NOTES OX A DEEP-SEA ECHIUEOID. 145 



mality seems hardly to imply a degeneration, as it causes no 

 essential change in the structure of the whole hook-apparatus, 

 except in the number of hooks. But it seems to me very 

 probable that even this kind of abnormality actually indicates 

 a certain phase antecedent to the total degeneration of the 

 hooks as known in Bonellia misakiensis^ or in the genus 

 Haraingia, if we take into consideration the present case in 

 which the abnormality in number is coupled with the entire 

 absence of the muscular apparatus. If considered from the 

 point of view of the ventral hooks only, the two species, which 

 are similarly characterised, may be looked upon as if they 

 were an intermediate form between Proto bonellia and 

 Hamingia, both of which have the ordinary proboscis. But 

 such a view as the above cannot be maintained if we take 

 into consideration the anomalous anal glands possessed by 

 the two species, because sucli a multiplied condition of the 

 organs could not be regarded as an intermediate characteristic. 

 Besides, we see in the embryology of the group Echiuroids 

 that the anal glands arise at first as two paired in-growths of 

 the ectoderm near the larval anus. 



The facts and considerations stated above point to the 

 conclusion that the present species and that which I described 

 formerly as Hamingia ijimai are to be classed as a genus 

 distinct from any already existing in the Echiuroids. I pro- 

 pose to call the nesv genus Acanthohamin gia and the two 

 allied species respectively as Ac. ijimai and Ac. shiplei, 

 the new species being named in honour of Mr. A. E. Shipley, 

 F.E.S. 



The new genus may be diagnosed as follows : 



ACANTHOHAMINGIA. 



A sexually dimorphic Echiuroid. 



Female. — The shape of the proboscis is much like that of 

 Thalassema; the skin is thin and delicate in texture, with 



* Ikeda, I., " The Gepliyrea of Japan,'" ' Jouni. Coll. Sci. Imp. iriiiv. 

 Tokyo, Japan,' vol. xx, ai-t. 4, 1904. 



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