Modified, so that the study of their relations becomes a matter Maxillary palpus, x.

Max- o f some difficulty.

In the spiders, if we regard all four of the walking feet as thoracic, there are but two pairs of appendages which can be regarded as belonging to the head, the cheliceiae, or mandibles, and the palpi, or pedipalpi.

The head also bears the eyes.

In the spiders and most myriapods only simple eyes or ocelli are found ; but in most hexapods we have a pair of compound eyes, and usually, except in most beetles, two or three ocelli in addition are present.