 105-65 (2 pis. and 24 figs.). 



