ZOOLOGY OF SEAHAM HARBOUR. 31 U 



XXIII. — Contributions to the Zoology of Seaham Harbour. By 

 George Hodge. (PI. XVI., fig. 1-6.) 



1. On a New Marine Mite ( Pachygnathus Seahami). 



On the 4th of February I brought some tufts of Corallina offici- 

 nalis from the rocks, and whilst carefully examining them with 

 a hand lens, a small insect was noticed running along one of the 

 stems; it was immediately placed in an Animalculse cage, and 

 examined by the microscope, when it was seen to present a 

 strong family likeness to the Acari tribe. Mr. Gosse's excellent 

 '• Manual of Marine Zoology " was consulted, but, from his 

 figures and descriptions, I could not name my capture, certain 

 differences too striking to be passed over being apparent. Camera 

 Lucida sketches were made of the insect, and of those parts most 

 likely to afford a clue whereby to decide its character. A tracing 

 from these, and a couple of the Acari (others having been found) 

 were sent to Mr. Gosse, who very kindly gave it his attention, 

 and informed me " that it agreed with his Pachygnathus notops^ 

 except in the form of the claws, which is very peculiar, and 

 must, I presume, constitute it a new species." Mr. Gosse not 

 being able (from want of time) to forward a full description and 

 figures to the '' Annals," thought it better for me to describe it, 

 as he knew of no other difference between my species and his. 



I therefore beg to submit to the Tyneside Club a sketch of the 

 insect, also of the mandibles and one of the claws, drawn under a 

 high magnifying power. It will be observed that the hooks at 

 the extremity of the claws are very finely pectinated, a very 

 careful adjustment being required to show these pectinations. 



These Acari are very common on the stems of Corallina and 

 other littoral Alg^, and it seems surprising that they should not 

 have been noticed before ; probably their minute size may ac- 

 count for their having been overlooked. 



From its general resemblance to Pachygnathus notops, it may 

 be considered to belong to this genus ; and such being the case, I 

 would propose, as a distinguishing name, that of the locality 

 where it was first found. I have therefore named it Pachygnathus 

 Seahami. 



