ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 337 



primitive form or Archiptjcnogonum might be defined as a Pycnogonid 

 of large size, with strong mandibles of three joints, and armed with a 

 terminal claw, with long palpi of ten joints, with ovigerous legs of 

 ten joints, the last four of which are spinous. The thoracic limbs 

 have eight joints, and end in a claw, with two accessory claws. The 

 descendants of this form are either delicate and have their limbs 

 articulated at a considerable distance from one another, or they are 

 robust and their limbs are set close to one another. Four natural 

 families may be distinguished — Nymphonidae, Ascorhynchidse, 

 Colossendeidse, and Phoxichilidae — by the aid of the differences 

 exhibited in the structure of the appendages. 



Spiders' Webs.* — Mr. E. J. Lecky, referring to the discussion at 

 the January meeting of the Society (ante, pp. 142-3), writes : — " The 

 geometric spider never spins a glutinous web ; the entire net is first 

 made, beginning with the long stays (those alone suitable for optical 

 purposes), then those at the circumference, next the radial threads, 

 finishing the net with the spiral ' ratlins ' (to use a nautical expres- 

 sion). When these are complete, the spinner begins at the ' ratlin ' 

 next to the exterior threads, and bedews them at regular intervals with 

 the glutinous fluid, walking round and round until all is complete. 

 This fluid spreads, in time, over the ' ratlins,' and so the thread 

 appears as if spun in a glutinous state at the commencement." 



5. Crustacea. 



Limulus a Crustacean. t — Di'- A. S. Packard, jun., who has also 

 devoted much attention to this form, replies to Professor Lankester's 

 paper on the Arachnid nature of Limulus,'^ maintaining that his 

 conclusions are untenable. The criticism is not susceptible of 

 abstract beyond the statement that Dr. Packard considers Professor 

 Lankester has not correctly described the differences between the 

 brain and the thoracic ganglionic mass of the scorpion and Limulus, 

 that in the morphology of the brain the latter much more nearly 

 approaches Ajms and other Phyllopods than Arachnids, that four of 

 the six segments described by Professor Lankester between the 

 sixth abdominal segment and the spine are imaginary, as is also his 

 view that the scattered simple eyes of the scorpion are really com- 

 pound eyes, and some attempts to homologize parts of the scorpion 

 with Limulus. 



Segmental Organs in Isopoda.f — Lereboulet in 1850 concluded 

 that the Cloportides (Wood-lice) are allied to the Spiders, by the 

 existence of special glands, secreting a silky substance ; but M. Huet 

 considers that the facts he has observed would equally enable them 

 to be referred to the Annelida or Myriapoda. 



There are glandular organs not only in the caudal region of these 

 animals, but in each of the seven segments of the body. They are 

 absent from the head. They open in the superior portion of the 



* Engl. Mech., xxxiv. (1S82) p. 496. 



t Ann. and Mag. Nat. Hist., ix. (1882) pp. 3G9-74. 



X Cumptcs Rcudus, xciv. (1882) pp. 810-11. 



