iSlf^.] UNUSUAL ARRANGEMENT, &c. 401 



Length of the female nine twentieths of an inch, male 

 much smaller. 



Varies very much in its colours, is of a plain brown- 

 ish horn colour, rarely ferruginous, very ofttn marked 

 with two large patches of whitish or rosaceous, one of 

 which is placed on the anterior disk and the other on the 

 base of the tail, connected by a whitish dorsal line; some- 

 times we have a dorsal line only, extending from the 

 head to the tail. 1 found these animals very numerous 

 ©n the beach of St. Catherine's island, Georgia, conceal- 

 ing themselves under the raised bark, and in the deserted 

 holes of the Teredo, &c., of such dead trees as are peri- 

 odically immersed. They always swim on their backs. 



(To be continued.) 



A case of unusual arrangement in the ascending Cava 

 and in the external Jugular Feins of the Human Sub^ 

 ject. By William E, Horner^ M, D. Read August 

 18, 1818. 



While prosecuting a course of dissections in the year 

 1813, the subject of the present paper accidentally fell in- 

 to my hands. After injecting its blood vessels with the 

 view of making a dried preparation, I was much surprized 

 to find, in the course of the dissection, that an important 

 part of its vascular system deviated in a very singular man* 

 ner from what is commonly observed. Having submitted 

 the preparation to the examination of Dr. Wistar, late pro- 

 fessor of anatomy, the interest he took in it induced me to 

 present it to him, and it is now an article in the Anatom- 



