Mr. A. Tulk on the Anatomy of Phalangium Opilio. 249 



to protect the delicate coats of the intestine from laceration, by 

 the sharp and often spiny nature of their contents. 



Of the two pairs of vessels described by Treviranus and men- 

 tioned above as biliary tubes (Gallgefasse), the superior (PI. TV. 

 fig. 17. sv, sv), after forming a loop upon the posterior rows of 

 small caeca, winds round the intestine from the dorsal to its ven- 

 tral aspect, where it crosses part of the ovarium in the female, and 

 is in relation with the origins of the tracheal trunks, and returns 

 into itself to form a single tube, which passes directly forwards, 

 and is lost among the muscles of the manducatory apparatus. 

 The second pair (PI. IV. fig. 18. sv^ sv') are situated more to the 

 sides of the alimentary canal, but I have been unable to trace 

 their course. Treviranus states that it is shorter than the pre- 

 ceding one, and ends between the cescal pouches. It is, however, 

 probably also continued onwards to the cibarial organs, and the 

 two pairs together may, perhaps, exercise some salivary function 

 in relation to those complex parts. 



The structure designated by Treviranus as the fatty mass (/) 

 consists of a series of longitudinal and parallel intestiniform bodies, 

 formed by membranous tubes, containing granular matter in 

 their interior, and which lie upon the under surface of the sto- 

 mach. They may fulfil the function of a liver. 



Organs of Circulation. — These in Phalangium are as simple as 

 the other structures are complicated. They consist of a heart 

 divided into three chambers, lying in a groove upon the upper 

 surface of the alimentary canal. The posterior division (PL IV. 

 fig. 17. p) is situated, pyriform in shape, between the anterior ex- 

 tremities of the two large superior cseca, its broad end forwards, 

 being received into a corresponding expanded portion of the 

 groove. The middle chamber (H), about the same size as the 

 two terminal, is contracted in the middle like an hour-glass, and 

 placed between the two posterior rows of small cseca, being in 

 relation, upon either side, with the longitudinal portion of the 

 loop of upper salivary vessels. The anterior division (a"), of the 

 same shape as the posterior, lies in a depression between the two 

 anterior rows of cseca, and is prolonged downwards obliquely as 

 a minute vessel, which, curving again upon itself, runs horizon- 

 tally forwards. The structure of the heart is composed of a se- 

 ries of transverse, curved and muscular bands, leaving between 

 them light and membranous intervals. It is plentifully supplied 

 with nerves, which take a longitudinal course over it. 



Generative Organs. — Were the anatomist familiar only with 

 the anomalous conditions of the generative system in the Pulmo- 

 nary Arachnida, with the singular transference of the means of 

 fecundation to the extremities of the palpi in the male spider, and 

 the termination of the internal organs, in both sexes, by a simple 

 Ann. ^ Mag. N. Hist. Vol. xii. S 



